National Institute for Fusion Science
Special Review Meetingby Advisors and Foreign Researchers
in FY 2008
Review Report

March, 2009

Contents

1.

Agenda for the Meeting ･････････････････････････････････････････････ 1

2.

Reviews on NIFS Research Activities ････････････････････････････････ 3

3.

Brief Summary ････････････････････････････････････････････････････ 35[Attachments](a) Translation into Japanese(b)Attached Documents

1.

Agenda for the Meeting

NIFS Special Review Meeting by Advisors and Foreign Researchers in FY 2008
December 13, 2008 (Sat.)
Special Conference Room 3F, HIDA Earth Wisdom Center, Takayama, Gifu, Japan

Reviewers:● Advisors
Prof. Hiroshi Takuma

Advisor (Emeritus Professor, the University of Electro-Communications)

Prof. Kyoji Nishikawa

Advisor (Emeritus Professor, Hiroshima University)

Prof. Michael Tendler

Advisor (Professor, Royal Institute of Technology, Sweden)

Prof. Satoshi Itoh

Advisor (Emeritus Professor, Kyushu University)● Foreign Researchers
Dr. Carlos Alejaldre

Deputy Director-General for Safety and Security, ITER, France

Dr. Gyung-Su Lee

President, National Fusion Research Institute, Republic of Korea

Prof. James W. Van Dam

Director, Institute for Fusion Studies in the University of Texas at Austin,
USA

Prof. Robert Wolf

Professor, Max-Planck-Institute for Plasma Physics, Germany

Prof. Thomas Klinger

Professor, Scientific Director of Max-Planck-Institute for Plasma Physics,
Germany

NIFS members:
Prof. Osamu Motojima, Prof. Shigeru Sudo, Prof. Akio Komori, Prof. Hiroshi Yamada,Prof. Shinsaku Imagawa, Prof. Noriyoshi Nakajima, Prof. Shoichi Okamura,
Prof. Motoyasu Sato, Prof. Akio Sagara, Assoc. Prof. Satoru Sakakibara,
Assoc. Prof. Ryuichi Sakamoto, Assoc. Prof. Masayuki Yokoyama,
Assoc. Prof. Tomohiko Watanabe, Assoc. Prof. Takuya Nagasaka, Mr. Yasuo Kainai

1Program:
8:30
Opening
8:30 Opening Address (5 min)Director-General, Osamu Motojima
8:35 8:55 -12:50 -

17:05 17:45 17:50

Introduction of NIFS Activities (20 min)
Deputy Director-General, Shigeru Sudo
Current status and research subjects, future plans of NIFS (160 min)
[40 min / item (Report 25 min + Q&A 15 min)]
8:55 - 9:35
Large Helical Device (LHD) Project
Executive Director, Akio Komori
9:35 - 10:15 Simulation Science Project
Director, Noriyoshi Nakajima---- Coffee Break (15 min) ---10:30 - 11:10 Coordination Research
Director, Motoyasu Sato
11:10 - 11:50 Fusion Engineering Research
Director, Akio Sagara---- Lunch Break (60 min) ---Recent results and topics (240 min)
[60 min / item (Report 40 min + Q&A 20 min)]12:50 - 13:50 High Beta and Related 3-D MHD Characteristics
Assoc. Prof. Satoru Sakakibara
13:50 - 14:50 High Density Operation and Its Prospect for Helical Reactor
Assoc. Prof. Ryuichi Sakamoto---- Coffee Break (15 min) ---15:05 - 16:05 Turbulent Transport and Zonal Flows
Assoc. Prof. Tomohiko Watanabe
16:05 - 17:05 Development of long-life liquid blanket
Assoc. Prof. Takuya Nagasaka
General comments from reviewers (40 min)Closing Address (5 min)Director-General, Osamu Motojima
Closing2

2.

Reviews on NIFS Research Activities

Reviewer: A
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
The achievements of LHD Project since its start-up in 1998 are very impressive and cover all the main
issues needed to be solved for the successful development of fusion energy, giving tremendous hope forhelical systems as fusion energy producers, as most if not all the parameters needed for efficient fusion
production in terms of density or pressure have been achieved. The challenge now is to do themsimultaneously.
Furthermore the more extreme operational regimes investigated show no sign of having reached any
fundamental physical limit other than the technical limitation associated to heating sources orparticle/energy exhaust and in both cases, upgrades are foreseen.
In my opinion, LHD has proven for the first time in the History of Fusion Research that helical systems
are serious candidates for future generations of fusion power, having properties quite similar toadvanced Tokamaks but without the difficulties associated to a strong toroidal current: instabilities,
disruptions, density limits…..
Technically, to prove the capability of stable plasma production for over one hour is an achievementthat could be extended to more demanding regimes.

b) Specific Researches (on topics)
The development of the disruption-free, high density regime is in my opinion one of the more hopefuls
regimes developed by the fusion community in the last years.
The extension of <ß> to reactor relevant values of 5% is again a breakthrough that should behighlighted, particularly because it looks like the actual limit of the configuration has not been reachedand the absence of hard limits is very encouraging.

c) Future Plan
Given the results obtained, the plans to upgrade the heating capability of the machine, the introductionof a closed helical divertor and working with deuterium are absolute needs and I would recommend that
all efforts are made to find the needed resources to take the machine to its physical limits.
(2) Simulation Science Projecta) General View and Achievements
A very ambitious project was presented on plasma simulation that covered specific LHD confinement
simulation as well as laser fusion simulation with very encouraging results already. The fact that thisgroup works closely with the experiments is in my opinion something that should be supported. It was3

very good to see that young generations are participated actively in this field.

b) Specific Researches (on topics)
To include in the simulation data coming from other machines with quite detailed diagnostics for radial
electric fields like TJ-II could be a good addition to the very excellent work presented.
The work on materials is particularly important for the future of fusion machines.
I would recommend that comparison with Tokamaks is taken into account.

c) F uture Plan
The plan presented is very ambitious but realistic at the same time. Adequate computing resources
should be obtained at the highest level for this task to be successful.
(3) Coordination Researcha) General View and Achievements
I would like to praise the effort done in this field. It is very normal in other large experiments to bedisconnected from other communities, but it was a pleasure to see the on going interactions withindustry, other scientific institutions and the fusion laser community as well as outreaching programs.
I would strongly encourage to emphasize the work on “tritium for Fusion”, since as we approach theoperation of ITER, more and more issues have to be resolved and through this collaborative effort agreat contribution could be expected. This is a key-issue to be solved for the successful implementationof fusion energy.

The effort made on “Kids Fusion Science Museum” is to be highly praised.

b) F uture Plan
Special care has been taken to present future plans taking into account the planning of the ITER project
and that is in my opinion the key to success since ITER will clearly have a strong influence in all fusion
world programs.
I would recommend a closed interaction with JAEA
(4) Fusion Engineering Researcha) General View and Achievements
The subjects of the research presented were very well chosen and the results obtained world-relevant.
Many international collaborations are maintained, giving good confidence in the impact of the research.
To include objective indicators like publications is also very useful for reviewers.

4b) Specific Researches (on topics)
Long life liquid Flibe and Li blanket studies were impressive. The main difficulty will be thepossibilities to test in real environment these designs as the possibilities to do it in ITER are limited.
Neutronics studies are very much needed and welcome in view of the approaching ITER operation.

c) F uture Plan
For its importance, enough resources should be found for the future plan presented.
2. Others
I would like to take this opportunity to congratulate the whole NIFS for the achievements of the lastyears. They covered not only experimental results in LHD that are world record relevant but for all theaccompanying program that surrounds LHD in science, collaborations with so many institutions inJapan and worldwide, technology program as well as a very important, even if modest, public relations
program.
It is very encouraging to see a new generation of young scientists and engineers already producing
world-class results and I would recommend that for the next review, special thought be given as to how
to maintain such high standards and world leadership for the long term.
The whole team should be proud of the achievements obtained under the leadership of Prof. Motojima
and I would like formally to give him my congratulations with the request that it be given to the whole
team.

5

Reviewer: B
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
The fusion energy research has been mainly studied by the tokamak type devices.
Even if TRIAM-1M has already demonstrated steady-sｔate operation using LHCD. However, thetokamak type is difficult to achieve the high efficient continuous operation. On this point of view thehelical devices are extremely favorable.
But before LHD experiments, the research for the helicalfusion “reactor” has almost not studied. For last six years the LHD experimental research has been
carried out energetically, and the high temperature and high density plasmas are established.
Especially the achievement of the highβof 5% seems to be amazing result.
The results which are higher than initial expected parameter are should be evaluated as the valuable
results.

b) Specific Researches (on topics)
1. High ion temperature : 5.2 keV at n e = 1.6x10 19 m-3
2. Maximum β=5.1%,
3. Maximum density :4.5% for the steady state (>100 τ e )1.2 x 1021 m-3

4. Prove of IBD
Furthermore many interesting results are shown.

c) F uture Plan
The power up of the heating, the closed helical diverter and D-D experiment are prepared. Then thehigher beautiful results should be expected. The setting of the helical diverter is well considered not
to effect on the experimental schedule.
The design of the helical reactor is seemed to proceed referring of the experimental results from LHD.
Reasonable design should be expected.
(2) Simulation Science Projecta) General View and Achievements
It is appreciated that the simulation study has proceeded energetically.
In the high temperature plasma miscellaneous phenomena coexist and interact each. So even if thesimulated result resembles the experimental result, its phenomena may be not same as one in accurate
plasma. We should keep mind on this point.
The simulation group and the diagnostic group should contact sharply each other.

6b) Specific Researches (on topics)c) F uture Plan
The simulation group is recommended to put emphases on the simulation of the helical reactor.
(3) Coordination Researcha) General View and Achievements
The many jobs are explained, but it is difficult to understand the final object of each jobs.
shown what “Boomerang” effect is obtained. So it is difficult to evaluate at present time.

It is notb) F uture Plan
It should be necessary to select the important tasks, for example, a helical diverter, prepare of D-Dexperiments.
The final objects should be also shown.
(4) Fusion Engineering Researcha) General View and Achievements
Blanket, neutron, magnet et cetera are explained, but the parameters of the expected reactor (size,
magnetic strength, dimensions of plasma) are not shown. If the scale of a reactor which must be
developed is shown, the attained grade is easier to understand.

b) Specific Researches (on topics)
I am strongly interested in the developed results of superconductors.

The results are evaluated high.

c) F uture Plan
The plan of the helical reactor is expected. The comparison between helical and tokamak reactors
should be carried out with considering strong and weak points. The scales of helical and tokamak
reactors should be also shown.
Considering the energy problems, the scale and budget are not so large problem but the realization ismost important.
2. Others
During these several years the organization has been improved and a lot of extreme results arereported. Especially many excellent results of LHD experiments are should be evaluated extremely
high.
I would like to say congratulation to Prof. Motojima, Director-General, and staff of NIFS.

7

Reviewer: C
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
Based on the pure academic debate between plasma nuclear fusion researchers in Japan, the Large
Helical Device project was adopted in 1986 as the next-generation large-scale research plan, which
university officials should work on with all their strength. Upon the adoption of the project, while
keeping in mind that the external conductor type helical magnetic field confinement system has thecapacity of a steady-state operation with lower re-circulating power and the capacity of a long-timesustainment of high-temperature high-beta plasmas, it was desired that LHD, for the time being, would
contribute to a comprehensive understanding of plasma physics by the torus magnetic field
confinement system including the internal current type tokamak devices. As specific research plans,following subjects were addressed: 1) the optimization of the high nτT plasma confinement by various
magnetic configurations; 2) elucidations of a) physics like the pressure-driven instability in thehigh-beta region as well as b) its impact on the confinement; 3) the control of impurities due to along-time operation and the provision of basic resources concerning issues like a fuel supply anddischarge; 4) research in the high-energy particle confinement characteristics under the helical ripple
magnetic field; 5) nuclear reaction simulation research; and so on.
It is highly commendable that the LHD project, following the above research goals, has been
consistently carried out for the past 10 years ever since its first shot in March 1998, that it has produced
the results almost as they were primarily expected, and that it has made a unique and valuable
contribution to the global core plasma magnetic field confinement research. Especially, it has largely
contributed to the comprehensive understanding of a torus magnetic field confinement system that has aprospect over the nuclear fusion reactor core such as the actualization of the long-time sustainment of
the high-beta plasmas to provide the important basic resources in terms of their MHD characteristics,
transport, or peripheral control and also the discovery of ITB that maintains the central peakhigh-density by means of the pellet injection.

b) Specific Researches (on topics)・ Optimizing the confinement
By changing the position of magnetic axes and the aspect ratio, the confinement of high-beta plasmas
was optimized in terms of the MHD characteristics, heating efficiency, and transport. The maximum<β>=5.1% was achieved. Also, the steady-state operation that is 85 times as long as the energy
confinement time was actualized at <β>=4.8%. Furthermore, while methodically examining the impact
on MHD equilibrium, stability, and transport due to the pressure-driven instability and the peripheral
magnetic surface collapse, heating by the vertical neutral beam injection was actualized to study theirconfinement characteristics. Reviewed from the standpoint of torus magnetic field confinement plasma
physics and also from the point of views that overlooks a reactor, these results made highly excellent
contributions.
・ Internal Diffusion Barrier (IDB)
While generation and maintenance of the central peak high-density, high-pressure configuration werealready found out in the conventional local island diverter configuration at the time of a consecutive
pellet injection to the central part, it was newly discovered that they could also be actualized in theordinary helical diverter configuration by means of an outward shift of magnetic axes and so on; thus,
8their operation region (magnetic axis / β) was identified. I believe that it is such an important progressfrom the standpoint that surveys the reactor core plasma generation and sustainment in the helicalsystem. According to the experiment result, the electron temperature gradient stays gentle even where
the electron density gradient is steep. It is further expected that from now on, a detail study should be
carried out in cooperation with the Theory and Simulation groups to elucidate the physical mechanismof diffusion coefficients considering the IDB formation as well as to identify and control instabilities
like CDC.
・ Edge Plasma Control
Control of a peripheral magnetic surface disorder as a result of the beta value increase is a challengethat cannot be ignored when one attempts to bring the helical type plasma sustainment into a
steady-state operation. The fact that the confinement deterioration was not observed in the region <β>– 4.8% is an achievement to be noted.
Also, varieties of researches are carried out such as the generation of impurity halls under the high ion
temperature, the impurity shielding by means of a collision friction at a high density, various analyses
concerning the effect of the ergodic layer, designs of the closed helical diverter configuration, and soon. Further progress will be much expected to those respectively as research that may provide moreinsights on the peripheral control of particle / heat flux.

c) F uture Plan
The most desirable future plan is the start of the deuterium experiment. Well, it can be understood thatit involves a quite difficult issue to obtain the public permission; however, taking into consideration thatthe original plan has been carried out up until now, I cannot stop hoping that the research in theconfinement characteristics by using deuterium, especially research in the isotope effect to theconfinement scaling law of the ions and impurity particles shall be started. Then, I anticipate further
that, those researches would eventually develop into a nuclear reaction simulation research by the ICRF
minority heating due to the mixing of a small amount of He3.
Yet, I say that any major reconstructions or a new construction of another large helical device is still too
early to carry out at this point. For the time being, it will be best to aim at a further progress in researchby utilizing the present LHD (necessary upgrades or reconstruction like the heating power
reinforcement and the diverter configuration remodeling should be taken care of). Then, the next term
research plan should be carefully thought over, studying the ITER and ICF related achievements, fromthe standpoint of the nuclear fusion research in general.
(2) Simulation Science Projecta) General View and Achievements
First of all, I would like to highly commend the simulation research group for the fact that it hasdeveloped into a big research group. Then, I want to congratulate the group on the achievement that thegroup succeeded in carrying out 3 projects simultaneously: 1) LHD and Magnetic Confinement
Simulation Project; 2) Laser Fusion Simulation Project; and 3) Plasma Complexity Simulation Project.
Among those three, 1) LHD and Magnetic Confinement Simulation Project is the central project.
In this project, 3 sub groups – the two-fluid model research group, the kinetic model research group in
the core plasma, the kinetic model research group in the core plasma, and the peripheral plasma
research group – have made sure and steady research achievements by developing the two-fluid model,
the gyro kinetic model, and the boundary modeling, respectively. Furthermore, it seems reasonable that
NIFS attempts to develop a multi-hierarchy simulation model by integrating the research results of9

these 3 sub groups and, thus, to promote the Numerical Test Reactor Project. At the same time, it will
be much expected that this research project will play a leading role in the simulation research related tothe multi-hierarchy phenomena in various fields.

b) Specific Researches (on topics)
I think that the achievements made in the research in the ITG turbulence and zonal flows in the helicalsystem by using the gyro kinetic Vlasov model will deserve a special attention. Many researches on the
ITG turbulence and its stabilization by the zonal flow have already been carried out in axisymmetrictokamak system. In the non-axisymmetric helical system, too, the zonal flow and its turbulence
suppression effect are likewise confirmed experimentally with the NIFS compact helical device (CHS).
Yet, I suppose that it is the first time when the detail analysis by means of simulation research in thehelical system was performed. The analysis was performed while taking into consideration the radial
electric field effect due to non-axisymmetricity, and it revealed that the turbulence diffusion
suppression due to zonal flows would work strongly in the magnetic field configuration that minimizes
the neo-classical ripple diffusion and that the turbulence diffusion be thus suppressed. Some parts arestill left uncertain about how the radial electric field was adopted; yet, analyses that self-consistently
adopt the electric fields generated due to the ambipolarity of the particle diffusion flux will be further
expected.

c) F uture Plan
Modeling and the simulation numerical method are the keys in the simulation research. These are notlimited within specific subjects (helical plasmas), but they can also be applied to many different
complexity analyses. In fact, researches on self-organization in the open system, that were major
subject in the previous Theory and Computer Simulation Center were developed into the application to
many other fields of research.
One can conclude that the researchers have developed a new paradigm of the method to research thesystems with complexity in nature.
The comprehensive research in the multi-hierarchy phenomena has become a subject that cannot be
avoided in such areas like research in the global scale weather phenomena as well as the atmosphereand ocean current, research in the earth inner structure and diastrophism, or in the areas of bioscienceand space science.
I would truly hope that through active collaborative researches with related research organizations
including other NINS institutes, the Department of Simulation Science should play a central role to leadthe way for new simulation research that includes various fields of researches addressed above.
(3) Coordination Researcha) General View and Achievements
It should be specifically noted that the Coordination Research Center has been carrying out various
activities like the international collaboration, ITER related research collaboration, laser related researchcollaboration, atomic/ molecular/edge plasma data collection and analysis, industrial collaboration, andthe NIFS Science Museum for Kids with only a limited number of personnel.
From the aspect of nuclear fusion science, activities were more or less focused on spin-off related
actions in the past; therefore, it is quite desirable that they are now being shifted toward actions aiming
at a nuclear fusion reactor.

10b) F uture Plan
It will be much expected that more emphasis will be placed upon collaborative researches in tokamaks(ITER, torus tokamak), which is believed to actualize a nuclear fusion reactor in the shortest span at
this point along with a helical series, as well as ICF (FIREX).
Among these above, there may be issues related to the NIFS future plan.
Thus, it will be advisable that academic debates on the future plan should be called forth then organizedamong nuclear fusion related researchers in Japan by utilizing the national inter-university system.
(4) Fusion Engineering Researcha) General View and Achievements
I have no specific comments to say since the area is outside of my field.

b) Specific Researches (on topics)
I have no specific comments to say since the area is outside of my field.

c) F uture Plan
I have no specific comments to say since the area is outside of my field.
2. Others
I was truly impressed by the fact that under the excellent leadership of Director-General Motojima,
NIFS carried out a drastic reorganization to steadily promote the LHD project, which comprises theheart of the National Institute for Fusion Science and also that the complexity simulation research for
high-temperature plasmas were greatly extended and progressed.
Also, I got so fascinated and excited to witness that lots of excellent young researchers have been
fostered through these researches.
Now, it is my best wish that, based on these achievements, a further progress and novel development inresearch will be made under the leadership of the next Director-General of NIFS. Among other things, I
truly hope that a new academic development shall be brought forth through the collaboration with other
NINS institutes.

11

Reviewer: D
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
LHD device is the masterpiece of the art of fusion engineering.
Taking full advantage of LHD capabilities, important targets and achievements have been attained
during the last 6 years. The highlights of major discoveries are the high ion temperature accompaniedby important beneficial phenomena such as impurity hole, high density regime employing Internal
Diffusion Barrier in open helical divertor configuration, high average beta of unprecedented 5.1 % andsteady state operation of 54 minutes. These achievements resulted in the attainment of temperature offusion reactor, world record of beta value and plasma density and the world record of injected energy.
These impressive results are due to the fully integrated and coherent contributions of all teams andindividual researchers working on LHD mastered by the present leadership. Furthermore, scientific andtechnological foundations have been laid down to improve the performance even further toward thegoal of fusion.

b) Specific Researches (on topics)
Upgrade of heating capability consisting of NBI, ICRH and ECRH, the smart implementation of theclosed divertor configuration and the deuterium operation should be employed to enhance the LHD
performance even further in order to obtain simultaneously values of density, temperature andconfinement time approaching the triple product relevant for stringent fusion requirements. Also, thesteady state operation should be addressed to broaden the data base required by a fusion reactor. Highbeta can be increased even further by careful real time control of the Shafranov shift and the R ax
control. The closed divertor configuration may benefit confinement in the periphery thereby alleviating
deterioration of confinement with an increase of beta values. Also, the synergy of the closed magnetic
configuration with improved pellet injection system might yield further improvements of plasma
parameters. More emphasis should be focused on studies of momentum transport in general and inparticular on the correlation with the impurity transport. The emergence of the Impurity Hole deserves aclose attention and further extension.

c) F uture Plan
Nearest Future plans are well defined and properly funded. The physics program is well supported by awide range of diagnostics available now and coming into operation in the near future. However, amore aggressive set of goals along the lines of the present strategy of NIFS is highly desirable. The
current momentum achieving seemingly unattainable plasma parameters must be maintained. Hence,
the fully integrated approach with ambitious goals must be employed. Novel subtle methods based ontechnical and computational excellence of NIFS in order to improve plasma parameters has to besought and found. The recent successes (i.e. Li operation) obtained on smaller devices should be tested
and exploited on LHD under conditions more relevant to fusion.
(2) Simulation Science Projecta) General View and Achievements

12

During the last years significant progress in amplifying the relevance and the predictive power for LHD
experiments has been achieved. It occurs primarily due to the integration of the theory into the fabrics
of LHD decision making and the attraction of the excellence of experimental results. The division is
now focused on the fusion performance of LHD and supports major achievements carried out duringexperimental campaigns. However, Simulation Science must increase its impact by introducing many
original suggestions for novel and fine improvements of LHD. A very wide range of sophisticatedcodes has been developed with a promise to improve the fusion outlook even further. New avenues of
the LHD experiments due to come into operation are under the close attention of the Simulation Center.
The impact is further extended by the Laser Fusion Simulation project and numerical studies of theplasma material interactions. The Simulation Project coordinates works at numerous universities inJapan involved in theoretical fusion research. This activity should be the subject of enhanced attentionof SSC in order to provide an additional manpower required by a wide range of achievements of NIFS.

b) Specific Researches (on topics)
Targets encompassing the LHD relevant work are well defined. However, these must include the mosttimely and topical issues such as CDC, IDB and Impurity Holes as items of great importance.
Simulation Center should strive at playing a major role in understanding and extending theseexperimental gains by all possible means. Furthermore, models should aim at achieving a highest
possible degree of self consistency. To this end, a strong case should be made for employing the newcomputational center coming into operation in Japan for the benefit of the thermonuclear fusion
research. Publication record of the SSC is excellent. Important subjects for general science such as
self-organization, reconnection and holism project are addressed properly. These are important for the
integration into the NINS infrastructure.

c) F uture Plan
The Numerical Test Reactor project is very ambitious and should be commended. The fruitfulcollaboration and support of the ITER modeling group should be enhanced. The integration into the
LHD interpretation and the decision making must continue and become more in depth. The broad range
of issues addressed by the SSP has to be maintained.
Works should be carried out to amplify the computational power by invoking the large computer
infrastructure existing in Japan. A large reservoir of the theoretical knowledge and skills at many
universities associated with NIFS can be used to enhance the SSC impact. Scenarios focusing on theadvantages of the De operation of LHD have to be worked out.
(3) Coordination Researcha) General View and Achievements
Research Coordination Center is the first – class activity increasing spin-offs of LHD experience tomany fields of science and industry. It extends frontiers of fusion research by addressing future issues
such as tritium inventory crucial for DEMO. PWI and atomic data problems are solved thereby
benefitting present and future experiments on LHD. ITER related work is highly developed. Laser
fusion works and collaborations with National Astronomical Observatory are valuable. Outreach effortsborn out by Fusion Kids Energy Museum are highly welcomed. The CRC is a well organized entity
making it a powerful tool within the NIFS infrastructure.
PWI activity has made a significant progress and is now well poised to contribute to future plans of the
LHD and QUEST operations. Original ideas such as moving – surface plasma – facing components
both solid and liquid must be tested first on QUEST and in case of success on the LHD. Plasma
13diagnostics methods based upon modern atomic physics advances must be implemented on the LHD
and the Solar observing satellite” HINODE”. Tritium studies should be emphasized as well given the
shortage of information from other sources. R&D works employing the Microwave Steel Making
important for industrial applications should be given a high priority. Manufacturing of mirrors for ITER
is another important subject addressed by the CRC.

b) F uture Plan
The CRC pursues to enhance and further integrate its activity into the LHD activities. Collaborations
with ITER and the BA must be strengthen and broaden. Given the uncertainty of IFMIF the works on
the tritium handling must be given a special emphasis. The outreach work can be extended to othergroups of authorities and population. SC conductors for JT 60 – SA must be tested. The pioneering
work on the DEMO relevant issues has to be given a high priority. Collaborations within both NIFS andNINS activities within the context of contributions delivered by universities in Japan must be employed
given limitations of the available manpower.
(4) Fusion Engineering Researcha) General View and Achievements
FERC represents a relatively new activity addressing fusion engineering issues in depth. FERC has
made important input already by specifying most outstanding issues to be confronted by a fusion
reactor. Blanket issues based upon Flibe and Li were addressed. Tests on welding, irradiation, corrosion
and coating of V –alloy and ferrite steel were carried out. Quick feedback 3D code system is underdevelopment in order to study neutronics of a reactor. 14 MeV mockup tests are carried out albeit theirlimitations in relevance.

b) Specific Researches (on topics)
Specific research in FERC consists of blanket material systems, neutronics and magnet material
systems. Welding of vanadium alloys has been already shown possible by oxygen impurity reduction.
High purity metal vanadium was developed for V alloy large heat loads. NIFS-HEAT -2 was welded inhigh purity Ar flow to avoid impurity contamination. Degradation of fracture energy was enhanced inweld material and later recovered by post-irradiation annealing. The degradation of the quality of
welding appeared at neutron irradiation dose of 8.5 dpa. Design and feasibility studies for forced
convection loop of molten salt Flibe and liquid Li were advanced. Advanced coating technologies andthe emergence of the tritium permeation barrier have been demonstrated. Fast feedback systems were
integrated in the neutronics design. Tritium breeding under sufficient shielding has been attained.
Critical currents of varying Nb compounds were investigated after the 14 MeV neutron irradiation. Low
activation superconducting wires have invoked to enhance the electron current in V 3 Ga.

c) F uture Plan
Asymmetric and fractal geometries of surrounding structures will be addressed in collaboration with
ASIPP, China. In-situ observations during and after the 14 MeV irradiation will be carried out. All
Nb 3 Sn strands will be tested in order to facilitate ITER TF magnet fabrication. FERC issues relevant
for DEMO will be performed. Collaborations with the Oarai center of the Tohoku University on the15.5 T and 500 A current lead should be given a high priority. FERC should continue long-term creep
tests in order to investigate thermal creeps on a very long time scale. Other options relevant for DEMO
14

invoking fission experience and know-how must be sought and found.
2. Others
Present leadership has made NIFS the world-class leader at the cutting edge of fusion research.
This result has been achieved by a perfect coordination of a wide range of activities and the integrationof all activities into the main goal of thermonuclear fusion. A detailed plan has to be worked out inorder to maintain the current momentum achieved by NIFS under the present leadership.

15

Reviewer: E
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
The Large Helical Device (LHD) continues to be the flagship machine of worldwide experimental
stellarator research. LHD has achieved new record plasma parameters, though not simultaneously. It
was demonstrated very high beta (at magnetic field strength reduced to 20%) without strong
degradation by magneto-hydrodynamic (MHD) instability, ultra-high density by means of pellet
injection, fusion-relevant ion temperatures and interesting new regimes with reduced impurity
accumulation in the center. In this way, LHD continues to contribute to the physics understanding ofhelical plasma confinement. This is also of significant relevance for the international fusion project
ITER, in particular certain aspects of edge magnetic field stochastisation and MHD stability by meansof toroidal field shaping.
It is evident that LHD will remain Japan’s most important fusion device until JT-60SA goes into routine
operation. Until then the national activities in experimental fusion research will naturally focus on LHD
and may contribute to important cross-fertilization between stellarator and tokamak research.

b) Specific Researches (on topics)
The LHD device is outperforming its initial expectations. This is a great achievement and makes aremarkable contribution to the regained trust in the stellarator concept for fusion power. The excellent
plasma performance parameters were achieved thanks to optimized magnetic confinement (by shift ofmagnetic axis and by changing the plasma aspect ratio) but also to the systematic extension of theheating capabilities, namely the NBI (currently 23MW, additional 7MW are planned). Combined with
fast pellet injection, new operation regimes were discovered which allow for very high density
operation with steep edge gradients. Furthermore, interesting regimes were found where impurity
accumulation is prevented by a shielding phenomenon in the ergodic layer. In this way high density,
high pressure and – at low magnetic field – high beta plasmas could be successfully created andmaintained. MHD equilibrium and stability issues at high beta were very successfully addressed by the
team.
From the above it is evident that the LHD device is well on its way to accomplish its target values. In
addition, unexpected discoveries are made and high-level basic research is performed (in particular
MHD instabilities, Alfvén modes, zonal flows). To further pursue the excellent research on LHD, a few
recommendations may be taken into consideration:•••

The physics understanding of the discovered new regimes should be driven forward. Theinternal diffusion barrier (IDB), the core density collapse (CDC), and the impurity hole are
exciting and highly relevant discoveries. Here a systematic approach that combines theory,computer simulations and dedicated experiments would be helpful.
Electron and ion temperatures in the high density regimes are relatively low (around/below
1keV). Conversely, the temperature goals are achieved at densities that are one order ofmagnitude lower than required. Making use of the flexibility of the LHD device, integrated
scenarios should be developed in order to obtain an optimum n·Ti ·τ E.
Steady-state operation of highly powered plasmas is – besides better stability – the main
attraction of the stellarator concept in fusion research. The detailed design and the construction16

•of the closed divertor should be pushed forward as much as possible. An upgrade of thesteady-state heating power to 4MW is planned and should be available together with the fully
implemented the closed divertor.
Fusion reactor studies should be closely linked to the present DEMO studies, which are allbased on tokamaks. Here the pro’s and con’s should be highlighted. It is evident that the lack of
a Greenwald limit opens for stellarators the perspective of ignition at higher densities and lower
temperatures. It would be helpful to get a full picture of the role of thermal instabilities, neutral
particle transport, impurity generation and transport under these reactor conditions. Here the“numerical test reactor” (see below) will surely play an important role.

c) F uture Plan
The plan to explore the isotope effect by performing a dedicated Deuterium program is greatly
appreciated. This will also result in better figures of merit of LHD. The main elements of the further
development of the device are (I) the upgrade of NBI (to 32 MW) and ICRH (to 4MW) and (II) the
development, construction, and integration of a closed helical divertor. In the latter, a step-wise
approach is planned which appear to be reasonable in order to avoid a lengthy shut-down.
Recommendations:••

As soon as the detailed design of the closed divertor is available, a detailed design review withthe participation of international experts (in particular in the field of engineering) should be
conducted.
The establishment of an MHD data base is greatly appreciated. It might be of advantage toembed these activities into the formal agreements of international collaboration.

(2) Simulation Science Projecta) General View and Achievements
From the view point of the experimental researcher, the simulation science project seems to beinternationally competitive with highly regarded scientific works. As mentioned above, a dedicatedeffort to understand the newly discovered operation regimes of LHD is required. The simulation
science project of NIFS seems to be well positioned to takes these challenges.
It was very nice to see the breadth of the NIFS simulation science program: The range spans from
MHD and LHD simulations to laser plasmas to complexity in plasmas. This interdisciplinary approachis clearly in the sense of the NINS and fosters collaboration between the institutions involved.

b) Specific Researches (on topics)
No specific comments.

c) F uture Plan
For the further development of codes, e.g. in the field of turbulence and zonal flows, the access to highperformance computers is extremely important. The plans for new super computer and the NIFS plasma
simulator are very much supported.

17

(3) Coordination Researcha) General View and Achievements
NIFS remains being very well embedded into the Japanese university environment. This is obviously ofhigh mutual benefit. This is particularly the case for plasma-wall interaction, materials sciences, nuclear
sciences, diagnostics and basic plasma research. However, the coordination research center makes also
sure that the university facilities are well integrated into the LHD program, which is clearly an
outstanding achievement.

b) F uture Plan
The close contact to ITER and DEMO activities is absolutely mandatory for the stellarator community.
The coordination research centre is right to go into this direction.
(4) Fusion Engineering Researcha) General View and Achievements
The engineering aspects of LHD are already covered in (1).

b) Specific Researches (on topics)
No specific comments.

c) F uture Plan
No specific comments.
2. Others
The special review meeting was the best review meeting I ever had. It was a most appropriate summaryof the great achievements of the NIFS during Prof. Motojima’s service as the director general. His
success must be recognized and applauded. I was pleased to learn that with Prof. Komori a wellestablished a highly regarded scientist was identified to serve for the next term. I wish him all successand look forward to the next review.
The oral presentations during the review were of excellent quality. I was very impressed by quality thepresentations of the “younger generation”, Drs Sakakibara (high beta operation), Sakamoto (highdensity operation), Watanabe (zonal flows). It would be nice to see these younger scientists from the
NIFS team on international conferences as invited speakers.

18

Reviewer: F
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
LHD is an impressively large fusion experiment. It has made significant contributions to theadvancement of high temperature plasma and fusion physics, and in particular to the understanding ofstellarator / heliotron physics. The main technical achievements are the reliable operation of a complex
superconducting device. Here, I would like to specifically note the further increase of the magnetic
field. Also the demonstration of steady state plasma operation is very valuable for future developments.
Very important scientific achievements are the demonstration of high density operation with improved
confinement properties, high beta operation reaching impressive values of 5%, and plasma scenarioswith low impurity content (so-called impurity holes).

b) Specific Researches (on topics)
High density operation: To achieve high power density in a fusion reactor high plasma density is
indispensable. The internal diffusion barriers demonstrates both that stellarators / heliotrons can reachvery high densities and that a simultaneous improvement of the confinement is possible. It is interesting
to see that the density could be further increased if more heating power were available.
High beta operation: Also high beta is required for a stellarator / heliotron reactor. A volume averagebeta of 5% is envisaged, which has been achieved by LHD. Also the improved theoreticalunderstanding of the beta-limiting MHD instabilities has to be mentioned. In particular against thebackground that the theoretical predictions of the MHD stability of LHD plasma were not very
favourable, further studies in this direction have to be encouraged. In this context the adopted approachto consider the link between magnetic field topology and MHD stability, i.e. the link between stability
and equilibrium limits, should be further pursued.
Impurity transport: Impurity accumulation is one of the major issues of stellarator research. LHD has
shown that, at least under certain conditions, it is possible to avoid such accumulation. Further studies
in these direction including different plasma scenarios (high density, low density, high beta, different
plasma edge conditions, etc.) are strongly encouraged.
Diagnostics: Diagnostics were not specifically addressed. Nevertheless, I would like to use thisopportunity to mention the very good quality of the presented experimental data which are a
prerequisite for the analysis and understanding of the plasma experiments.
Altogether these results clearly show that significant progress has been made and that LHD is a major
player in the international fusion research. Besides achieving high plasma performance, the very goodanalysis based on an increasing collaboration between experiment and theory has been noticed. Thisshould be intensified. In addition, future studies should attempt a more integrated approach towards thedevelopment of high plasma performance.

c) Future Plan
Extension of heating systems and divertor:
19

The plans to extend the heating systems and to install an actively cooled divertor have been received
very positively. In particular with respect to my earlier comment about the development plasma
scenarios which combine favourable plasma properties this is a very important step. Additional heating
power is required to remove limitations in particular at high density or to extend the operational space
to high beta at higher magnetic field. This implies also a plasma exhaust which is capable of handlingmore power. Active cooling is required for steady state operation at higher power. The approach toextend the divertor in a modular way, in order to minimize the shut-down periods is fully supported.
(2) Simulation Science Projecta) General View and Achievements
Theory and plasma simulations are indispensable for the understanding of the increasingly complex
phenomena observed in fusion experiments. Here, NIFS in conjunction with their collaborators havedeveloped an impressive amount of tools and made significant advances also in first principle theory.
This includes MHD stability and plasma transport reaching from the core of the plasma to the edge.
Also the link to related fields is positively noted. Simulation science is an area which provides very
good conditions for close collaborations with university groups. The involvement of such groups iswell established.

b) Specific Researches (on topics)
An comprehensive number of research topics has been presented, including major topics in fusion
research such as turbulent transport, MHD stability, including reconnection phenomena, and plasma
wall interaction. A specific presentation has been devoted to turbulent transport, explaining that the
inward shifted configuration of LHD shows improved confinement, not only because of betterneoclassical confinement, but also because of reduced turbulent transport. This work is not only
important since it can explain experimental trends, but also because it adopts the very important issueof the relationship between turbulent and neoclassical transport.

c) F uture Plan
The LHD and magnetic confinement simulation project and the numerical test reactor project areimportant steps to develope the understanding of the running experiment and the basic properties of afusion reactor. The presented plans are strongly encouraged. More heuristic simulations and firstprinciple based theory are well balanced. The main recommendation is to further extend the link
between theory and experiment in areas such as impurity transport and MHD stability.
(3) Coordination Researcha) General View and Achievements
Fusion requires stable long-term research and development. This makes the integration of universities
for both education and participation in science and technology studies very valuable. An impressive
number of collaborative research project has been presented covering a large number of topics. The
approach to use NIFS and LHD as the centre of a large number of specific topics and research groups isthe appropriate strategy to involve universities and other research groups.

b) F uture Plan
20

Future plans, involving universities in ITER and DEMO developments, directly or indirectly via NIFS,
are strongly encouraged. Such large scale facilities and development programmes require a broad
academic basis not only for promotion of young scientist and engineers, but also for providing
acceptance in the general population. In this context, it is very good to see that already the youngest
generation is introduced to the topic of fusion research.
(4) Fusion Engineering Researcha) General View and Achievements
A very ambitious development plan for DEMO has been presented. The presented technology topics
cover the main areas which need to be further developed: Blanket material system, neutronics, andmagnet material system. The plans to construct systems which test as far as possible the integration of
the individual components are strongly supported. For future discussions a more detailed analysis how
the development plan depends on the ITER and IFMIF schedules, including decision making
requirements, would be helpful.

b) Specific Researches (on topics)
Blanket material system: Interesting new results were presented indicating potential solutions for theblanket technology. A dedicated presentation explained the development of a liquid breeder blanket. In
addition to the excellent presentation the main impression was that this research area is benefiting fromvery good collaboration work and a healthy nuclear industry. For the future a system integration forfeasibility studies on the compatibility of hydrogen recovery and heat exchange in a flowing system isplaned, which is strongly supported. It is recommended to further elaborate the plans to eventually test
such a blanket on ITER.
Neutronics: The design of the FFHR is based on 3D neutron calculation for tritium breeding andneutron screening. It is very encouraging to see that these calculations are validated by DT neutron
irradiation measurements. Future plans comprise improved neutron calculations for complicatedgeometries and further validation measurements.
Magnet material system: The effect of neutron irradiation on the magnet performance (critical magnetic
field) has been discussed in detail for various types of superconductors. Future work will also include
high-temperature superconductors, which is strongly encouraged, as this would significantly alleviate
the requirements for the cryogenic systems.
2. Others
Finally, I would like to express my gratitude for the opportunity to take part in this special review. Not
only did I learn a lot about NIFS and LHD, but I also enjoyed the very high quality of the presented
work and the well-founded discussions. The younger researches taking part in this review demonstrated
that NIFS is well prepared for the future. Sending these young researchers to major conferences should
be encouraged.

21

Reviewer: G
1. Outline
Upon the establishment of the National Institute for Fusion Science (NIFS), a task force consisting ofmajor researchers in Japan was placed under the Nuclear Fusion Group in the Academic Council todebate on major plans carried out in NIFS, and a series of in-depth discussions were made.
It was then concluded to pursue the following: 1) to adopt torus plasmas that were being conducted
research with largest numbers of researchers on a global scale and that were best acknowledged
academically at that point, and among those, to adopt the external conductor system that had ahigh-flexibility in the magnetic field configuration setting; and 2) to carry out the research in the torus
plasma confinement physics including tokamaks.
The NIFS LHD research was first started from the device technology development including thesuperconducting magnet technology, and the LHD construction was successfully carried out based on
the experiences in constructing another devices and their results. After that, a desired design andconstruction, studied from a broad perspective, were smoothly progressed; now, the device is making
outstanding research achievements as the world leading large-scale torus device. This situation fits theinitial expectations. As a person who has been witnessing the progress of its research ever since its
start-up, I would like to begin my report by stating that the review of this time was extremely asatisfactory one with nothing to betray my expectations.
2.

Large Helical Device (LHD) Project

The record of their steady-state operation (namely a high-ion temperature of 5.2 keV, high-density of
1.2×1021m-3, and a high β value of 5.1 %), which was achieved as its major research plan in NIFS, oneof the Inter-University Research Institutes, under the proper research programs, should be highly
evaluated as well as especially noted. Moreover, NIFS did not just pursue those data excellent as arecord but that the institute made such notable achievements through a series of research andexperimental campaigns to execute its original mission, which was to thoroughly research in the torus
confinement characteristics as described above. This must be highly admired.
3.

Activities as an a Inter-university Research Institute(1) Simulation Science Project
While it is essential for NIFS to play its role as the inter-university research institute in executing theinstitute’s major plan addressed above as a matter of course, it is also desired that NIFS will makecontributions to the entire field of fusion researches.
First of all, the simulation science to fully utilize the benefit of a rapid hardware / software progress
made in the recent computer science is an important research method in the fusion researches. Besides,
it will be a critical mission as the inter-university research institute for simulation researches to makethe progress by communicating with wide fields deeply related to fusion researches.
Especially in the fusion research as a big science, simulation is also important method to apply its
achievements to the confinement researches in other configurations like tokamaks by not only
understanding the results of experimental research and predicting experimental results in the major planin NIFS but also by analyzing its confinement characteristics.
In order to achieve the scientific results, except for simply utilizing the computer hardware performanceas well as the ordinary software technology; the development of simulation methods based on
characteristics inherent to fusion plasmas is extremely critical. Thus, the ability for that aspect is22

desired.
The theory and simulation science research in NIFS are evaluated as a quite high level, and theachievements up to now fully satisfied our initial expectations.

(2) Coordination Research
In a way, it is the matter of course that any major research like the nuclear fusion science, where a
grand-scale budget is required, is expected to contribute to varieties of related areas of research alongwith the execution of its main plan. Therefore, a role of the newly established Coordination ResearchCenter is much expected.
At the same time, it must be quite challenging to extract effective tasks among many related areas ofresearch from a broad scientific, technological, or industrial perspective.
The newly established Coordination Research Center is extracting interesting topics and enabling theeffective collaborative researches by surveying a broad field of research that deeply relates tosurrounding areas as well as the industrial application. This will surely enhance the NIFS significanceas the inter-university research institute, and thereto, possibly enhance a reputation toward the entire‘new energy source development research project’ called ‘nuclear fusion’. I should say that this new
development deserves a special attention.
Now, a further development in this area is much expected.
By the way, the area of atoms and molecules in plasmas has been globally acknowledged as one of
NIFS activities in the related fields. Though it may not be boldly recognized from the aspect ofapplications, the area of atoms and molecules has been making series of important achievements not
only as a foundation to support various scientific technologies, namely many different industrial
technologies like material science or diagnostic technology, but it has also built up a critical knowledge
as a foundation of many academic fields.
Because of its rather unimposing existence, one may have to understand that no grand report was notmade for their achievements this time; yet, I still cannot help hoping that they would further improvethen develop their existing precious accumulations.
4.

OthersFour presentations in the “Recent Research Report, Topics” by 4 young researchers in the afternoon
were truly impressive since they proved that excellent young researchers were steadily brought up. It
must be, needless to say, a wonderful opportunity for any young researchers to engage in their researchin a great environment like NIFS.
Yet, I’ve seen many times that because of the severity of ‘reviews’ given to research, young humanresources were wasted and the difficulty arose as to the improvement of promising young talents. Also,
I often hear more than a few voices wondering whether such distinguished researchers who can be
responsible for the academics in the future could really be fostered under such circumstances.
The fact that NIFS is in the process of successfully fostering such talented researchers definitely proves
the healthiness of its research activities.
Thus, I should comment in addition that the future of nuclear fusion studies in Japan much depends ontheir effort.
5.

Summary23

As I have stated above, research activities by the National Institute for Fusion Science have madeoutstanding achievements as one of the leading magnetic field confinement nuclear fusion research in
the world.
Their research fully satisfied our expectations, and thus it should be highly regarded.
6.

ExpectationsFirst of all, it is advisable that the present activity should be continuously carried out for further
development as one of the major streams of the magnetic field confinement nuclear fusion research by
the use of large-scale devices in the world.
On the other hand, the global trend is not necessarily focusing on the magnetic field confinement
nuclear fusion only. It should be specially noted that in the Asian region, centers for the inertial
confinement fusion research were constructed in China and Korea, respectively, to perform aggressive
research activities.
The inertial confinement fusion research in Japan has been mainly carried out in the Institute of Laser
Engineering (ILE), Osaka University up to today. Well, especially these days, many research groups
have taken notice of the fast ignition developed by ILE, following them to carry out research along with
the new development. Unfortunately, the fact is that it is not easy at this point for universities in Japan
to compete each other on these activities.
Finally, I earnestly hope that NIFS will quickly devise a plan concerning how to deal with the inertial
confinement fusion research in NIFS as the future nuclear fusion research plan in our country andmoreover that the institute will consider adopting it as one of the NIFS plans.

24

Reviewer: H
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
In General, the Large Helical Device Project has come long way after the “First Plasma”, and it is now
very mature fusion research program and leading experimental program world-wide. In my opinion, it
is entirely due to leadership of NIFS and LHD Project, as well as dedicated professional staffs andtechnical members of the LHD Project. The LHD Project also provided and enhanced collaboration
with domestic as well as international researchers and institutions for effective scientific program
execution and human resource development in fusion science. It is also worthwhile to recognize the
LHD experiment produced well-qualified world-class scientists by providing training and education inreal world setting.
With new perpendicular NBI addition, the achievement of high ion temperature with high density isvery impressive advancement since last review. In this series of experiment, the improvement of ionheat transport is attained level of neoclassical transport.
The achievement of high beta 5.1% and sustained value of 4.5% in steady-state, is also beyond initialdesign value as well as expectation. Detailed study of magnetic configuration and topology of flux
surface has made such impressive achievement possible.
Along with high ion temperature experiment and high beta study, the achievement of high density, highpressure discharge due to internal diffusion barrier, is also very important progress. The measured
diffusion coefficient under very high density gradient condition is studied very detailed manner.
In steady-state operation study, the control of heat-load on divertor plate as well as improvement ofdivertor plate heat conductivity had proven to be effective, so that the future planed upgrade could be
more conclusive.
In conclusion of general view and achievement section of LHD Project, the achievements on ion
temperature, electron temperature, higher-beta, electron density, and steady-state operation, all aresurpassing initial expectation of LHD experiment targets, even though the operation of LHD is still
moving forward strongly. So we could expect even better results after planed upgrade.

b) Specific Researches (on topics)(i) High-Beta Research with 3D MHD Characteristics
As noted in general section, the high-beta study in LHD showed very high level of depth and maturity
in all issues including MHD equilibrium, MHD stability and transport. The MHD equilibrium study
with magnetic axis, aspect ratio variation compared with equilibrium topology, showed way to achieve
higher-beta and way to avoid equilibrium beta-limit.
In MHD stability area, the study showed the clear dependence to the magnetic Reynolds number. Also
the linear stability study made distinction from the resistive interchange mode stability prediction fromreal experimental environment. The ideal modes such as Mercier mode, low-n interchange mode,
high-n ballooning mode, had been studied in detail. It derives possibility of common understanding of25

characteristics if MHD stability and relation to profiles as well as confinement.
(ii) High Density Operation
For achieving high density plasma, fueling with pellets and particle control has been studied in LHD.
The results with various pellet injection methods also presented. In this high density study, the LHD
Internal Diffusion Barrier plasma is produced with high density gradient. The reproducibility of IDB
shots has been demonstrated and the transport properties of IDB shots had been studied in detail
In the high density study, the highest density is achieved and quasi-stationary sustainment of highdensity shots had been achieved by using repetitive pellet injection. The results showed way to
improvement in future planned upgrade, as well as reactor studies.

c) F uture Plan
In planned near term upgrades, the upgrade of heating capability in NBI, ICH and ECH is deemed very
important to continue progress of LHD experiment that has been demonstrated in various areas. Also,
the deployment of closed helical divertor would be very important to achieve better handling ofparticles and heat load to the plates.
The experimental capability with deuterium fuel would be very good compliment to the alreadyimpressive capability of LHD by providing tools for isotope effects.
(2) Simulation Science Projecta) General View and Achievements
In the report, the three major simulation efforts have been reported. The first effort, that is LHD andMagnetic Confinement Simulation with Numerical Test Reactor, is the most important among all three.
The impressive progress in this first effort made LHD experiment much more consistent and strong infinding way to improve in the recent years. In my opinion, the fast growth in simulation area
contributed and will contribute significantly to better understanding of experimental results as well as
finding innovative new approach to the better performance of LHD experiment in future. It is also verymuch noted that the theoretical study and turbulence simulation worked very well and good feed-backto each other. These efforts will, no doubt, contribute to the LHD experiment and better understanding
on confinement, so that the improvement on the target values.
It is worthwhile to noted that the fast ignition simulation of laser fusion, PIC-MHD simulation ofmagnetic reconnection phenomena, and PIC-MD simulation of plasma material interaction had madevery good progress.

b) Specific Researches (on topics)
In Magnetic Confinement Simulation Project, the hierarchy-extended simulation with core-plasma fluid
model, core-plasma kinetic model, and peripheral plasma model, as well as hierarchy-integrated
simulation, have been presented with very strong progress and impressive results. Especially, thedevelopment of TASK3D code and application to the LHD Plasma analysis showed very important
progress for future synergy between simulation and experiment.
The turbulence transport and zonal flow simulation showed NIFS’ leading role in this effort in theworld together with very strong collaboration with other leading groups. The fast growing capacity is26

very impressive and we would recommend to encourage higher priority in support.

c) F uture Plan
The proposed future plan in magnetic confinement simulation project seems well posed. The
improvement of hierarchy-extended simulation and integration to the level of numerical test reactor
will be very challenging but worthwhile effort. It is recommend to make progress in turbulencesimulation for particle transport, momentum transport along with electron transport studies in thepresent level of ITG related turbulence simulation.
(3) Coordination Researcha) General View and Achievements
In very short time, the Research Coordination Center made very good progress in many areas ofcooperation activities, including Universities, Industries as well as other Research Institutions. The
renewed efforts in atomic-molecular and edge-plasma data group made good results in plasma-wallinteraction, moving-surface PFC studies, and plasma diagnostics using impurity ions.
The industrial cooperation with spin-off technology made big progress in many applications of
microwave technology.
The cooperation with other research institutions including ZPF ceramics for large telescope is worth
noting for fusion spin-off application.

b) F uture Plan
The future plan for two cooperation areas such as industrial application and other research institutions
is extension of what has been done, so far. But it would be recommendable to extend technologies aside
from microwave application. The LHD has many other advanced technologies that have many spin-off
potential, so it would be worthwhile to pursue systematic approach to cultivating new applications.
It is also recommendable to engage in much stronger way in ITER cooperation as well as BA. Withaccumulated engineering capability and technology know-how’s, NIFS is uniquely qualified tocontribute ITER and BA project’s success. Therefore, the institutional priority to ITER engagement
needs to push higher than up to now.
(4) Fusion Engineering Researcha) General View and Achievements
The main thrust of the Fusion Engineering Center is consisted with three areas including blanket
material, neutronics and superconducting magnet materials. The blanket material system area has madesteady progress with solid results. Neutronics area is now producing results. The superconducting
magnet material area now produced important contribution to the neutron irradiation studies.

b) Specific Researches (on topics)
In specific contribution of FERC, the development of long-life liquid blanket is presented. The ITER
27

TBM related research including V-alloy, and Flibe, made steady progress. The detailed study anddevelopment is in progress.

c) F uture Plan
The future direction of FERC’s research plan is well placed to the system integration toward DEMO
Reactor. However, the more effort and higher priority needs to be placed toward neutron material
studies such as IFMIF or other neutron source.
2. Others
In concluding Special Review, the recognition of Professor O. Motojima’s leadership to achieve thisfar, is on order. His contribution to the design, construction and operation of LHD before his DG
position is well-known for long years, now. However, the his legacy of the six year tenure of NIFS DG
is so distinguished, so the peers and followers would have very hard time to match in the future.
However, I strongly believe that the leaders of LHD experiments and younger generation scientists andengineers in NIFS will move into new territories of LHD experiment and beyond. To achieve thiseffectively, it will be important to have leadership with future vision, and empowerment of more active
younger generation in leadership role.
Again, I am very honored to review such wonderful organization with leader like Professor Motojima.

28

Reviewer: I
1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD) Projecta) General View and Achievements
The plasma performance that has been achieved in the Large Helical Device (LHD) is most impressive.
The target parameters for electron temperature and density, ion density, steady-state operation discharge
time, and volume-averaged beta have all been either achieved or surpassed. The central ion temperatureachieved to date (5.2 keV) is about half of its target (10 keV); it is to be noted, however, that a central
ion temperature of 13.5 keV has been achieved with Argon gas.

b) Specific Researches (on topics)
The upgraded heating provided by the new 7 MW, 40 keV perpendicular neutral beam has resulted inhigher ion temperature and improved ion thermal transport. Very interestingly, LHD also finds that, as
the ion temperature gradient increases, a carbon impurity “hole” is formed, due to outward convection.
The convection is apparently anomalous, contradicting neoclassical theory. This impurity hole is quite
an impressive effect.
Also extremely impressive is the attainment of high volume-averaged beta (5.1% maximum, with 4.8%
sustained for 85 energy confinement times and 4.5% sustained for 150 energy confinement times). The
continued increase in achieved beta values with additional auxiliary heating is very promising forhelical confinement systems.
The ultra-high density results achieved in LHD with the “internal diffusion barrier” are important inthat they offer the possibility of a route to a force-free helical reactor. (This was a major topic ofdiscussion at the 2008 International Toki Conference.) The continued optimization of pellet fueling is anecessary research topic for pursuing a high-density reactor scenario.
Transport in the ergodic layer at the plasma edge in high-density and high-beta LHD plasmas is an
important research subject. The 3D edge transport code EMC3-EIRENE has been used to analyze theexperimental data.
The measurement of fast-ion loss with scintillator probes, particularly in combination with code
simulations of Alfven eigenmode-induced fast ion transport, has resulted in very nice data that is wellinterpreted.
I very much appreciated the specialized talks on high-beta MHD experiments (presented by Dr.
Sakakibara) and on high-density operation for helical reactors (presented by Dr. Sakamoto). The lovely
comparisons of experimental data with simulation results in both of these talks were especially welldone. For example, the achievement of high precision MHD codes that allow the study of high-nballooning modes has led to greatly improved predictions. In both talks, clear statements of next-stepresearch plans were provided. Definitely I would encourage similar in-depth talks on special topics atfuture External Peer Review Committee meetings.

c) F uture Plan

29

The LHD has four near-term future plans: (1) upgrading the auxiliary heating—in particular, adding a
fifth neutral beam line, (2) installing a closed helical divertor, (3) operating deuterium plasma
discharges, and (4) continuing the design study for the force-free helical reactor. These are important
steps for moving forward and should be pursued vigorously. It would be interesting to hear more details
about these future plans at a future External Peer Review Committee meeting.
(2) Simulation Science Projecta) General View and Achievements
The Department of Simulation Science has been very productive, with many results, invited talks, andpublications. Consequently, the overview presentation on simulation science had to cover too many
research topics, with little detail. The afternoon in-depth talk, however, compensated for this.
Particular examples of excellent research are the gyrokinetic simulations, multi-scale interaction
between micro-turbulence and macro-MHD; energetic particle simulations; collisionless reconnection;and laser fusion simulations that led to new target designs for Fast Ignition.
The Department of Simulation Science appears to have good collaborations with the LHD Theory andData Analysis Division. Collaborations with outside groups and scientists are also strong. In particular,
I note a number of excellent papers written jointly with the JIFT visiting professors in recent years.
The annual Symposium on Simulation Science, which has now been held for two years (2007 and2008), is developing into a solid meeting. The 2008 Symposium attracted 90 participants.
The replacement supercomputer (77 TFlop, 16 TByte) for simulation science was successfully selected
and announced in September 2008. It will begin operation in March 2009. No doubt it will be put toheavy use for the Numerical Test Reactor Project.
As I had pointed out last year, the terminologies “hierarchy-extended,” “hierarchy-integrated,” and“hierarchy-normalized” are unclear. My suggestion is to use terminology that is more internationallyaccepted and understood.
With its world-class expertise in simulation science, it might be advisable for NIFS to participate in the
Integrated Modeling Expert Group that is being newly formed for ITER.

b) Specific Researches (on topics)
The research on gyrokinetic simulations is internationally recognized as first class, as evidenced by the
many recent publications (including a Physical Review Letter last year) and also by its having been
selected for invited talks at three major international conferences in CY 2008 (American PhysicalSociety, International Congress on Plasma Physics, and IAEA Fusion Energy Conference). The
in-depth specialized talk on this research (given by Dr. Watanabe) was very well presented. Of
particular interest, it has been found that inclusion of the radial drift motion of the particles trapped inhelical ripples now leads to ITG heat transport results for inward-shifted plasmas that are in close
agreement with the experimental observations. I recommend that these gyrokinetic simulations are now
at a stage where specific experiments could be proposed on LHD to test its theoretical predictions. The
proposed research on ETG turbulence and zonal flows is important. Studies of momentum transport andanomalous particle transport, in addition to heat transport, would also be advisable.
Considering the importance of the divertor to LHD high-density operation and of the ergodic surface
30

layer in high-beta operation, it would be useful to strengthen the theoretical/simulation research on
boundary plasma physics. In particular, the 1-D fluid modeling in the divertor leg for LHD should be
extended to two or three dimensions and generalized to include kinetic effects.
For the laser simulations of FIREX, the new ideas of pre-pulse heating and additional foam in the coneshould result in significantly improved performance.
Using the magnetic reconnection simulations to attack a real-life problem (viz., magnetosphericsubstorms) is commendable. Another significant real-life application for reconnection simulations
would be solar coronal loops.

c) F uture Plan
There are 14 targets in the Mid-Year Plan for the LHD and magnetic confinement simulation project.
These targets are all reasonable. It would be helpful to hear more about how “hitting” these targets
would impact LHD operation and/or understanding.
The Mid-Year Plan targets for the laser simulation project seem quite ambitious, especially in view ofthe fact that only one scientist at NIFS works on this project.
The Mid-Year Plan targets for the plasma complexity simulation project are reasonable.
The goal to develop a Numerical Test Reactor is exceeding ambitious. In addition to the flow chart
describing this an all-encompassing code, it would be helpful to see a set of clearly defined concrete
steps for the near-term plan.
The LHD experimental program is producing novel results—e.g., impurity holes, density barriers, ultrahigh beta operation—with interesting physics aspects, which could be clarified with simulations andtheoretical interpretation. I recommend that the Department of Simulation Science continue toemphasize pursuing such studies.
(3) Coordination Researcha) General View and Achievements
The Coordination Research Center carries out a rather wide spectrum of interesting activities.
The internal structure of the Coordination Research Center was somewhat re-organized in 2008, withthe conversion of the atomic and molecular effort from a Data Research Center into an Edge Plasma
Data Group, the addition of a group on basic innovation science and technology within the Division ofIndustrial-Academic Research, and the addition of a new Division of Science Communication (which
includes the new Fusion Kid’s Energy Museum). In the revised organizational structure for the
Coordination Research Center, it is unclear whether the terms “collaboration,” “coordination,” and“cooperation” have different or identical meanings.
In the area of plasma-wall interactions, the Coordination Research Center has a study on liquid andsolid lithium moving-wall concepts. It would be interesting to hear how this study differs fromcorresponding investigations of lithium plasma-facing components by other world research groups.
Also, it’s not clear what are the new results; the most recent reference is to a paper by Nagayama thatwas presented at the 2008 Symposium on Fusion Technology (but he is not listed on the Coordination
Research Center web page as a Center member).
31

The work on developing collisional radiative models for impurity ions is relevant to diagnostic
measurements at the plasma edge in LHD. These models are said to form the basis for external
collaborations to analyze solar plasma data.
The work on developing tritium recycling simulations that incorporate plasma physics, materials
science, and atomic and molecular physics could be critically important for ITER and other burning
plasma experiments. Two papers on this subject, presented at the recent PSI and ICPP conferences,have been accepted for journal publication. More work in this area would be advisable. Perhaps the
Coordination Research Center activities on plasma wall interactions and on tritium inventory andrecycling could be coordinated with similar activities in the Fusion Engineering Research Center.
It’s a bit confusing why the FIREX fast ignition simulations, already reported (as a collaborative effort)in the presentation concerning the work of the Department of Simulation Science, should also be
included in the Coordination Research Center presentation.
The investigation of microwave sintering techniques for novel ceramics constitutes a major portion of
the work done at the Coordination Research Center. This work has important applications for theconstruction of the mirror for the next-generation Extra Large Telescope. This work has also led to theestablishment of significant collaborations with industry. Noteworthy in this connection are the Monte
Carlo simulations on energy released by magnetic field changes, which led to the discovery of a very
interesting result about the vanishing of spontaneous magnetization above the Curie temperature.
NIFS is to be commended for sponsoring the Fusion Science Archives, in which so far 18,000
documents have been collected. It is unclear why the number of events in the database, which had been
increasing monotonically from about 1997, abruptly fell after 2005.
The Kids Fusion Science Museum, which began operation in late 2008, is an interesting new outreachprogram sponsored by NIFS through the Coordination Research Center. Personally, I walked throughthe exhibition room in the NIFS lobby and enjoyed looking at the various exhibits. I expect thatstudents from local schools are similarly fascinated with the exhibits, as well as with the tours of the
LHD device and the virtual reality simulation center.
The new course on “Science Communication” for teachers is also an excellent idea.

b) F uture Plan
Except for a sentence about planning to develop a collisional-radiative model to examine solar coronalheating, no clear statements were provided about future plans. Presumably the current work describedin the presentation will be continued forward.
(4) Fusion Engineering Researcha) General View and Achievements
The Fusion Engineering Research Center (FERC) is well equipped with good facilities, which will help
to advance collaborations with university research groups.
The FERC is currently engaged in seven collaborations with groups at Japanese universities, in addition
to working with scientists in other departments at NIFS on LHD engineering problems, on theforce-free helical reactor, and on safety and cost evaluation. The increased emphasis on FFHR reactor
32design issues, especially blankets and irradiation, is commendable.
The FERC appears to be well managed.

b) Specific Researches (on topics)
In the area of blanket material systems, new results have been obtained for the welding of vanadiumalloys, for forced convection of molten salt Flibe and liquid lithium, and for advanced coating
technologies. Noteworthy was the young scientist award received from the Japanese Atomic Energy
Society for the work on confirming the low corrosion rate of steel in high purity Flibe. The in-depth
talk about the development of long-lived liquid breeder blankets (presented by Dr. Nagasaka) was quite
interesting.
In the area of neutronics, both simulations and experiments are being performed. Importantly, thisallows for validation of code modeling for Test Blanket Module and DEMO reactor designs.
In the area of magnet material systems, collaborations with universities, industry, and other national
laboratories (NIMS and JAEA) are exploring the effect of neutronic irradiation on superconducting
magnet materials.
I appreciated the tabular presentation about the number and various types of papers published during
the past three years. For only having a staff of 7 scientists along with 3 students, the FERC haspublished prolifically during the past three years. Many of the papers were joint collaborations. The
FERC has apparently made a conscious effort to promote the writing and publishing of papers.

c) F uture Plan
Future plans were clearly presented for the three research areas of blankets, neutronics, and magnets.
2. Others
The National Institute for Fusion Science has a well-articulated statement about its three-fold mission
goals. These goals are to carry out (1) research—experimental, theoretical, and engineering; (2)collaborations—national and international; and (3) training—graduate students and young researchers.
Overall, NIFS is strongly fulfilling all three parts of its mission. The FY2004-09 Mid-Term Plans for
the Large Helical Device project, for simulation research, and for fusion engineering are clearly stated.
(It would be useful if there were also a similar statement of Mid-Term Plans for coordination research.)
The number of staff at NIFS increased marginally (2%) in FY 2008, compared to FY 2007. The budget
decreased slightly from last year (less than 0.5%, which nevertheless amounted to 41 MYen in realmoney).
The number of research topics (and the number of collaborators) for general collaboration research,
LHD collaboration research, and bilateral collaboration research all increased somewhat over thecorresponding numbers for the previous year. However, the funding dropped slightly (by 21 MYen).
Interestingly, the total number of universities and institutes involved in collaborations with NIFS
decreased 8% from 157 to 144.
During 2008, no new governmental international collaborations or scientific agreements with foreign
universities or institutes were established. Six of the former and 14 of the latter had previously been33

established, and this is already an impressively large number.
The number of students who are being trained through the Graduate University of Advanced Studies
has remained constant, compared to last year, as have the number of students from associateduniversities doing degree work at NIFS and the number of student researchers working at NIFS throughcollaborative projects. The number of students from associated universities taking courses at NIFS has
dropped by 50%. In 2008, the ITER International Summer School was held in Japan.
I appreciated the provision of 12 recent NIFS publications, as background information to thepresentations at the meeting.
I recommend the inclusion of metrics in the overview presentations at future External Peer Review
Committee meetings as measures of progress and activity for LHD, simulation science, researchcoordination, and fusion engineering. Examples of such metrics are the number of number of publishedpapers, invited talks, patents, students graduated, collaborations, etc.). I have the impression that the
NIFS publication record has been continuously increasing every year. The NIFS presence at the recent
IAEA Meeting in Geneva was certainly very strong.
The excellent in-depth talks in the afternoon—very clear, very well organized—by the (comparatively)
younger scientists bode well for having highly qualified staff members in the future at NIFS. Actually, I
suspect that NIFS could have easily scheduled twice as many such talks, all reporting results at thesame high level of achievement.
I have nothing but praise for Prof. Motojima as the NIFS director-general for the past six years. The
Large Helical Device is now the best helical confinement fusion device in the world. NIFS is aworld-leading center of excellence in fusion science, with a program that integrates experiments,
theoretical simulations, and fusion engineering. The next director-general of NIFS will inherit an
Institute that is functioning efficiently and productively, thanks to Prof. Motojima’s outstanding
leadership.

34

3.

Brief Summary

1. Project Activities(Research objectives, Results and Topics, Research Quality, Suggestions for Improvements)(1) Large Helical Device (LHD ) Projecta) General View and Achievements- The achievements of LHD project are very impressive and cover all the main issues for the
successful development of fusion energy.
- The highlights of major discoveries during the last 6 years are the high ion temperature accompanied
by an impurity hole, ultra-high density operation, high average beta without strong degradation by
MHD instability, and steady state operation. These are promising results for helical confinement
systems.
- Physics study has been emphasized, which is surely based on the NIFS’s mission originally given at
its establishment. They have also contributed to the progress of comprehensive understandings oftoroidal plasmas.
- Reliable operation of a complex superconducting system is a great technical achievement.
- The LHD project has provided and enhanced collaborations for effective execution of science
program and human resource development in fusion science.

b) Specific research- The excellent plasma performances were achieved by optimizing magnetic configuration and thesystematic extension of the heating capabilities. Combined with fast pellet injection, new operation
regime, disruption-free high density operation, was discovered.
- Interesting regimes were found where impurity accumulation is prevented.
- MHD equilibrium and stability issues at high beta regime are very successfully addressed. It is
recognized that good quality of diagnostics has driven the progress of the analysis and theunderstanding of the plasma experiments.
- Upgrade of heating capability, the smart implementation of the closed divertor configuration and thedeuterium operation should be employed in order to extend the steady-state operation and to
approach the triple product relevant for stringent fusion requirements.
- The physics understanding of new discoveries, such as internal diffusion barrier (IDB), the coredensity collapse (CDC), and the impurity hole, should be driven forward. More emphasis should be
put on momentum transport and in particular on the correlation with the impurity transport.
- Beta value can be increased even further by careful real-time configuration control.
- The measurement of fast-ion loss and the corresponding simulations has resulted in very wellinterpreted nice data.
- Reactor studies should be closely linked to the present DEMO studies. It is evident that the lack of aGreenwald limit opens the perspective of ignition at higher densities and lower temperatures. It
would be helpful to get a full picture of the role of thermal instabilities, neutral particle transport,
impurity generation and transport under these reactor conditions.

c) F uture plans- Nearest future plans, such as the deuterium experiments, upgrade of the heating capability, closed
helical divertor and continuation of the design study for the force-free helical reactor, are welldefined.
35

- A step-wise implementation of a closed helical divertor is well planned not to affect the experimental
schedule.
- It is recommended that all efforts should be made to take the machine to its physical limits.
- Novel subtle methods based on technical and computational excellence of NIFS has to be sought andfound to improve plasma parameters.

(2) Simulation Science Projecta) General View and Achievements- It is highly evaluated that the simulation group has grown up so as to develop three projects inparallel. Especially, LHD and magnetic confinement simulation project has steadily achieved
internationally-competitive and highly-regarded results. The fast growth in simulation research has
contributed and will do so to better understanding of experimental results and to find the better
performance of LHD in future.
- It is the right way to develop “The Numerical Test Reactor Project” by integrating these activities
and heavily utilizing the replaced supercomputer.
- The impact is further extended by the laser fusion simulation project and numerical studies of theplasma material interactions.
- These projects taking the interdisciplinary approach coordinate related works at numerous
institutions.

b) Specific Researches (on topics)- Research on ITG turbulence and zonal flow formation in helical plasmas is remarkably progressed. It
has been clarified that the zonal flow is kept with higher amplitude in a configuration with smaller
neoclassical transport. The effect of radial electric field has also been investigated. These simulations
are now at a stage where specific experiments could be proposed on LHD to test its predictions.
- The development of TASK3D code and its application to the LHD experiment showed very
important progress for the future synergy between simulation and experiment.
- Inclusion of quite detailed diagnostics data could be a good addition to the present excellent
simulation results.
- Comparison with tokamaks should be taken into account.
- Targets encompassing the LHD experiment are well defined. These must include the most-timely andtopical issues such as CDC, IDB, impurity hole and momentum transport.
- Important subjects for general science such as self-organization, reconnection and holism project are
to be integrated into the NINS infrastructure.

c) F uture Plan
- The Numerical Test Reactor project should be commended with a set of clear defined concrete steps
for the near-term plan.
- The fruitful collaboration and support of the ITER modeling group should be enhanced.
- Scenarios focusing on the deuterium operation have to be worked out.
- The plans for new supercomputer are very much supported.
- It is strongly hoped that these simulation projects will play the pioneering role to promote theintegrated research on hierarchical phenomena in a wide range of fields.

36

(3) Coordination Researcha) General View and Achievements- Coordination Research Center is well-organized and performing the first-class activity increasing
spin-offs of LHD experience to many fields of science and industry. This is particularly the case foratomic-molecular process, plasma-wall interaction, materials sciences, nuclear sciences, laser fusion,
diagnostics and basic plasma research.
- Outreach efforts such as “Kids Fusion Energy Museum” are highly praised.
- The new course on “Science Communication” for teachers is also an excellent idea.

b) F uture Plans- Close contacts such as with ITER and BA, JAEA and ICF (FIREX) research are strongly
encouraged. The pioneering work on the DEMO relevant issues has to be promoted.
- Tritium handling issues must be given a special emphasis.
- Further progress of atomic-molecular database activity should be emphasized as the basis of a wide
range of scientific fields.
- The LHD has many advanced technology with spin-off potential to pursue systematic approach tocultivate new application.
- The outreach can be extended to other groups of authorities and population. These will be related to
the future plans of NIFS so that discussions with related community should be promoted by
exploiting NIFS’s inter-university framework.
- It is also recommended to clarify the final object of each research topic, and what kind of“Boomerang” effect has been obtained.

(4) Fusion Engineering Researcha) General View and Achievements- The research subjects were very well chosen and the obtained results are world-relevant. FERC
(Fusion Engineering Research Center) has obtained important results by specifying most outstanding
issues towards a fusion reactor, such as blanket, neutronics and magnets.
- Specification of the expected scale of a reactor would be worthwhile to understand theirachievements.

b) Specific Researches (on topics)- Researches in FERC consist of blanket material systems, neutronics and magnet material systems.
Long-life liquid Flibe and Li blanket studies were impressive.
- NIFS-HEAT-2 was welded by avoiding impurity contamination.
- Fast feedback systems were integrated in the neutronics design. Neutronics studies are welcome inview of the approaching ITER operation.
- Developed results of superconductors are evaluated to be at high-level.

c) F uture Plans- Collaborations should be further promoted such as issues on the geometries of surrounding37

structures, and on the current lead.
- It should be continued long-term creep tests in order to investigate thermal creeps on a very longtime scale.
- Improvement of neutron calculations for complicated geometries and further validation
measurements and study on the high-temperature superconductors are expected.
- More efforts and higher priority needs to be placed towards neutron material studies such as IFMIF
or other neutron source.
- More detailed analysis how the development plan depends on the ITER and IFMIF schedules would
be helpful.
- The plans for helical reactor and comparison between tokamak and helical reactors are expected.
2. Others- Outstanding leadership of Director-General Prof. O.Motojima has made NIFS the world-class leader
at the cutting edge of fusion research. These results have been achieved by a perfect coordination ofa wide range of activities and the integration of all activities into the main goal of thermonuclear
fusion. They covered not only the world-relevant experimental results in LHD and simulation
sciences, but all the accompanying programs in science, collaborations with many institutions,
technology programs and public relations programs.
- The presentations were of the excellent quality. The quality of younger generation’s presentations isimpressive. It is very encouraging to see they have been producing world-class results. It
demonstrated that NIFS is well prepared for the future. It would be recommended that for the next
review, special thought be given as to how to maintain such momentum and world leadership for thelong term.
- Further progress of NIFS research and the germination of the new scientific paradigm are expectedbased on the present achievements and further extended collaborations.

38

(a) Translation into Japanese
和訳

In the case the reviews submitted in Japanese, the original text contents are included here and thetranslation of them into English is included in the main chapter (2. Reviews on NIFS Research Activities).
一部、オリジナルが和文のレビューがありましたが、このオリジナルを和訳に収録させていただき、その英訳を本文 (2. Reviews on NIFS Research Activities) に収録させていただきました。

目

次

1.

核融合科学研究所の研究活動に関する評価 ････････････････････････････ a-1

2.

評価の概要 ･･･････････････････････････････････････････････････････ a-29

1. 核融合科学研究所の研究活動に関する評価
評価者: A
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績1998 年以降 LHD 計画の功績には目を見張るものがあり，核融合エネルギー開発の成功に向けて解決されるべき主な課題を全て網羅している。同計画は，ヘリカルシステムに核融合エネルギー発生装置としての多大な可能性を生み出し，完全ではないにしろ，密度や圧力などにおいては効率的な核融合発電に必要とされるパラメーターを達成している。現在の課題はそれらを同時に達成することである。
さらに，より極端な運転領域の研究において，加熱源あるいは粒子／熱除去が原因の技術的制限によるもの
を除いては，根本的な物理的限界に達していないことを示した。また、これらの技術的性能についても向上が見込まれている。
私の意見では，LHD は核融合研究史において初めて，ヘリカルシステムが将来的に核融合エネルギー発電を担う重要な候補であることを，証明したと言える。同 LHD 装置は最新型トカマクシステムに類似した性質を持ちながら，強力なトロイダル電流に関連した難題（不安定性，ディスラプション，密度限界…等々）を抱えていな
い。
技術的観点から，１時間を越える定常プラズマ生成の可能性を証明したことは，より要求されるものに近い運転領域へと繋がり得る功績と言えるだろう。

b) （課題に順じた）専門研究
ディスラプションの無い，高密度運転領域の開拓は，近年核融合コミュニティが発展してきた中で，最も期待できる運転領域ではないだろうか。
<ß>値が 5%という核融合炉に相当する値に達したことは，繰り返すが躍進的進歩である。
と言うのも，磁場構造の実際の限界にはまだ達しておらず，明確な限界が見えないのは大変期待できる事実だと言える。

c) 将来計画得られた研究成果から，装置の加熱容量向上，閉ヘリカルダイバータの採用，および重水素実験は絶対的に必要だと思われる。
また，装置を物理的限界まで高めるのに必要な資源を見定めることに，全力を尽くされたい。
(2) シミュレーション科学プロジェクトa) 概要と功績
LHD に特化した閉じ込めシミュレーションおよびレーザー核融合シミュレーション分野をカバーした，大変意欲的なプロジェクトが提示され，既に有望な結果を残している。このグループが実験部門と密に連携し合っている
現状を，個人的には大いに支持したい。若手世代が同分野において積極的に活動しているのが見られ，非常に好ましい。

a-1b) （課題に順じた）専門研究
TJ-II のような，径電場に関して非常に詳細な計測を伴う他装置で得られたデータをシミュレーションデータに組み込むことは，今回提示された素晴らしい研究を更に拡張するだろう。
材料研究は将来の核融合装置にとって，ことさら重要である。
トカマク装置との比較も視野に入れておかれることをお薦めしたい。

c) 将来計画
今回提示された計画は意欲的であるが，同時に現実的でもある。
このタスクを成功させるには，最高水準の計算リソースを十分獲得するべきだろう。
(3) 連携研究a) 概要と功績本分野で積み重ねられた努力を賞賛したい。大型実験において，他のコミュニティから孤立するのが一般的な中，産業界や他の研究所，または核融合レーザーコミュニティや各種アウトリーチプログラムとの交流が進行中であるのを見るのは非常に喜ばしい。
特に，核融合用トリチウムに関する研究の強化を推進したい。ITER 稼動に近づきつつある今，これまで以上の問題解決を迫られており，本連携研究の努力は，これらの問題解決に大きく貢献してくれることだろう。首尾よく核融合エネルギーを導入するために，これは解決すべき重要課題である。
キッズ・エネルギー科学館設立に至る努力も高く評価したい。

b) 将来計画
ITER プロジェクト計画を視野に入れた現行の将来計画に，特別な注意を払っている。個人的には，ITER があらゆる世界的規模の核融合プログラムに強い影響力を持つことだろうと容易に伺えるため，成功への重要課題だろうと考える。
JAEA との密接な交流を推奨したい。
(4) 炉工学研究a) 概要と功績発表された研究課題は厳選されており，その成果は世界的に重要なものである。数多くの国際共同研究が実施されており，インパクトのある研究を行う上で強い自信に繋がっている。
論文数のような客観的指標を入れたことは，評価者にとっては大変役に立つ。

b) （課題に順じた）専門研究
長寿命溶融塩フリーベやリチウムブランケット研究は，目を見張るものである。ITER で試験する可能性が限ら

a-2

れているので，実際の環境でこれらのデザインを試す機会がどれくらいあるか，問題となるだろう。
中性子工学研究は，近づきつつある ITER 稼働（実験）に大変必要であり，歓迎される。
c) 将来計画発表された将来計画のために，十分な資源を調達することが重要である。
2. その他
この場をお借りして，近年 NIFS が達成してきた功績をお祝いしたい。優れた成果は，世界記録を更新する
LHD 実験結果のみに留まらず，科学研究において LHD を取り巻く全てのプログラム，国内外研究所との間で進行中の共同研究，各種技術プログラム，または，地道だが非常に重要な広報関連プログラム，これら全てに及ぶものである。
若手研究者や技術者が，すでに世界規模の成果を生み出していることは非常に頼もしく，素晴らしい。次期評
価では，このような高水準かつ世界的なリーダーシップをどのような方法で長期間維持していくか，その辺りに焦点を当ててみてはいかがか。
NIFS チーム全体として，本島所長の指揮下に得られた成果を，誇りに感じていただきたい。グループ全員に私の祝辞が届けられるよう祈りつつ，本島所長に心から賞賛の辞を申し述べたい。

a-3

評価者: B
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
核融合エネルギー研究は，これまで主にトカマク型装置を使用し，実施されてきた。
TRIAM-1M は既に LHCD を使用した定常運転を実証しているが，トカマク型では効率的な継続運転を達成することが難しい。この点から，ヘリカル型装置が極めて望ましい。しかしながら，LHD 実験の開始以前にヘリカル型核融合炉研究は殆ど行われていない。過去 6 年の間に LHD 実験研究が精力的に行われ，高温・高密度プラズマの達成に至った。特に 5%ベータ値の達成には感動させられた。
当初予測より高いパラメータに到達したことは，高く評価できる。

b) （課題に順じた）専門研究
1. 高イオン温度: 5.2 keV at n e = 1.6x10 19 m-3
2. 最大β=5.1%, 定常運転時(>100 τ e )は 4.5%
3. 最大密度: 1.2 x 1021 m-3
4. IDB（内部拡散障壁）の証明
さらに興味深い成果も数多く報告されている。

c) 将来計画
加熱機器の増強，閉ヘリカルダイバータ，および DD 実験の準備が進んでおり，今以上に優れた成果が期待される。 ヘリカルダイバータの設置が実験スケジュールに影響を及ぼさないよう，上手く調整されている。
ヘリカル炉設計は，LHD の実験成果を参照しながら進行しているように思われる。 結果が上手く反映された設計を期待したい。
(2) シミュレーション科学プロジェクトa) 概要と功績シミュレーション研究が精力的に進められていることは賞賛に値する。
高温プラズマ中では多様な現象が共存し，相関しあっている。よって，シミュレーション結果と実験結果が類似していたとしても，それが必ずしも実際のプラズマに該当するとは言えない。 この点を常に留意してほしい。

シミュレーショングループおよび計測グループは密な連携を取り合うべきだろう。

b) （課題に順じた）専門研究c) 将来計画

a-4

シミュレーショングループにおいて，ヘリカル炉シミュレーションの重点的取り組みが望ましい。
(3) 連携研究a) 概要と功績
数多くの業務に関して説明を受けたが，それらに関して，個々の最終目的を理解しづらかった。どのようなブーメラン効果が得られるのか示されておらず，現時点での評価は難しい。

b) 将来計画
ヘリカルダイバータ，DD 実験準備など，重要課題の選択が必要だろう。
最終目的も提示されるべきである。
(4) 炉工学研究a) 概要と功績
ブランケット，中性子，マグネット等々に関して説明されたが，期待される炉のパラメータ（寸法，磁場強度，
プラズマの規模）が示されていない。開発中とされている炉のスケールが公開されていれば，これまでに達成された段階も評価しやすいと思われる。

b) （課題に順じた）専門研究
超伝導の開発結果に強い関心がある。高く評価できる成果を上げた。

c) 将来計画
ヘリカル炉計画が期待される。ヘリカル炉／トカマク炉の長所・短所について，両者の比較研究が望まれる。
また，それぞれの規模を示してほしい。
エネルギー問題を考慮すれば，規模や予算の問題はさて置き，まずは実現化が最重要視されるべきだろう。
2. その他
過去数年間で組織が改良され，研究所は数多くの傑出した功績を生み出してきた。特に LHD 実験の優れた成果に関しては，世界的評価に値する。
本島所長および研究所スタッフを賞賛したい。

a-5評価者: C
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
大型ヘリカル装置 LHD プロジェクトは，1986 年，わが国のプラズマ・核融合研究者の間での純学問的討論に基づいて，大学関係がその総力を結集して取り組むべき次期大型研究計画として採択されたものである。採択に当っては，外部導体系ヘリカル磁場閉じ込め方式が，少ない還流エネルギーによる定常運転，高温・高ベータプラズマの長時間保持の可能性を持つことに留意し，当面 LHD が，内部電流系トカマク型装置を含む環
状磁場閉じ込め方式におけるプラズマ物理の総合的理解へ寄与するという期待が込められた。具体的研究計
画としては，①多様な磁場配位による高ｎτT プラズマ閉じ込めの最適化，②高ベータ領域での圧力駆動不安定性などの物理と閉じ込めへの影響の解明，③長時間運転による不純物制御，燃料給排気などの基礎資料の提供，④ヘリカルリップル磁場のもとでの高エネルギー粒子閉じ込め特性の研究，⑤核反応シミュレーション研究，などが挙げられた。
LHD は，1998 年 3 月，最初の着火以来，10 年間の間に，上記研究目標にしたがって着実に研究を進め，ほぼ所期の目的通りの成果を挙げ，世界の炉心プラズマ磁場閉じ込め研究において，ユニークな価値ある研究貢献を果たして来たと高く評価する。特に，高ベータプラズマの長時間保持を実現し，その MHD 特性，輸送，周辺制御などの面で，重要な基礎的な資料を提供したこと，また，ペレット入射による中心部ピーク高密度を維持する内部輸送障壁の発見など，核融合炉心を展望する環状磁場閉じ込め方式の総合的理解に大きな貢献を果たしてきた。

b) （課題に順じた）専門研究
・

閉じ込め最適化について
磁気軸の位置，アスペクト比などを変化させて，MHD 特性，加熱効率，輸送の観点から，高ベータプラズマの閉じ込めの最適化をはかり，最大＜β＞＝5.1％を達成し，＜β＞＝4.8％でエネルギー閉じ込め時間の 85
倍の定常運転を実現した。また，圧力駆動不安定性や周辺磁気面の破壊に伴う MHD 平衡・安定性・輸送への影響を系統的に探求すると共に，垂直入射中性粒子ビームによる加熱を実現し，その閉じ込め特性を調べた。これらの成果は，環状磁場閉じ込めプラズマ物理の立場からも，また，炉を展望する観点からも，極めて優れた貢献であると判断する。
・

内部拡散障壁(IDB)について
中心部への連続的ペレット入射の際，内部拡散障壁（IDB）形成による中心部ピーク高密度・高圧配位の生成・維持が，従来局所アイランド・ダイバーター配位で見出されていたが，磁気軸の外側シフトなどにより，通常のヘリカルダインバーター配位でも実現可能なことを見出し，その稼動領域(磁気軸・β)を同定した。これは，ヘリカル系における炉心プラズマ生成保持を展望する立場からも，重要な一歩であると判断する。実験結果によると，電子密度勾配が急峻なところでも，電子温度勾配はなだらかなままである。今後，IDB 形成に関わる拡散係数の物理機構の解明および CDC などの不安定性の同定と制御などに関して，理論・シミュレーションと協力した詳細な研究が期待される。
・周辺プラズマ制御
ベータ値の上昇に伴う周辺磁気面の乱れの効果の制御は，ヘリカル系プラズマ保持の定常化を図る上で，避けて通れない課題である。＜β＞～4.8%までの領域で，閉じ込め劣化が見られなかったことは，重要な成果である。また，高イオン温度下での不純物ホールの生成，高密度での衝突摩擦による不純物遮蔽，エルゴディ
ック層の影響についての様々な解析，closed helical diverter 配位の設計など，多彩な研究が行われており，粒子・熱流束の周辺制御に見通しをつける研究として，今後の更なる進展が期待される。

a-6c) 将来計画
最も望まれる将来計画は，重水素の導入である。地元の了解という難しい問題が絡んでいることは理解できるが，ここまで当初の計画が進行してきたことを考えると，重水素を用いた閉じ込め特性，特にイオンや不純物粒
子の閉じ込め比例則への同位体効果などの研究，更に進んで，少量のHe3を混入して，そのICRFマイノリティ
加熱による核反応シミュレーション研究にまで発展することを期待したい。
ただし，現在の LHD 装置の大幅改造や，新たな大型ヘリカル装置の建設については，現段階では，時期尚早であると判断する。当面は，現在の LHD（加熱増力，ダイバーター配位の改造等の適度の増力・改造を含む）を活用した更なる研究の進展を図ることとし，次期計画については，ITER や ICF 関係の成果を見定めつ
つ，核融合研究全体の立場から，慎重に判断するべきであろうと考える。
(2) シミュレーション科学プロジェクトa) 概要と功績
まず第 1 に，シミュレーション研究グループが大きな研究グループとして成長したことを高く評価したい。そして，①LHD and Magnetic Confinement Simulation Project ②Laser Fusion Simulation Project③Plasma Complexity Simulation Project の三つのプロジェクトを同時に進行させることが出来るに至ったことを喜びたい。
この中で，中心となるプロジェクトは，①LHD and Magnetic Confinement Simulation Project である。このプロ
ジェクトの中に，炉心プラズマについて，２流体モデルによる研究グループと，運動論的モデルによる研究グル
ープ，そして周辺プラズマ研究の三つのサブグループが，それぞれ，２流体モデル，ジャイロキネティックモデ
ル，及び境界のモデル化で，着実に研究成果を挙げている。そして，これら三つのサブグループの研究成果の統合により，多階層シミュレーションモデルを構築し，Numerical Test Reactor Project を推進しようとしているのは，適切な方策であると考える。同時に，この研究プロジェクトが，様々な分野における多階層現象に関する
シミュレーション研究の魁としての役割を果たすことを期待したい。

b) （課題に順じた）専門研究
特筆すべき成果を挙げているのは，gyrokinetic Vlasov model を用いたヘリカル系での ITG 乱流と zonal flow
に関する研究である。ITG 乱流とその zonal flow の形成による安定化については，軸対称トカマクでは既に多くの研究が行われ，非軸対称ヘリカル系でも，核融合科学研究所にあった小型ヘリカル装置 CHS において，zonal flow とその乱流抑制効果が実験的に確認されているが，ヘリカル系でのシミュレーション研究による詳細な解析は初めてであると思われる。非軸対称性に伴う径方向電場の効果も取り入れての解析であり，新古典
リップル拡散を最小化する磁場配位で，zonal flow による乱流拡散抑制が強く働き，乱流拡散も抑えられることを明らかにした。径方向電場がどのような形に取り入れられているのか不明なところがあるが，粒子拡散束の非両極性により生成される電場をセルフコンシステントに取り入れた解析が望まれる。

c) 将来計画
シミュレーション研究では，モデル化とシミュレーション解析手法が鍵となっている。これらは，特定の対象(ヘリカル系プラズマ)に限定されるものではなく，様々な複雑系の解析に応用できるものである。現に，従来の理論・シミュレーション研究センターでの中心課題であった開放系での自己組織化に関する研究は，その後幅広い他分野への応用へと発展しており，自然界の複雑系研究手法に新しいパラダイムを切り開いてきたといえる。
多階層現象の統合的研究は，地球規模での気象現象や大気・海流等の研究，地球内部構造や地殻変動の研究，生命科学，宇宙科学等々の分野で，避けて通れない課題となっている。自然科学研究機構内の他の研究所を含む関連研究機関との意欲的な共同研究により，シミュレーション研究グループが，このような幅広い研

a-7

究分野を包括する新しいシミュレーション研究の潮流を導く魁としての役割を果たされることを，将来に期待したい。
(3) 連携研究a) 概要と功績
連携研究センターが，限られたメンバーで，国際協力，ITER 関連研究連携，レーザー関連研究連携，原子・分子・周辺プラズマデータ収集・解析，産業連携，核融合子供科学館など多彩な活動を展開していることは評価に値する。
核融合科学という観点からは，従来，どちらかといえば，スピンオフ中心の活動であったのが，核融合炉を志向した活動に重点を移してきているのは，望ましいことである。

b) 将来計画
ヘリカル系と並んで，現状で核融合炉に最も早くつながると思われているトカマク(ITER，球状トカマク)や，
ICF(FIREX)に関する連携研究に一層の力点がおかれることを期待する。これらの中には，核融合科学研究所の将来計画にも関わってくるものがあると思われるので，全国の核融合関連研究者の間での将来計画に関する学問的立場からの討論を，全国共同利用体制を活用して，喚起し・組織して行くことを勧めたい。
(4) 炉工学研究a) 概要と功績
専門外でもあり，特に意見はありません。

b) （課題に順じた）専門研究および将来計画
専門外でもあり，特に意見はありません。

c) 将来計画
専門外でもあり，特に意見はありません。
2. その他
本島所長の卓越したリーダーシップのもと，思いきった組織の再編を行い，研究所の中核をなす LHD プロジ
ェクトを着実に推進し，あわせて，高温プラズマという複雑系のシミュレーション研究を大幅に拡張，進展させてきていることに，深い感銘を受けた。また，これらの研究を通じて，優秀な若手研究者が続々育成されてきている姿に，心を奪われると共に，頼もしく感じた。
今後，この成果を基盤にして，次期所長のもとに，更なる研究の発展と，斬新な展開が行われることを期待したい。なかでも，母屋である自然科学研究機構の他の研究機関との連携による新たな学問的発展が芽生えて来ることを期待したい。

a-8評価者: D
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
LHD 装置は核融合工学における代表作である。
LHD 性能の利点を余すところなく活かし，過去６年間で重要な目標を達成し、成果を納めてきた。大きな発見の主要なものとして，不純物ホールなどの有用な現象をともなう高イオン温度，オープンヘリカルダイバータ配位における内部拡散障壁を伴う高密度運転，5.1％という極めて高い平均ベータ値，また 54 分に及ぶ定常運
転，等があげられる。これらの成果によって核融合炉の温度に到達し，また，ベータ値やプラズマ密度，および入力エネルギーにおいても世界記録を樹立した。これらの素晴らしい成果は，LHD に従事する全チームおよび各研究者が現行のリーダーシップによって纏められて，総合的かつ団結した貢献を成し得た結果である。さらに，核融合の最終目標に向けて性能を益々向上させるよう，科学技術の基礎が築かれてきている。

b) （課題に順じた）専門研究
厳しい核融合要件にを満たす三重積に近付く密度・温度・および閉じ込め時間を同時に達成するため，LHD
性能を更に向上させるには，NBI，ICRH，ECRHから構成されている加熱能力の増強，閉ダイバータ配位の適切な導入，および重水素運転が採用されるべきだろう。また，定常運転に関しても，核融合炉に求められるデータベースを拡大することに取り組むべきである。高ベータは，シャフラノフシフトを注意深くリアルタイム制御したりR ax 制御することで，さらに上昇させ得る。閉ダイバータ配位は，周辺部の閉じ込めを改善する可能性があり，よって，ベータ値の上昇に伴う閉じ込め性能の低下を軽減すると思われる。また，改良されたペレット入射シ
ステムと閉じた磁場配位の相乗効果により，プラズマパラメータが更に向上すると思われる。さらに，全般的な運動量輸送の研究，特に不純物輸送との相関に注目していただきたい。不純物ホールの発生には，細密な考察と更なる進展が求められる。

c) 将来計画
直近の将来計画は明確に定められており，適切に予算措置がなされている。物理プログラムは，現在利用可
能または近い将来運転が見込まれている幅広い計測により十分にサポートされている。しかしながら，NIFS の
現在の戦略に沿った，より積極的な目標が強く求められる。不可能と思われるほどのプラズマパラメータを達成
している現在の研究の勢いを，絶対に維持してほしい。故に，大きな目標を掲げた統合的アプローチの採用が不可欠である。プラズマパラメータ向上のため，NIFS の秀逸な工学と計算技術に基づく斬新で繊細な方法を模索されたい。小規模装置で近年達成した成果（例：Li 運転）に関しては，より核融合に近い条件の LHD を用いて試験し，利用すべきだろう。
(2) シミュレーション科学プロジェクトa) 概要と功績現在に至るまで，LHD 実験の適用性および予測性の向上という点で，目を見張る発展が遂げられた。これは主に，LHD の意思決定，および優れた実験結果という魅力に理論を統合させた結果である。各研究系は現在
LHD の核融合性能に着目しており，実験期間中に達成した主な功績を支えている。しかしながら，シミュレー
ション科学は斬新で傑出した LHD 性能の向上に向けた様々な独自提案を出していくことで，その意義を更に高めていく必要がある。核融合の展望を更に広げるため，極めて多岐にわたる複雑なコードが開発された。
LHD 実験の新たな流れは，シミュレーション科学研究部によって充分に注目されている。レーザー核融合シミュレーションプロジェクトやプラズマ-材料相互作用の数値的研究によって，益々共同研究の効果が広まること

a-9だろう。シミュレーションプロジェクトは，理論核融合研究に携わる国内の数多くの大学と連携し，研究を行っている。これらの活動は，NIFS の幅広い業績に益々求められるだろう人材を提供するためにも，シミュレーション
科学研究部が特に注力すべき課題だろう。

b) （課題に順じた）専門研究
LHD 関連研究を含んだ目標は的確に定義されている。しかしながら，これらは大変重要な項目として CDC，
IDB，そして不純物ホールなどの最新かつ話題の課題を含んでいるべきである。シミュレーション科学研究部
は，これらの実験の進展を理解し，その成果をより発展させる上で主役を担えるよう，あらゆる手段を用いて尽力してほしい。さらに，モデルは自己矛盾のない可能な限り最高レベルのものとなるよう目指すべきである。この目的を達成する上で，熱核融合研究のために日本で稼動する新計算機の稼働にあたって充分配慮されるべきである。シミュレーション科学研究部の出版歴は素晴らしい。自己組織化，リコネクション，ホリズムプロジェ
クトと言った，一般科学に関わる重要課題は，適切に取り組まれている。 これらは NINS インフラへの統合という点で非常に重要である。

c) 将来計画
数値試験炉プロジェクトは非常に積極的で賞賛に値する。ITER モデリンググループとの実り多い研究協力や支援はさらに強化されたい。LHD 実験結果の理解や意思決定への統合を継続し，さらに追及すべきだろう。
SSP が取り組んでいる広範囲の課題を維持する必要がある。
日本に存在する大型計算機基盤を使い，計算パワーの拡大を図る研究を実施してもらいたい。 NIFS と連携している多くの大学が有する理論知識やスキルの蓄積は，シミュレーション科学研究部の効果拡大に利用できるだろう。LHD 重水素実験の利点に注目したシナリオに取り組む必要があるだろう。
(3) 連携研究a) 概要と功績
連携研究推進センターでは傑出した活動が行われ，LHD の経験から得た知識の産業科学各分野への波及効
果を高めている。同センターは DEMO 計画にとって重要なトリチウムインベントリーと言った将来的課題を提示することで，核融合研究の新領域を拡大している。また，PWI や原子データに関する問題を解決することにより，現行および将来の LHD 実験に貢献している。ITER 関連研究にも大きな進展が見られる。レーザー核融合研究や国立天文台との共同研究は，非常に高く評価できる。NIFS キッズ・エネルギー科学館に始まるアウトリーチ活動は非常に好感が持てる。
連携研究推進センターはよく整備された組織であり，NIFS インフラにおける強力なツールである。
PWI 活動は目覚しい発展を遂げ，既に将来の LHD および QUEST オペレーションに貢献する用意が整っている。移動表面式プラズマ対向機器（MS-PFC）などのオリジナル概念は，固体・液体双方とも先ずは QUEST で試験した上，成功したならば LHD での試験が必須である。現代の原子物理学進歩に基づくプラズマ計測方法
を，LHD および太陽観測衛星「ひので」に導入するべきである。他の研究資源からの情報不足という点を鑑みれば，トリチウム研究にもより重点を置くべきである。産業応用に重要な，マイクロ波加熱による製鋼技術を用いた研究開発を，優先的に考えるべきである。ITER 用ミラーの製造も，連携研究推進センターが提示した重要テーマである。

b) 将来計画
連携研究推進センターはセンターの活動を向上させ，LHD 計画への更なる統合を図っている。ITER およびBA との協力関係を強化，発展させることが不可欠である。IFMIF（国際核融合材料照射施設）の不確実性を考慮した上で，トリチウム処理に関する研究は，ことさら重要視されるべきだろう。アウトリーチ研究を他の専門家
集団や民間グループに拡大してみてもいいだろう。JT60-SA 用超伝導コンダクターの試験は絶対必要である。

a-10

DEMO 関連問題に関する新たな研究は，率先して行うべきだと思われる。人材に限りがあることを考慮すると，国内大学がもたらし得る貢献という観点から，NIFS および NINS 活動内での研究協力は不可欠である。
(4) 炉工学研究a) 概要と功績
炉工学研究センターは，比較的新しい活動に代表され，核融合工学の問題に深く取り組んでいる。同センター
は，既に重要な情報を提示しており，核融合炉が直面するだろう最も重要な課題を指摘した。フリーベやリチウ
ムに基づくブランケットの問題に取り組んでいる。V（バナジウム）合金やフェライト鉄の溶着，照射，腐食，またはコーティングに関する試験が実施された。炉のニュートロニクス（中性子工学）研究用に，高速フィードバック
3D コードシステムが開発途上である。適用性に限界はあるだろうが，14MeV モックアップ試験が実施されている。

b) （課題に順じた）専門研究
炉工学研究センターの専門研究は，ブランケット材料システム，ニュートロニクス，およびマグネット材料システ
ムで構成されている。バナジウム合金の溶着に関しては，酸素不純物除去により，既に可能性が示唆された。
高純度金属バナジウムがV合金高熱負荷に対して開発された。NIFS-HEAT-2 は，不純物混入を防ぐため，高純度Arフローで溶接された。溶接材料において破壊エネルギー減少が進んだが，照射後焼鈍によって回復した。溶接クオリティの低下は中性子照射 8.5dpaで現れた。溶融塩フリーベや液体リチウムの強制対流ループに関する設計や実現性研究が進んだ。高度コーティング技術やトリチウム浸透バリアの発生を実証してきた。高速フィードバックシステムがニュートロニクス設計に統合された。十分な遮蔽下でのトリチウム増殖に成功した。
14MeVニュートロン照射後，多様なNb化合物の臨界電流が調査された。V 3 Gaの電子電流を向上させるため，
低活性化型超伝導ワイヤが使用されたc) 将来計画
周辺構造の非対称・フラクタル配置に関して，中国ASIPPと共同で取り組む予定である。14MeV照射中および後のその場観測の実施を予定している。ITER TFマグネット製造を円滑化させるため，全Nb 3 Sn素線に関して試験を予定している。東北大学大洗センターとの間で実施予定の 15.5Ｔおよび 500A電流リードに関する共同研究に重点を置かれたい。炉工学研究センターは，超長時間スケールでの熱クリープを調査するための長期クリープ試験を継続すべきである。核分裂での経験やノウハウを参照しながら，DEMO炉に関わる他の選択肢を追求・発見していくことが不可欠である。
2. その他
現所長は核融合研究の最先端で，NIFS の世界的リーダーとしての地位を築き上げた。
この成果は幅広い研究活動の完全なる調和，そして，これらの活動を熱核融合炉という共通課題に統合したことにより，達成されたものである。現所長の指揮下で達成された今の勢いを維持するため，詳細な計画を考えていく必要がある。

a-11

評価者: E
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
LHD は，世界中のステラレータ実験研究の最重要装置であり続けている。同時ではないにしろ，LHD はプラズ
マパラメータの新たな記録を達成しており，これらは MHD 不安定性による過度な劣化の見られない超高ベータ（磁場強度を 20%に減少時），ペレット入射による超高密度，核融合条件に匹敵するイオン温度，および中心部不純物の蓄積軽減を伴う興味深い新領域などにより，実証された。このように LHD は，ヘリカルプラズマ閉じ
込めの物理的理解に貢献し続けている。これはまた，国際的な核融合プロジェクト ITER に，特に周辺磁場のストキャスティック化およびトロイダル磁場制御による MHD 安定化において，深く関連している。
JT-60SA が定期運転を開始するまでは，LHD は日本の最重要核融合装置であり続けるだろう。よってその時まで，核融合実験研究の国内活動は，自ずと LHD に集中し，ステラレータとトカマク研究の間での重要な相互発展を生み出すだろう。

b) （課題に順じた）専門研究
LHD は，当初の予測を上回る性能を示している。これは偉大な功績であり，核融合エネルギーに向けたステラ
レータ概念の信頼度に大きく寄与するものである。（磁気軸の移動およびプラズマアスペクト比の変更により）最適化された磁気閉じ込めのみに留まらず，NBI（現在 23MW，7MW の追加を計画中）に代表される加熱パワーの体系的拡充にも支えられた結果，傑出したプラズマ性能が達成された。高速ペレット入射と相まって，急なエッジ勾配で超高密度運転を可能にする新たな運転領域が発見された。さらには，エルゴディック層での遮蔽効
果によって，不純物蓄積が妨げられるという，興味深い運転領域も見出された。これにより，超高密度・高圧，
および（低磁場状態で）高ベータプラズマが首尾よく生成され，維持できている。高ベータ時の MHD 平衡および安定性の問題について，LHD チームは極めて成功裏に取り組んだ。
上記のことから，LHD が目標値の達成に向かっていることは明らかである。加えて予想外の発見にも恵まれ，高レベルな基礎研究（特に MHD 不安定性，アルヴェンモード，ゾーナルフロー等）を実施している。秀でた
LHD 研究の更なる追求に向けて，いくつか提案するので検討していただきたい。
•

•

•

•

発見された新たな運転領域の物理的理解を急ぐべきである。IDB，CDC，および不純物ホールは大変有望で，大いに意義のある発見である。ここにおいて，理論，計算機シミュレーション，特化した実験を組み合わせた体系的アプローチが有用だろうと思われる。
高密度領域における電子・イオン温度は比較的低い（概ね 1keV前後）。逆に，目標温度は必要な値より一桁低い密度で達成されている。LHD装置の柔軟性を活かし，最適なn·T i ·τ E を達成するため統合シ
ナリオを策定されたい。
ハイパワープラズマの定常運転は，更なる安定性向上のほか，核融合研究におけるステラレータ概念の魅力である。閉ダイバータの詳しい設計および建設を可能な限り急ぐべきである。定常加熱パワーの4MW への改善が計画されており，閉ダイバータの完全導入とともに，実現されたい。
核融合炉研究は，トカマクに基づく現行の DEMO 研究と密接に結びつくべきである。そしてそれらの長所、短所が明確に示されるべきである。ステラレータに関しては，グリーンワルド限界が無いことによって，より高密度・低温での燃焼への展望が開かれたことは明白である。これらの炉条件下における熱不安定性，中性粒子輸送，不純物生成および輸送のもつ役割について，全貌が分かればより有益だろう。つまり，「数値試験炉」（以下参照）が非常に重要な役割を担うことになる。

c) 将来計画

a-12

重水素プログラムの実施により，同位体効果を探求する計画は，高く評価される。これは LHD の性能向上にも繋がるだろう。装置の更なる開発に関しては，主に，(I) NBI（32MW へ）および ICRH（4MW へ）の増強，(II)閉ヘリカルダイバータの開発，製作，および組立が考えられる。 後者に関しては，段階的アプローチが計画されており，長期的な実験休止を防ぐ意味合いでも，合理的だと思われる。
推奨：•

閉ダイバータの詳細設計の公開と同時に，国際専門家（特に工学分野）を交えた詳しい設計評価の実施が望ましい。
• MHD データベースの確立は高い賞賛に値する。これらの活動を正式な国際協力協定に盛り込むことも，有益であろう。
(2) シミュレーション科学プロジェクトa) 概要と功績
実験側に立つ研究者の視点から見た場合，シミュレーション科学プロジェクトには高く評価される科学研究があり，国際的競争力を持つと思われる。上記で述べたとおり，LHD で新たに発見された運転レジームを理解するために，集中した取り組みが求められる。NIFS シミュレーション科学プロジェクトは，これら課題の取り組みに向けて，合理的に配置されているように見受けられる。MHD や LHD シミュレーションからレーザープラズマ，複雑性プラズマまでに至る NIFS シミュレーション科学プログラムの奥行きを拝見できて光栄に思う。この学際的アプ
ローチは明らかに NINS の方針であり，機構研究所間の連携協力を育成している。
b) （課題に順じた）専門研究
特になしc) 将来計画
例えば，乱流やゾーナルフロー分野などにおけるコードを更に発展させていく上で，高性能コンピュータへのアクセスは極めて重要である。新たなスーパーコンピュータおよび NIFS プラズマシミュレータ計画は，高く支持できる。
(3) 連携研究a) 概要と功績
NIFS は，日本の大学環境に非常に上手く溶け込んでおり，それが高い相互利益を生むことは明白である。特に PWI，材料科学，原子物理学，計測，および基礎プラズマ研究などの場合が挙げられる。一方で，連携研究推進センターは，大学施設が LHD プログラムに適切に統合されていることも確認しており，これは言うまでもな
く素晴らしい功績である。

b) 将来計画
ITER および DEMO 活動との密接な関わりは，ステラレータコミュニティにとって絶対的不可欠であり，連携研究推進センターが進もうとする方向性は，極めて正しい。
(4) 炉工学研究a) 概要と功績

a-13

LHD の工学的観点に関しては，(1)で既に記述済みである。
b) （課題に順じた）専門研究
特になしc) 将来計画
特になし
2. その他
本特別評価会合は，私がこれまで参加した中で，最高の評価会合であった。本島教授が所長任期中に積み上げられた，NIFS の傑出した成果の数々について，最も端的に述べられていたと思う。彼の成功は高く評価され，また，賞賛されるべきものである。また，高い見識を持ち，周囲の尊敬を集める小森教授が次期所長を務めると伺って，心から喜ばしい気持ちである。小森教授の成功とともに，次の評価会合に参加するのが待ち遠しい。
会議中の口頭発表も大変素晴らしかった。取り分け，若手世代によるプレゼンテーションにおいて，榊原博士（高ベータ運転），坂本博士（高密度運転），渡邉博士（ゾーナルフロー）の発表の質の高さに驚かされた。
NIFS 所属のこれら若手研究者が，国際会議で招待講演者として登場する姿をいつの日か拝見してみたいも
のである。

a-14

評価者: F
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
LHD は巨大核融合実験であり，高温プラズマや核融合物理の発展に大きく貢献した。また，特にステラレー
タ・ヘリオトロン物理理解への寄与は計り知れない。主な技術的成果は，複雑な超伝導装置の安定した運転に拠るところが大きい。ここで，磁場の更なる増強について特に注目しておきたい。また，定常プラズマ運転の実証は，今後の発展を考慮する上で非常に有意義である。大変貴重な科学的成果として，改良された閉じ込め特性を使った高密度運転の実証，5%という驚異的な数値に達した高ベータ運転，および低不純物含量（いわゆる不純物ホール）でのプラズマシナリオ，などが挙げられる。

b) （課題に順じた）専門研究
高密度運転： 核融合炉でハイパワー密度を達成しようとする場合，高プラズマ密度が必要不可欠になる。内部拡散バリアは，ステラレータ／ヘリオトロンで非常に高い密度が達成でき，閉じ込めの同時改良が可能である，という２点を実証している。加熱パワーの増加が見込めれば，更なる密度向上も可能だとする結果は大変興味深い。
高ベータ運転： 高ベータもまた，ステラレータ／ヘリオトロン炉に求められる。5%の体積平均ベータ値が認識されており，これは LHD により達成された値である。さらに，ベータ限界（beta-limiting）MHD 不安定性について，より向上した理論的理解を言及されたい。特に，LHD プラズマの MHD 安定性に関する理論的予測があまり良くなかった状況に反して，この方向について更なる研究が奨励されるべきである。この観点から，磁場トポロ
ジーと MHD 安定性（つまり安定性と平衡点上限）の関連性を研究するのに採用されたアプローチを更に追及されたい。
不純物輸送： 不純物の蓄積は，ステラレータ研究が重要課題とするものの一つである。LHD は，少なくともある一定の条件下において，不純物蓄積を回避できることを示した。多彩なプラズマシナリオ（高密度，低密度，
高ベータ，様々な境界プラズマ条件，等々）を含む同方面の研究推進を大いに期待したい。
計測： 計測に関しては特に言及されなかったが，敢えて，発表された実験データの秀逸さを書き添えておきたい。なお，これらはプラズマ実験を解析・理解する上で，前提となるものである。
全体として，これらの成果は顕著な発展がなされ，また，LHD が国際核融合研究を率いている事実を明示している。また，高プラズマ性能の達成以外にも，実験・理論グループ間の協力強化に基づく優れた解析力が注目されてきた。これについても更なる強化が望まれる。さらに，今後の研究においては高プラズマ性能の発展に向けて，より統合的アプローチを目指されたい。

c) 将来計画
加熱システム増強とダイバータ：
加熱システム増強，およびアクティブクーリングされたダイバータを採用する計画は，非常に肯定的に受け取られてきた。特に，開発に関して先に述べたコメント「好ましいプラズマ特性を組み合わせたプラズマシナリオ」に関して，これは大変重要なステップである。特に高密度状態での上限をなくし，また，運転領域をより高磁場での高ベータに拡大するためには，加熱パワーの増強が求められる。これは，より大きいパワーの処理が可能な
プラズマ排気を示唆している。アクティブクーリングは高パワー定常運転の実現に必要である。シャットダウン期間の最小化を目指し，モジュラ方式でダイバータを拡張するというアプローチは十分支持されるものである。

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(2) シミュレーション科学プロジェクトa) 概要と功績理論とプラズマシミュレーションは，核融合実験で見られる複雑現象を理解する上で，必要不可欠である。ここで，NIFS は共同研究者と連携し，たくさんのツールを開発した上に，第一原理に基づく理論において目覚しい発展を遂げた。これには MHD 不安定性，およびプラズマ中心から境界に渡るプラズマ輸送が含まれる。また，関連各分野との繋がりにも注目したい。シミュレーション科学は，大学グループと密な連携を取り合う上で，非常に適した条件を提供しうる分野である。これらグループの協力参加が上手く機能している。

b) （課題に順じた）専門研究
乱流輸送，MHD 安定性，リコネクション現象，PWI といった，核融合研究における重要課題を含む，多数の研究トピックが発表された。個別発表では乱流輸送が取り上げられ，LHD の内寄せ配位が優れた新古典的閉じ
込めだけに拠らず，乱流輸送の軽減によっても，閉じ込めを向上させたことを説明した。この研究は実験結果を説明するというだけでなく，乱流と新古典的輸送の関係という重要課題を取り上げている点で，非常に貴重である。

c) 将来計画
LHD・磁場閉じ込めシミュレーションプロジェクト，および数値試験炉計画は，既存実験および核融合炉の基本
特性への理解を深める上で，重要なステップである。発表された計画を強く支持したい。より発見的なシミュレーションと，第一原理に基づく理論の均整が上手く保たれている。今後に関しては，不純物輸送・MHD 安定性といった分野の実験と理論間の連携強化を推進することを推奨したい。
(3) 連携研究a) 概要と功績
核融合には，安定した長期的研究と開発が求められる。このことから，教育および科学技術研究への参加，双方に関して大学の統合化が貴重になる。数々のトピックを網羅した大変な数の共同研究計画が発表された。多様な専門トピックや研究グループの中心として，NIFS や LHD を利用するというアプローチ方法は，大学や他の研究グループの参画を仰ぐ上で適切な戦略である。

b) 将来計画
NIFS の直接的・間接的関与を問わず，大学の ITER および DEMO 開発への関与を含む将来計画が強く求められる。
このような大型施設および開発プログラムには，若手研究者やエンジニアの人材開発のみならず，市民の理解を得る上でも，幅広い学術的基盤が必要になる。
この観点から言えば，若年層により核融合研究関連トピックが紹介されている現状は，非常に素晴らしい。
(4) 炉工学研究a) 概要と功績
DEMO に関して非常に積極的な開発計画が発表された。紹介された技術関連トピックは，開発が必要とされる
主な分野を網羅している： ブランケット材料システム，ニュートロニクス，マグネット材料システム。個々の要素の統合を可能な限り試験するシステムを構築する計画が，強力にサポートされている。将来的なことになるが，

a-16

開発計画について，意思決定要件を含めどの程度 ITER および IMFIF スケジュールに依存すべきか，より詳細な解析が有用になるだろう。

b) （課題に順じた）専門研究および将来計画
ブランケット材料システム： ブランケット技術の解決策となり得る興味深い新成果が発表された。発表は，液体増殖ブランケットの開発に特定して行われた。素晴らしい発表に加え，同研究分野が，優れた共同研究，および健全な原子力産業界の恩恵を大いに受けているように感じられた。今後に関しては，水素回収の整合性に関するフィージビリティスタディや，フローシステムにおける熱交換といった分野でのシステム統合が計画されており，これは強力に支持できる。将来的にはこれらのブランケットを ITER で試験できるよう，同計画をより精密に練り上げることを推奨したい。
ニュートロニクス： FFHR の設計は，トリチウム増殖および中性子遮蔽用３次元中性子計算に基づいている。これらの計算は，DT 中性子照射計測によって検証されており，非常に頼もしい。将来計画には，複雑配置および更なる検証できる計測に対応する改良中性子計算が含まれる。
マグネット材料システム： 中性子照射によるマグネット性能（臨界磁場）への影響について，多様な超伝導体に関して詳しく議論された。今後の研究に高温超伝導体が含まれているが，これは低温システムの要件を大幅に軽減させるため，強く望まれている。
2. その他最後になるが，今回評価委員に加えていただけたことを心から感謝したい。NIFS や LHD について多くを学んだばかりでなく，ハイレベルな研究発表や，正しい根拠に基づく討論を非常に楽しませていただいた。本評価に参加している若手研究者は，NIFS が将来に向けて準備万端であることを実証した。是非，これら若手研究者の主要会議出席を奨励していただきたい。

a-17評価者: G
１． はじめに
核融合科学研究所（以下NIFS）の設立に当たって、そこで行われるべき主計画について論議するために、
学術審議会核融合部会の下に国内の主要な研究者によって構成される作業部会が置かれ、学術的立場から徹底的な論議が行われた。
その結論として、世界的にも最も多くの研究者が研究に携わり、その時点において学術的知見の最も豊富な環状系プラズマを取り上げ、その中でも磁場の配位設定の自由度の高い外部導体系を取り上げることとし、トカマクを含む環状プラズマの閉じ込めの物理の研究を行うこととした。
NIFS における大型ヘリカル系の研究は、先ず超伝導マグネット技術を含む装置技術開発に始まり、装置建設とそれらの成果を踏まえて順調に装置の建設が進行し、広い視野で見据えた所期の設計・建設が順調に進
み、世界を代表する大型環状装置として優れた研究成果を挙げている状況は、初期の期待に沿うものであって、当初からその研究の進行を期待の下に見守ってきた一人として、今回の報告は、期待を裏切ることのな
い、極めて満足すべきものであったことを先ず申し述べたい。
２． 大型ヘリカル装置研究について
共同利用研究所であるNIFSにおける主計画として、適切な計画の下に、高イオン温度(5.2keV)、高密度(1.2×1021m-3)、高β(5.1%)の定常運転の記録は特記すべき優れた成果と考えられる。更に、記録として良好なデータを追求すると言うのでなく、上にも述べたように、環状系の閉じ込めの特性を詳細に研究するという当初与えられた使命を十分に考慮した活動の成果としてこのような良いデータを得たことは大いに称揚されるに値する。
３． 共同利用研究機関としての活動について① シミュレーション科学
上に述べた主計画の遂行においても、共同利用機関としての機能を果たすことはいうまでもなく重要である
が、それのみでなく、核融合分野全体への寄与が求められるのは当然である。先ず最近の計算機科学の、ハードウェアとソフトウェアの急速な進歩の恩恵を十分に活用するためのシミュレーション科学は核融合研究の重要な研究手段であると共に、それと深い関係を持つ広大な領域と交流することによってその進歩を図ることは、
共同利用研究所の重要な使命である。
特にシミュレーションは、巨大科学としての核融合研究においては、主計画における実験的研究の成果を理解し、その将来を予測するのみでなく、その閉じ込め特性を解析する事によって、トカマクなど、他の配位による閉じ込めにその成果を活かす手段としても重要である。
またその成果は単に計算機ハードウェアの性能や一般的なソフトウェア技術だけでなく、核融合プラズマ固有の特性を考慮した上で開発されるシミュレーション手法の開発が極めて重要であり、その面での能力が要求される。
NIFS における理論・シミュレーション科学の評価は極めて高いものがあり、今回の成果にも、我々の当初の期待を十分に満たすものであった。

② 連携研究核融合科学のように、大規模な予算を必要とする研究には、その主たる計画の遂行と同時に、その周辺に在る広大な関連分野への貢献が同時に期待されるのは当然の成り行きと考えられる。その意味で、最近設立

a-18

された連携研究センターに対する期待は大きい。同時に、広い科学的・技術的・更には産業的視野で、関連する諸分野の中から有効な仮題を拾い出すことは極めて困難な作業である。
最近設立された連携研究センターは、周辺分野に深く関連し、産業応用にも深く関わる広範な領域を広い視野で見渡した上で、興味深い課題を抽出し、有効な共同研究を可能にしている。このことは共同利用センタ
ーとしてのNIFSの存在意義を高めるとともに、核融合という新エネルギー源開発研究事業全体の評価を高める
可能性を持ち、特筆すべき新展開である。この領域での今後の発展を大いに期待した。
なお、以前から、関連分野の NIFS 活動として世界的に高い評価を受けて来たものとして、プラズマ中に於ける原子・分子過程がある。これは応用の立場からは地味な存在ではあるが、広範囲の科学技術の基盤として、特に材料科学や計測技術など、諸産業技術の基盤として重要な領域を支えるために必要なばかりでなく、諸学術分野の基盤として不可欠な知見を蓄積してきた。今回の報告においては地味な存在ゆえに目立つ形
での成果報告は行われなかったことはやむを得ぬとして、やはりNIFSの地味ではあるが有意義な学術貢献の一つとして、従来の貴重な蓄積をさらに充実・発展させることを期待したい。
４． その他の特筆すべきこと
午後に行われた報告「最近の研究成果、トピックス」において行われた４件の若手研究者の報告は、優れた若手研究者の育成が確実に進んでいることを示すものとして特に印象的であった。NIFS のような恵まれた環
境で研究に従事することは、若手研究者にとって極めて恵まれたことであるに違いないが、最近の情勢は、研究の「評価」の厳しさ故にともすれば若い人材が浪費され、優れた資質を伸ばすことが困難になる場合を数多く見て、このような情勢下で果たして将来の学術を担う優れた研究者が育成し得るのか不安になる場合を少なからず見聞する。
NIFS がこれらの優れた研究者を育成に成功しつつあることは、その研究活動の健全さを示すものであって、わが国の核融合研究の未来を期待させるものであることを付記したい。
５． 全体的評価
以上のように、核融合科学研究所の研究活動は、磁場閉じ込め核融合研究の世界の中心の一つとして、優れた成果を挙げ、我々の期待に十分沿うものとして高く評価する。
６． 今後への期待
今後も世界の大型装置による磁場閉じ込め核融合研究の中心の一つとして現在の活動を益々発展させる
方向で進むべきと考える。
一方で、世界の情勢は必ずしも磁場閉じ込め核融合にのみ集中しているわけではない。特にアジア地区においては、中国と韓国において慣性核融合研究の拠点が作られ、活発な研究活動が行われつつあることは注目に値する。
わが国の慣性核融合研究は、今日まで主として大阪大学レーザーエネルギー学研究センターで行われ、特に最近同グループが発見した高速点火方式には多くの研究グループが注目し、その線に沿った研究が行われつつある。しかし、現状の日本国内の大学でこれらの活動に競うことは極めて困難な状況にある。
NIFS に於いて慣性核融合をどう取り扱うかを、わが国の核融合研究計画の将来計画として早急に策定し、NIFS の計画の一つとして取り上げる方向で検討されることを切実に期待したい。

a-19評価者: H
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績総評として，LHD プロジェクトはファーストプラズマ後，長きに渡り継続されてきた結果，非常に成熟した核融合研究プログラムとなり，現在世界中の実験プログラムを代表するものである。私的観点を述べると，これはひとえに NIFS および LHD プロジェクトの指導力，また，LHD プロジェクトを支える NIFS 専門職員や技術職員の努力の結果であると思う。LHD プロジェクトはまた，国内外の研究者や研究機関に研究協力を促し，繋がりを深め，核融合科学における効率的科学プログラムの実施および人材開発に取り組んできた。さらに，LHD 実験という現実的環境の中で指導と教育を行うことにより，世界に通用する一流の科学者を輩出したことについて，大いに評価したい。
新たに設置された垂直方向 NBI とともに，高密度状態での高イオン温度達成は，前回の評価会議から大きく飛躍した成果である。 今期の実験でイオン温度輸送が改良され，新古典輸送のレベルに到達している。
5.1％という高ベータ達成および定常運転時の持続値 4.5%は，ともに当初目標あるいは予測を上回る結果である。磁場構成およびトポロジーに関する詳細研究では，非常に優れた成果を上げてきた。
高イオン温度実験，高ベータ研究とともに，IDB による高密度，高圧力放電の達成も極めて重要な進展である。超高密度勾配条件下で計測された拡散係数は，詳細に研究されている。
定常運転研究において，ダイバータ板上にかかる熱負荷の制御，およびダイバータ板熱伝導率改良が効果的であったことが証明され，よって，今後計画されている改良はより確信的なものとなるだろう。
総評および LHD プロジェクトに関する功績のまとめとして，LHD 運転は未だ力強い前進の途にあるが，イオン
温度，電子温度，改良高ベータ，電子密度，定常運転，これら全てが LHD 実験目標の当初予測を上回っている。よって計画中の改良が実施されれば，更に優れた結果をも望めるだろう。

b) （課題に順じた）専門研究(i) 3D-MHD 特性を用いた高ベータ研究
上記で述べたとおり，LHD の高ベータ研究は，MHD 平衡，MHD 安定性および輸送を含む全ての課題において，研究の深さおよび成熟度を実証している。磁気軸を用いた MHD 平衡研究，平衡位相と比較したアスペクト
比変化により，高ベータの達成方法および平衡ベータ限界を避ける方法が示された。
MHD 安定性分野では，磁場レイノルズ数への明確な依存性を明らかにした。また，線形安定性研究によって，抵抗性交換型モード安定性予測と実際の実験環境の区別が可能になった。Mercier モード，低 n 交換性モード，高 n バルーニングモードといった理想的モードの詳細研究が継続されており，MHD 安定性の特性，および分布や閉じ込めとの関係に関する共通理解への可能性が生まれた。
(ii) 高密度運転
高密度プラズマ達成に関しては，ペレット入射と粒子制御が LHD で研究されてきた。多様なペレット入射方法
とともに，それらの成果が発表された。この高密度研究において，LHD の IDB プラズマは高密度勾配で生成される。IDB ショットの再現性が実証され，IDB の輸送特性が詳しく研究されてきた。

a-20

高密度研究において最高密度が達成され，連続ペレット入射を用いて高密度ショットの準定常保持が実現された。これらの成果によって，将来的アップグレードおよび炉研究における改善点が示された。

c) 将来計画
近い将来実施予定のアップグレードにおいて，NBI，ICH，ECH 加熱パワーの拡充は，これまで様々な分野で実証されてきた LHD 実験の進展を継続していく上で，極めて重要である。また，閉ヘリカルダイバータの展開
も，ダイバータ板への粒子熱負荷の制御性を向上させる上で重要になるだろう。
重水素燃料を用いた実験を行うことで，同位体効果を理解する機会となり，既に素晴しい性能を実証済みの
LHD の性能を更に引き立てるに違いない。
(2) シミュレーション科学プロジェクトa) 概要と功績報告の中で，3 つの主要なシミュレーションの取り組みが紹介された。第一の取り組み，数値試験炉を使った
LHD・磁場閉じ込めシミュレーションが，3 件の中で 1 番の重要性を占める。この取り組みの目覚しい進展があり，LHD 実験において，近年性能向上を行う上で、首尾一貫性があり、より強力なものとなった。私個人の意見
では，シミュレーション分野の急成長は，実験結果の理解向上や LHD 実験の性能向上に大きく貢献し，将来的にも貢献し続けるだろうと思われる。さらに，理論研究と乱流シミュレーションが非常に上手く作用し，互いに良いフィードバックを生み出したことにも注目したい。これらの取り組みが LHD 実験，そして閉じ込めに関する理解向上に貢献したことは疑いようがなく，よって，目標値の向上も当然のことだと考えられる。
レーザー核融合の高速点火シミュレーション，磁気再結合現象の PIC-MHD シミュレーション，およびプラズマ
材料相互作用の PIC-MHD シミュレーションが，大きく進展したことは注目に値する。
b) （課題に順じた）専門研究
磁場閉じ込めシミュレーションプロジェクトにおいて，炉心プラズマ流体モデル，炉心プラズマ運動モデル，周辺プラズマモデル，および多階層統合シミュレーションを使った階層拡張シミュレーションの成果が発表され，大きな進展と素晴しい成果が紹介された。特に TASK3D コードの開発および LHD プラズマ解析への応用は，シミュレーションと実験の将来的な相乗効果を考える上で，極めて重要な進展を遂げた。
乱流輸送とゾーナルフローシミュレーションにおいては，他の主要グループとの強力な研究連携とともに，NIFSのこの取り組みにおける世界的役割が示された。急成長した能力は極めて素晴らしく，支援の面でも優先度を高くするようお勧めしたい。

c) 将来計画
提案された磁場閉じ込めシミュレーションプロジェクトの将来計画は，よく提起されていると思う。階層拡張シミュ
レーションの改良および数値試験炉レベルへの統合には相当の努力を強いられるだろうが，挑戦し甲斐もあるだろう。現行レベルの ITG 関連乱流シミュレーションに関する電子輸送研究とともに，粒子輸送のための乱流シミュレーションおよび運動量輸送に関する進展を期待したい。
(3) 連携研究a) 概要と功績

a-21

連携研究推進センターは，非常に短期間の内に大学，産業界，また，他の研究機関と行ってきた多方面での連携活動において，非常に素晴らしい発展を遂げた。原子分子および境界プラズマデータグループの再編成
は，PWI，移動表面式プラズマ対向壁概念研究，および不純物イオンを用いたプラズマ計測などにおいて良い成果に繋がった。
スピンオフ技術を生かした産業連携では，マイクロ波技術の数々の応用により，大きな進展が見られた。
大型望遠鏡の ZPF セラミックを含む他研究機関との連携協力は，核融合スピンオフ応用という面で注目に値する。

b) 将来計画
産業や他の研究機関といった 2 つの研究協力分野の将来計画に関しては，これまでの実績の延長である。しかしながら，マイクロ波応用の他にも技術を展開していくことが望ましい。LHD は多様なスピンオフが可能な先進機能を多数備えた装置であり，新たな応用方法を開拓していくための体系的アプローチの追及は，価値あるものである。
ITER 協力および BA プロジェクトにおいて，更に強力な姿勢で従事することも期待される。これまでに蓄積されたエンジニアリング能力と技術的ノウハウを活かし，NIFS は ITER および BA プロジェクトの成功に向けて，大いにその貢献が期待される。よって，ITER 活動に対する所内優先順位を現在以上に上げることが求められる。
(4) 炉工学研究a) 概要と功績
炉工学研究センターは，ブランケット材料，ニュートロニクス，および超伝導マグネット材料の 3 分野を主軸として研究を行っている。ブランケット材料システム分野は，素晴らしい成果とともに着実な進歩を遂げてきた。ニュートロニクス分野は，現在発展の真っ只中にあり，成果を生み出している。超伝導マグネット材料に関しては，
現在，中性子照射研究に大きく貢献しているところである。

b) （課題に順じた）専門研究
炉工学研究センター独自の貢献として，長寿命液体ブランケットの開発が報告された。V 合金やフリーベなど
ITER TBM 関連の研究は，着実に発展してきた。詳細研究や開発も現在進行中である。
c) 将来計画
炉工学研究センターの将来計画の方向性は，DEMO 炉に向けたシステム統合をよく考慮されている。しかしながら，IFMIF および他の中性子源などの中性子材料研究のために，今以上に努力および優先する必要があるだろう。
2. その他
特別評価の締めくくりに当たり，NIFS をここまで発展させた本島修教授の指導力を賞賛したい。所長任期以前の彼の LHD 設計，建設，および運転に向けた貢献に関しては，今では広く知られているところであるが，NIFS所長として 6 年間の任期中に築き上げた功績は比類なきもので，彼に並ぶ研究者となることは，決して容易ではないだろう。
しかしながら，LHD 実験や NIFS 若手研究者およびエンジニアの指導者は，LHD 実験の新たな領域そして，

a-22

その先に突入していくと強く信じている。効果的な進化を遂げるには先見の明をもつ指導力が求められ，活発な若手世代に責任職への門戸を開いていくことが重要になるだろう。
繰り返しになるが，本島教授のような素晴らしい指導者を持つ研究機関を評価させていただく機会に恵まれ，心から光栄に思う。

a-23評価者: I
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績
大型ヘリカル装置（LHD）で達成したプラズマ性能は，非常に素晴らしい。電子温度と密度の目標パラメータ，
イオン密度，定常運転放電時間，そして，体積平均ベータが達成もしくは更新された。現在記録されている中心部イオン温度（5.2keV）は，目標（10keV）の約半分であるが，アルゴンガスを使用した場合の中心部イオン温度が 13.5keV を記録したことは，注目に値する。
b) （課題に順じた）専門研究
新しく増設された 7MW，40keV 垂直方向 NBI により，イオン温度およびイオン熱輸送向上に繋がった。非常に興味深いこととして，イオン温度勾配が増加するに連れ，外向き対流によって炭素不純物ホールが形成される
ことが発見された。対流は新古典的理論に矛盾しており，明らかに異常輸送である。不純物ホールは，非常に印象的な効果である。
また，高体積平均ベータ値（最大 5.1%，エネルギー閉じ込め時間の 85 倍持続値 4.8%，同 150 倍で 4.5%）の達成は驚異的である。追加熱機器増設によるベータ値の継続的向上は，ヘリカル型閉じ込めシステムにとって，非常に有望な結果だといえる。
「内部拡散バリア」によって，LHD が達成した超高密度に関しては，FFHR への可能性を繋ぐものとして，非常に重要である。（これは，2008 年国際土岐コンファレンスでの主要トピックであった。）ペレット入射の連続最適化は，高密度核融合炉シナリオを追求していく上で，不可欠な研究課題である。
高密度・高ベータプラズマ境界面のエルゴディック層における輸送は，重要な研究テーマである。3 次元境界
輸送コード EMC3-EIRENE が，実験データ解析用に使用された。
とりわけ，アルヴェン固有モードに起因する高速イオン輸送のコードシミュレーションとコンビで実施されたシンチレータプローブを使った高速イオン損失計測では，非常に上質のデータが得られた。
個人的には，高ベータ MHD 実験に関する専門的発表（榊原博士）およびヘリカル炉用高密度運転に関する発表（坂本博士）を高く評価したい。これら双方に見られた実験データとシミュレーション結果の比較は，高く評価できる。例えば，高-n バルーニング・モードの研究を可能にする高精度 MHD コードの開発により，予測範囲が大幅に拡大された。両発表において，次の段階の研究計画が明確に示された。当然ながら，今後の外部評
価委員会においても同様な特定のトピックスに関する説明を期待したい。

c) 将来計画
LHD には 4 つの短期計画がある。： (1) 追加熱機器の向上，特に 5 台目の NBI ライン増設，(2) 閉ヘリカル
ダイバータの設置，(3) 重水素プラズマ放電の開始，(4) FFHR に向けた設計研究の継続，これらは前進する上で，重要なステップであり，積極的な追求姿勢が望まれる。今後の外部評価委員会において，これらの将来計画の更に詳しい内容を伺ってみたい。
(2) シミュレーション科学プロジェクトa) 概要と功績

a-24

シミュレーション科学研究部は，多数の成果を上げ，招待講演や出版物においても，極めて生産的である。結果として，同研究部の概要説明は多岐にわたる研究トピックを取り上げねばならず，詳細にまで至らなかったわ
けだが，午後の詳細な発表は，これらの不足を補完するものであった。
とりわけ，傑出した研究例として，ジャイロキネティックシミュレーション，マイクロ乱流およびマクロ MHD 間の多階層相関，高エネルギー粒子シミュレーション，無衝突リコネクション，高速点火の新たな目標設計に導いたレーザー核融合シミュレーション，などが挙げられる。
同研究部は，理論・データ解析部門と上手く連携しているように思われる。外部グループや研究者との連携協力にも尽力している。近年，JIFT の客員教授と共著で発表した論文の数々は，非常に素晴らしく，注目に値する。
シミュレーション科学に関する年次シンポジウムは，過去 2007，2008 年に開催され，より中身の濃い会議へと発展し続けている。2008 年のシンポジウムには，約 90 名が参加した。
シミュレーション科学のためのスーパーコンピュータのリプレイス（77 TFlop, 16 TByte）の選定が完了したと，
2008 年 9 月に発表された。2009 年 3 月より，運転開始を見込んでいる。 数値試験炉プロジェクトの進行に当たって多用されるだろうことは言うまでもない。
昨 年 も 指 摘 し た と お り ， 「 hierarchy-extended （ 階 層 拡 張 ） 」 ， 「 hierarchy -integrated （ 階 層 統 合 ） 」「hierarchy-normalized（階層繰り込み）」の意味が未だ不明瞭である。もう少し国際的に許容され，理解されている専門用語の使用を提案したい。
超一流のシミュレーション科学知識を持つ研究所として，NIFS には，近年 ITER 用に新設されつつある統合モデル専門家グループへの参加が望まれる。

b) （課題に順じた）専門研究
近年発行された数々の出版物（昨年の Physical Review Letter を含む）または 2008 年度に開催された 3 つの国際的に大きな会議（American Physical Society, International Congress on Plasma Physics, and IAEA Fusion
Energy Conference）で招待講演に選ばれたことから証明されるとおり，ジャイロキネティックシミュレーション研究
は，世界的に認められている。本研究についての専門発表（渡邉博士）は素晴らしかった。特に，ヘリカルリッ
プルに閉じ込められた粒子の径方向ドリフト運動の効果を導入したことにより，内寄せプラズマでの実験観測と非常によく合致する ITG 熱輸送が導かれたという発見は，非常に興味深い。これらのジャイロキネティックシミュ
レーションは，現在その理論的予測を実際に LHD でテストするための，具体的な実験を提案できる段階にあると思われる。 計画されている ETG 乱流やゾーナルフローに関する研究は，非常に重要である。 熱輸送に加え，運動量輸送や異常粒子輸送研究も考慮されたい。
LHD 高密度運転におけるダイバータ，高ベータ運転におけるエルゴディック境界層の重要性を考慮すると，境界プラズマ物理に関する理論・シミュレーション研究の強化が有益だと思われる。特に，LHD 用ダイバータレッ
グの一次元流体モデルは，二次元あるいは三次元モデルに拡張し，キネティック効果を加えるために一般化すべきである。
FIREX のレーザーシミュレーションに関しては，pre-pulse 加熱およびコーンのフォーム構造の追加という新たな構想により，性能は大幅に向上するだろう。
現実問題（磁気圏サブストーム等）を解決するため，磁気リコネクションシミュレーションを用いることを推奨したい。リコネクションシミュレーションの現実的適用例として，他には太陽コロナループが挙げられる。

c) 将来計画a-25

LHD・磁場閉じ込めシミュレーションプロジェクトに関する中間計画に，14 の目標が掲げられている。これらは全て妥当だと思われる。目標達成が LHD 運転または理解に与える影響について，更にお聞かせいただきたい。
レーザーシミュレーションプロジェクトの中期計画目標は，NIFS で 1 人の研究者のみが同プロジェクトに携わっていることを考えれば，大変野心的だと思われる。
プラズマ複雑性シミュレーションプロジェクトの中期計画目標は，妥当である。
数値試験炉開発への目標は，極めて意欲的である。この包括的コードを表示しているフローチャートに加え，短期計画への具体的ステップが明示された構想を拝見したい。
LHD 実験プログラムは，シミュレーション・理論的解釈で解明されるだろう興味深い物理的側面から，不純物ホール，密度バリア，超高ベータ運転等々，斬新な成果を上げ続けている。シミュレーション科学研究部には，これらの研究にさらに着目し，追求し続けていただきたい。
(3) 連携研究a) 概要と功績
連携研究推進センターでは，幅広い分野で多彩な活動が行われている。
同センターの内部組織は，研究センター内にあった原子分子グループを境界プラズマデータグループへ変
更，産学連携推進室内に基礎イノベーション科学技術関連グループを追加，（キッズ・エネルギー科学館を含む）サイエンスコミュニケーション部門の新設など，2008 年に一部改組された。
改組後のセンター組織図において，「collaboration」，「coordination」，「cooperation」が，それぞれ違う意味で用いられているのか，また，同じ単語として認識されているのか分からない。
PWI の分野では，連携研究推進センターは，液体・固体リチウム移動壁コンセプトに関して研究を行っている。
本研究が，各国研究グループが実施しているリチウムプラズマ対向壁研究と如何に異なるのか伺ってみたい。
また，新たな成果が明確にされていない。最近では 2008 年核融合技術シンポジウムで長山博士が論文を発表している（が，同センターの Web ページ上に彼の名前は見当たらない）。
不純物イオンの衝突輻射モデル開発研究は，LHD の境界プラズマ診断計測と関連する。これらのモデルが太陽プラズマデータを分析する外部連携の基礎を築いたとのことである。
プラズマ物理，材料科学，および原子分子物理を組み込んだトリチウムリサイクリングのシミュレーション開発研
究は，ITER および他の燃焼プラズマ実験にとって，極めて重大な課題だと言えよう。PSI および ICPP 会議で発表された本テーマに関する 2 本の論文は，何れもジャーナル出版が認められた。同分野での更なる研究発展が望まれる。PWI やトリチウムインベントリーおよびリサイクリングに関する同センターの研究活動は，炉工学研究センターが実施する同様の研究と調整・統一化できるのではないだろうか。
FIREX 高速点火シミュレーションに関しては，既にシミュレーション科学研究部が研究発表の場で（共同研究として）報告しており，新たに連携研究推進センターの報告に含まれる理由が不明瞭である。
新しいセラミックを目指したマイクロ波焼結技術の研究が，同センター活動の大部分を占めている。同研究は，次世代型巨大望遠鏡用ミラーの建設に応用できるものとして，非常に重要である。また，本研究を通して，産業界と強固な連携協力体制を築くに至った。これに関連して，磁場変化によって発生したエネルギーに関するモ
ンテカルロ・シミュレーションは，高い注目に値する。これにより，キュリー温度以上での自発的磁化消失に関する興味深い結果が見出された。

a-26

NIFS が核融合アーカイブズを支援していることは高く評価される。同アーカイブズは，これまで 18,000 の文書を収集してきた。データベース上のイベント数について，1997 年から単調に増加していたものが，なぜ 2005 年
以降，突然落ち込んでしまったのか疑問である。
2008 年後半に開館したキッズ・エネルギー科学館は，NIFS において連携研究推進センターが運営する新たなアウトリーチプログラムであり，非常に興味深い。NIFS のロビーに設けられている展示室をゆっくり観覧して回り，様々な展示を楽しませてもらった。地元学生や，LHD／バーチャルツアーに訪れた見学者も各展示物に心奪われることだろう。
新たに設けられた，教員のための「サイエンス・コミュニケーション」コースも，斬新で素晴らしいアイデアである。

b) 将来計画
コロナ加熱を調査するための衝突輻射モデル開発計画に関する記述を除き，将来計画に関して明確に記述されていなかった。プレゼンテーション上で報告された現在の研究が，継続されるのだろうと推測される。
(4) 炉工学研究a) 概要と功績
炉工学研究センターには素晴らしい設備が整えられており，大学研究グループとの研究協力推進に役立つだろう。
同センターは，LHD の工学的課題，FFHR，および安全コスト評価の面で，炉工センター外に所属する NIFS
研究者と連携研究を進めているほか，国内大学の研究グループと 7 件の共同研究に携わっている。FFHR 炉
設計問題，取り分け，ブランケットおよび照射に着目した研究は，賞賛に値する。
炉工学研究センターは，非常に建設的に運営されていると思う。

b) （課題に順じた）専門研究
ブランケット材料システム分野においては，バナジウム合金溶接，溶融塩フリーベ・液体リチウムの強制対流，
および先進コーティング技術といった方面で，新たな成果が達成された。特に，高純度フリーベ下におけるス
チールの低腐食速度を確かめる研究で，日本原子力学会から若手研究者賞を賜ったことは大いに注目したい。長寿命液体増殖ブランケットの開発に関する詳細な報告（長坂博士）は，非常に興味深かった。
ニュートロニクスの分野では，シミュレーション，実験ともに行われている。重要なこととして，これにより試験ブラ
ンケットモジュールおよび DEMO 炉設計に関するコードモデリングの妥当性が確認できる。
マグネット材料システムの分野では，大学，産業界，および他の国立研究所（物質・材料研究機構，日本原子力研究開発機構）との連携協力を通して，超伝導マグネット材料への中性子照射効果を調査している。
過去 3 年間に発表された多数に及ぶ各種論文を，表を用いて発表していただけてありがたかった。研究者 7名と学生 3 名しか在籍しないことを考慮すれば，炉工学研究センターは 3 年間で非常に多くの論文を発表してきた。これら論文の多くは共著である。同センターが論文執筆および出版の推進に，意識的に取り組んできたことが伺える。

c) 将来計画
ブランケット，ニュートロニクス，およびマグネットの 3 研究分野ともに，明確な将来計画が提示された。

a-27

2. その他
核融合科学研究所は，同研究所が掲げる三重のミッション目標について明瞭に記述している。これらは，(1)
研究－実験，理論および工学，(2) 共同研究－国内および国際協力，(3) 教育－大学院生および若手の３項目に分かれている。総体的に NIFS は，これら全てのミッションを強力に遂行している。2004－2009 年度の LHD／シミュレーション／炉工学中期計画は，それぞれ明瞭に述べられている。（共同研究に関しても，同様の中期計画があれば良かったかもしれない。）
NIFS 職員の数は，2007 年度から比べれば，2008 年度は 2%と僅かに増加した。予算は昨年度から若干減少した。（数値上は 0.5％減であるが，実質値では 4,100 万円のマイナスになる）
一般共同研究，LHD 共同研究，双方向型共同研究それぞれの研究テーマ数（および共同研究者数）は，前年に比べて若干ながら，全てにおいて増加した。しかしながら，研究資金は 2,100 万円減少した。また，興味深
いことであるが，NIFS との共同研究に携わった大学および研究機関の総数は，157 校から 144 校へ 8%減少した。
2008 年においては，新たな政府間、外国の大学や研究機関との国際連携，あるいは科学協定は締結されなかった。政府間協定として 6 件，外国の大学や研究機関とは 14 機関，これまでに学術交流協定が結ばれており，これだけでも目を見張る数だと言える。
総合研究大学院大学の学生数は，連携大学の学生が NIFS で博士研究を行ったり，共同研究プロジェクトを通して NIFS で研究している学生研究者がいることから，前年比とほぼ同じ数に留まった。連携大学の学生がNIFS で授業を受ける数は 50%減少した。2008 年には ITER 国際サマースクールが日本で開講された。
特別評価会合での発表のバックグラウンド情報として，NIFS の最新出版物 12 件を提供していただけたことに感謝したい。
今後の外部評価委員会の概要発表において，LHD，シミュレーション科学，共同研究，および炉工学研究センターの活動および進展の度合いを測るものとして，数値基準の導入をお薦めしたい。数値基準の一例として，発表論文，招待講演，特許，卒業学生，共同研究の数等が挙げられる。
私の印象では，NIFS の出版物は年々増加を重ねてきた。近年ジェノバで開催された IAEA 会議の場でも，NIFS の存在が注目を集めていたことは明白である。
午後に設けられた（比較的）若手研究者による詳細発表は，明瞭かつ整然として非常に素晴らしく，このような高い資質を持った人材がいる NIFS の明るい未来を象徴している。実際のところ，今回と同等の高い質の成果
報告の数を 2 倍に増やすことも，今の NIFS なら容易にできるのではないかと推測している。
6 年間 NIFS の所長を務めた本島教授には賞賛の言葉以外見つからない。LHD は，現在世界で最高のヘリカ
ル型閉じ込め核融合装置であり，NIFS は実験，理論シミュレーション，および炉工学を統合したプログラムとともに，世界の核融合科学界をリードする存在である。次期所長におかれては，本島所長が発揮してこられた見事な指導力に則って，効率的かつ生産的に機能している現研究所を引き継がれることだろう。

a-28

2. 評 価 の 概 要
1. プロジェクト活動（研究の目的，成果と課題，研究の質，改善点の提案）(1) 大型ヘリカル装置（LHD）プロジェクトa) 概要と功績--

LHD プロジェクトの成果は大変優れたものであり，核融合エネルギー開発を成功裡に進める上での主要課題を全て網羅している。
過去 6 年間における主な発見のハイライトとして，不純物ホールを伴う高イオン温度，超高密度運転，
MHD 不安定性による大幅な劣化が見られない高平均ベータ，および定常運転などが挙げられる。これら
はヘリカル閉じ込め方式核融合にとって，非常に有望な成果であるといえる。
物理研究も重要視され，これは言うまでもなく，設立当初 NIFS に課された使命に基づいている。また，研究所はトロイダルプラズマの総合理解の前進にも貢献した。
複雑な超伝導システムの安定運転も，優れた技術的成果である。
LHD プロジェクトは，科学プログラムの効率的実践，および核融合科学分野における人材開発に，向けて貢献し，共同研究を強化した。

b) （課題に順じた）専門研究--

磁場配位の最適化および加熱機器の体系的増強により，素晴らしいプラズマ性能が達成された。 高速
ペレット入射とあいまって，新たな運転領域，ディスラプションの無い高密度運転が発見された。
不純物蓄積が抑制された興味深い現象も見出された。
高ベータ領域における MHD 平衡および安定性の問題に対しては，大変成功裡に取り組まれている。 質の高いプラズマ計測技術によって，プラズマ実験の分析および理解の前進に繋がったものと考えられる。
定常運転の発展および核融合条件を満たす核融合三重積を実現するためにも，加熱機器の増強，閉ダイバータ構成および重水素運転の効率的導入を実践すべきである。
内部拡散障壁(IDB)，コア密度崩壊(CDC)，不純物ホールといった新発見の物理的理解について，更なる追究が求められる。運動量輸送について，特に不純物輸送との相関性について，更に重点を置いて取り組まれたい。
注意深い実時間配位制御によって，ベータ値は更に向上すると思われる。
高速イオン損失の計測および関連するシミュレーションの知見により，実験データの解釈が大きく進展した。
炉研究は，現在の DEMO 研究との密切な関連性を持つべきである。グリーンワルト限界が無いことで，より高密度・低温状態での点火に関する展望が拓けたことは明白である。これらの炉条件下における熱不安
定性，中性粒子輸送，不純物生成および輸送の役割について，全貌の理解を得ることは有益だろう。

c) 将来計画-

重水素実験，加熱能力増強，閉ヘリカルダイバータ，FFHR 設計研究の継続といった直近の将来計画は，
よく定義されている。
閉ヘリカルダイバータの段階的導入に関しても，実験スケジュールに影響を及ぼさないよう，よく計画されている。
装置の物理的限界への挑戦を目標に，全力投入していくことが望まれる。
プラズマパラメータの改善に向けて，NIFS の傑出した技術力・計算機能力に基づく斬新かつ詳細な方法を模索していただきたい。

a-29

(2) シミュレーション科学プロジェクトa) 概要と功績--3 件のプロジェクトを平行して進められるようになる程，シミュレーショングループが発展してきたことは高く評価される。特に LHD 磁場閉じ込めプロジェクトにおいては，国際的競争力をもつ高レベルな成果を着実に積み上げてきた。シミュレーション研究の急成長は，実験成果の理解を深めるとともに，今後の LHD
性能向上に貢献し，また，将来的にもそうあり続けるだろう。
これらの活動を統合し，新たなスーパーコンピュータを最大限に活用することによって，「数値試験炉プロジェクト」を展開させていくという方向性は理にかなっている。
レーザー核融合シミュレーションプロジェクトおよびプラズマ材料相互作用に関する数値研究により，同グ
ループの影響力は更に拡大されるだろう。
学際的アプローチをとるこれらのプロジェクトは，様々な研究機関における関連事業を取り纏めている。

b) （課題に順じた）専門研究--

ヘリカルプラズマにおける ITG 乱流およびゾーナルフロー形成の研究は，目覚しい進展を遂げている。新
古典輸送の小さい配位では，ゾーナルフローが高い振幅で維持されることが明らかにされた。また，径電場効果においても研究が進められた。これらのシミュレーションは現在，予測の検証的 LHD 実験を提案できる段階にまで到達している。
TASK3D コードの開発および同コードの LHD 実験への応用は，シミュレーションと実験の将来的な相乗効果に向けて，大変貴重な進歩を遂げた。
詳細な計測データを含めることは，現在の傑出したシミュレーション成果の更なる増補に繋がるだろう。
トカマクとの対比に気を配られたい。
LHD 実験に関連した目標は，適切に定義されている。CDC, IDB, 不純物ホール，また，運動量輸送といった最新かつ話題の問題が，これらに含まれていることは必須である。
一般科学に関する重要課題（自己組織性，磁力線再結合，および全体統合プロジェクトなど）について
は，NINS における取り組みの統合がなされつつある。

c) 将来計画-

数値試験炉プロジェクトは，直近の計画に関して，明確に定義された具体的段階が準備されており，高く評価される。
ITER モデリンググループとの実りある協力，支援が望まれる。
重水素実験に焦点をあてたシナリオの取り組みが必要である。
新たなスーパーコンピュータに関する計画は，高く支持できる。
これらのシミュレーションプロジェクトが，幅広い分野における階層現象の統合研究を推進する上で，先駆者的役割を担っていくことを強く期待したい。

(3) 連携研究a) 概要と功績--

連携研究推進センターは，適切に組織されており，多方面の科学・産業分野に LHD 実験の波及効果を高めつつ，トップクラスの活動を行っている。このことは，原子分子過程，PWI，材料科学，原子物理学，レーザー核融合，計測，および基礎プラズマ研究の分野で特に顕著である。
キッズ・エネルギー科学館のようなアウトリーチ活動も高く評価される。
新たに開設された教師のための「サイエンスコミュニケーション部門」も，素晴らしいアイディアである。

b) 将来計画a-30

-ITER，BA，JAEA，および ICF(FIREX)研究との密切な連携が強く推奨される。DEMO 関連課題に関するした先駆的研究の推進が必要である。
トリチウムの取り扱いに関する問題に殊更重点を置くべきである。
幅広い科学分野の基礎として，原子分子データベース活動の更なる前進を強化されたい。
LHD はスピンオフの可能性を秘めた多彩な先進技術を兼ね備え，新用途の開拓に必要な体系的アプローチを追究している。
アウトリーチを様々な団体や市民にまで拡大することも可能だろう。これらは NIFS の将来計画に関わるものであり，NIFS の大学共同利用体制を活用しつつ，関連コミュニティとの議論を進めるべきである。
また，各研究トピックの最終目標，どのようなブーメラン効果が得られたのかについて，明確にすることをお勧めしたい。

(4) 炉工学研究a) 概要と功績--

研究課題は適切に選択されており，国際的にも価値のある成果を上げている。炉工学研究センターは，核融合炉に向けた最大の懸案事項（ブランケット，ニュートロニクス，マグネット等）を選定することにより，重要な成果を上げてきた。
彼らの功績を理解する上で，予想される炉スケールを明確化してみる価値はあるだろう。

b) （課題に順じた）専門研究-

炉工学研究センターは，ブランケット材料システム，ニュートロニクス，およびマグネット材料システム分野の専門家で構成されている。長寿命フリーベおよび Li ブランケット研究は極めて素晴らしい。
NIFS-HEAT-2 は，不純物汚染を防いで溶接することに成功している。
高速フィードバックシステムが，ニュートロニクス設計に統合された。 ニュートロニクス研究は，間近に迫っている ITER 運転にとっても，歓迎される。
超伝導開発でハイレベルな成果を上げており，高く評価できる。

c) 将来計画-

周辺構造，電流リードに関する課題等について，更なる研究協力の推進が求められる。
超長時間での熱クリープの研究のために，長期間のクリープ試験を継続する必要がある。
複雑形状における中性子計算の向上，および高温超伝導に関する更なる検証計測や研究が望まれる。
IFMIF や他の中性子源といった中性子照射下での材料研究に向けて，さらに尽力し，優先順位をあげられたい。
開発計画がどの程度 ITER および IFMIF スケジュールに左右されるかについて，更に詳しく分析するとよいだろう。
ヘリカル炉計画およびトカマク／ヘリカル炉間の対比が望まれる。

2. その他--

本島修所長の優れたリーダーシップにより，NIFS は最先端核融合研究における国際的先導者としての地位を確立した。これらの成果は，幅広い研究活動の周到な協調，および同研究を熱核融合という主要目
標に集約させたことにより達成された。これらは世界的関心を集める LHD 実験成果やシミュレーション科
学の成果のみならず，付随する全ての科学プログラム，多数の研究機関との連携協力，技術プログラム，
および広報関係プログラムまでも網羅してきている。
成果報告のクオリティは素晴らしく，若手世代の発表には目を見張るものがある。彼らのような若い研究者が世界に通用する成果を上げているのは，大変心強いことである。また，これは NIFS が将来に向けて準

a-31

-

備万端であることの証でもある。次回の評価会議では，現在の勢いや世界的先導力をいかにして長期間保ち続けていくかについて，着目していただきたい。
現在の成果と更なる連携協力の発展に基づく NIFS における研究の進展，新たな科学的潮流の萌芽を期
待したい。

a-32

(b)

Attached Documents

Contents

1.

Participants List of NIFS Special Review Meeting ･･･････････････････ b-1

2.

Program of NIFS Special Review Meeting ･･･････････････････････････ b-3

3.

Viewgraphs ･･････････････････････････････････････････････････････ b-5
3-1

Introduction of NIFS Activities ･････････････････････････････････ b-5

3-2

Development of Net-Current Free Heliotron Plasmasin Large Helical Device ････ b-18

4.

3-3

Simulation Science in NIFS ･･･････････････････････････････････ b-26

3-4

Activities of The Research Coordination Center ････････････････ b-37

3-5Highlights for long-life blanket and SC magnet materials ･･･････ b-58

3-6

High-Beta and Related 3D MHD Characteristics ････････････････ b-74

3-7

High Density Operation and Its Prospect for Helical Reactor ････ b-90

3-8

Turbulent Transport and Zonal Flows ････････････････････････ b-103

3-9Development of long-life liquid blanket ･･･････････････････････ b-121

Resume of NIFS Special Review Meeting ･････････････････････････ b-139

1. Participants List of NIFS Special Review Meeting
No.

Name

Title, Affiliation

Reviewers
1 Dr. Carlos Alejaldre

Deputy Director-General for Safety and Security, ITER, France

2 Dr. Gyung-Su Lee

President, National Fusion Research Institute, Republic of Korea

3 Prof. Hiroshi Takuma

Advisor (Emeritus Professor, the University of Electro-Communications)

4 Prof. James W. Van Dam

Director, Institute for Fusion Studies in the University of Texas at Austin, USA

5 Prof. Kyoji Nishikawa

Advisor (Emeritus Professor, Hiroshima University)

6 Prof. Michael Tendler

Advisor (Professor, Royal Institute of Technology, Sweden)

7 Prof. Robert Wolf

Professor, Max-Planck-Institute for Plasma Physics, Germany

8 Prof. Satoshi Itoh

Advisor (Emeritus Professor, Kyushu University)

9 Prof. Thomas Klinger

Professor, Scientific Director of Max-Planck-Institute for Plasma Physics, Germany

NIFS members
10 Prof. Osamu Motojima

Director-General

11 Prof. Shigeru Sudo

Deputy Director-General / Executive Director, Department of Simulation Science

12 Prof. Akio Komori

Executive Director, Department of Large Helical Device Project

13 Prof. Hiroshi Yamada

Director, Research Operations Division, Department of Large Helical Device Project

14 Prof. Shinsaku Imagawa

Director, Fusion and Advanced Technology Systems Division, Department of Large Helical Device Project

15 Prof. Noriyoshi Nakajima

Director, LHD and Magnetic Confinement Simulation Division, Department of Simulation Science

16 Prof. Shoichi Okamura

Director, Fusion Frontier Simulation Division, Department of Simulation Science

17 Prof. Motoyasu Sato

Director, Coordination Research Center

18 Prof. Akio Sagara

Director, Fusion Engineering Research Center

19 Assoc. Prof. Satoru Sakakibara

Associate Professor, Research Operations Division, Department of Large Helical Device Project

20 Assoc. Prof. Ryuichi Sakamoto

Associate Professor, Research Operations Division, Department of Large Helical Device Project

21 Assoc. Prof. Masayuki Yokoyama

Associate Professor, Theory and Date Analysis Division, Department of Large Helical Device Project

22 Assoc. Prof. Tomohiko Watanabe

Associate Professor, LHD and Magnetic Confinement Simulation Division, Department of Simulation
Science

23 Assoc. Prof. Takuya Nagasaka

Associate Professor, Fusion Engineering Research Center

24 Mr. Yasuo Kainai

Director, Department of Administration

25 Mr. Yutaka Fukui

Head, Planning and External Affairs Division, Department of Administration

26 Mr. Sadao Azuma

Leader, Planning Office, Planning and External Affairs Division, Department of Administration

27 Mr. Makoto Tsuda

Chief, Objective Planning and Evaluation Section, Planning Office, Planning and External Affairs
Division, Department of Administration

28 Mr. Kazuma Shimizu

Staff, International Affairs Section, External Affairs Office, Planning and External Affairs Division,
Department of Administration

29 Ms. Shihoko Soga

Staff, Press and Community Relations Section, External Affairs Office, Planning and External Affairs
Division, Department of Administration

b-1

b-2

2.

Program of NIFS Special Review Meeting

December 13, 2008 (Sat.)
Special Room, Restaurant and Conference Rooms 3F, HIDA Earth Wisdom Center
8:30
Opening
8:30 Opening Address (5 min)Director-General, Osamu Motojima
8:35 Introduction of NIFS Activities (20 min)
Deputy Director-General, Shigeru Sudo
8:55 Current status and research subjects, future plans of NIFS (160 min)
[40 min / item (Report 25 min + Q&A 15 min)]
8:55 - 9:35
Large Helical Device (LHD) Project
Executive Director, Akio Komori
9:35 - 10:15 Simulation Science Project
Director, Noriyoshi Nakajima---- Coffee Break (15 min) ---10:30 - 11:10 Coordination Research
Director, Motoyasu Sato
11:10 - 11:50 Fusion Engineering Research
Director, Akio Sagara---- Lunch Break (60 min) ---12:50 - Recent results and topics (240 min)
[60 min / item (Report 40 min + Q&A 20 min)]12:50 - 13:50 High Beta and Related 3-D MHD Characteristics
Assoc. Prof. Satoru Sakakibara
13:50 - 14:50 High Density Operation and Its Prospect for Helical Reactor
Assoc. Prof. Ryuichi Sakamoto---- Coffee Break (15 min) ---15:05 - 16:05 Turbulent Transport and Zonal Flows
Assoc. Prof. Tomohiko Watanabe
16:05 - 17:05 Development of long-life liquid blanket
Assoc. Prof. Takuya Nagasaka
17:05 - General comments from reviewers (40 min)
17:45 - Closing Address (5 min)Director-General, Osamu Motojima
17:50
Closingb-3

b-4

3. Viewgraphs
3-1 Introduction of NIFS Activities

Introduction of NIFS Activities

National Institute for Fusion Science, NINS
Shigeru SUDO
Presentation to the Special Review Meeting
December 13, 2008, Takayama, Japan

Introduction of NIFS Activities
1. Mission of NIFS
2. Organization
3. Collaboration Research
4. Training and Education of Young Researchers
5. Recent NIFS Research Activities
6. Overview of Review Process

2/25

b-5

1. Mission of NIFS
To promote nuclear fusion science and research on
its application, NIFS was established as an InterUniversity Research Institute in 1989
1989.
(1) To promote both experimental research based on the world
largest superconducting device: Large Helical Device (LHD),
theoretical and simulation research, and fusion engineeringresearch.
(2) To promote collaboration research with universities andy and also international
institutes all over the country
collaborations, and to bring up young researchers.
(3) To educate graduate students in the department of nuclear
fusion science of the Graduate University for Advanced
Studies, and also in the other universities.

3/25

Transparency and Accountability of Research Activity
Mid-Term Goal (FY2004-2009)Mid-Term Plan (FY2004-2009)
Annual Plan (done for 2004-2008
2004 2008 every year)
AnnualAnnual Achievements Report 2004-2007 every year
Annual review by the evaluation committee organized
by MEXT (done in 2004-2007 every year)
Research activities are being reviewed by National
Institution for Academic Degrees and University
Evaluation in 2008
NIFS
Number of Staff: 225 (Researchers:133, Technical Staff: 45,
Administrative Staff: 47) (FY2008)
Annual Budget: 10616 MYen (FY2008)

4/25

b-6

Mid-Term Plan (FY2004-2009) Related to LHD
LHD project To maximally utilize the performance of LHD and conduct scientific researches in aneffort to achieve comprehensive understanding of toroidal plasmas and actualize fusion
reactor plasmas. Therefore, NIFS strives to maintain, develop, and improve plasma
heating devices and diagnostics equipments as well as to increase the performance of
LHD plasmas that foresee fusion core plasmas.

Bilateral collaboration researches To work on the clarification of physical mechanism necessary to boost up the plasma
performance as part of bilateral collaboration researches by efficiently utilizing devices
and equipments of research institutions, universities, affiliate institutions, and centers.
With a view to improve confinement property, to actively promote a development of thenext-generation experimental device with an advanced magnetic configuration as acommon subject of the research community.

Internal structure to achieve goals
 In order to produce an intensive research outcome, to establish organizations capableof operating flexibly and effectively. To review functions of research departments andcenters and carry out organizational changes.
 To strengthen collaboration systems with universities and to enhance supporting
systems for researches in universities.

Relevance to inter-university research activities

 To improve the research environment with a view to promote inter-university research
activities and collaboration researches that utilize experimental devices like LHD.
5/25

Mid-Term Plan (FY2004-2009) Related to
Simulation Research and Fusion Engineering
Simulation Research(1) Understanding of the Plasma
To understand and systematize physics mechanism of fusion plasmas
To explore complexity science (nonlinear, non-equilibrium, open system) as basic
researches to support fusion plasma studies(2) Simulation Science
To aim at establishing “Simulation Science” as a new interdisciplinary field
To promote collaborative researches, utilizing large-scale simulators

Fusion Engineering

To contribute progress toward establishment of fusion reactors by leading
activities and summarizing results in the fusion engineering studies throughcollaborations among universities, to enrich facilities and functions for thesestudies, to obtain most advanced results in this field with own activities.

6/25

b-7

(2008)2.Organization

Research Operations Division
High-Temperature Plasma Physics
Research Division

Administrative Council

Department of Large Helical
Device Project

Particle Beam Heated Plasma
Research Division

DeputyDirector-General

LHD and Magnetic Confinement
Simulation Division

Department of Simulation
SciencePublic Relations
OfficeFusion Archives

Division for Healthand Safety Promotion

Theory and Data Analysis Division

Fusion and Advanced Technology
Systems Division

Director-General

R
Researchh IInformationfti
OfficeRadio Frequency Plasma Heating
Research Division

Fusion Frontier Simulation Division
Rokkasho Research Center

Coordination ResearchCenterFusion Engineering
Research Center

Safety and Environment
Research Center

Division of Science Communication
Division of Academic Research
Coordination

Division of Industrial-Academic
Data Research Coordination
Atomic, Molecular and Plasma
Periphery Data Research Center

Department of Administration
Department of Engineering andTechnical Services

7/25

3. Collaboration Researches
conducted by NIFS as an Inter-University Research InstituteThe collaboration researches conductedbyy NIFS are categorizedginto:(1) General collaboration research
339 Research Subjects, 80 MYen

(2) LHD collaboration research
34 Research Subjects, 170 MYen

(3) Bilateral collaboration research
68 Research Subjects, 654 MYen
for FY 2008
8/25

b-8

Number of subjects & collaborators

Bilateral Collaboration

2004

2005

2006

2007

Subjects

43

52

53

59

68

Collaborators

495

625

671

777

866

National Institute for

15 participating inst.
Fusion Science
18 research subjects
Integrated andInstitute of Advanced Energy,pLaboratory
y of ComplexpEnergygy Processes comprehensive

Importance conv
versionImprovement of efficiency
efHeliotron J

13 participating inst.
12 research subjects
Plasma Research Center

understanding of
toroidal plasmas

GAMMA10

Tsukuba Univ.
Physics study of

Kyoto Univ.

Optimization ofconfinement andstability by magnetic
configuration

confinement
improvement byelectric potential

All-out collaborations
in community

TRIAM-1M
Gekko XII

Kyushu Univ. Osaka Univ.

New development
Study of steadystateoperation of high TRIAM-QUEST
temperature plasmas

24 participating inst.
19 research subjects
Research Institute for Applied Mechanics,
Reinforcement ofAdvanced Fusion Research Center

2008

Development of fast
ignition by laser

Human ressource developmen
nt

Fusion Research Community

JFY

22 participating inst.
18 research subjects
Institute of Laser Engineeringinter-operation and collaborations

for FY 2008

9/25

Japanese Fusion Activities
Total Univ. andInstitutes undercollaboration with
NIFS: 144

NIFS
LHD

10/25

b-9

International Research Collaboration
1. Academic Agreement
To promote international research collaborations the following agreements have beenconcluded:(between governments) US-Japan, China-Japan, Korea-Japan, IEA Stellarator, IEA TEXTOR,IEA Spherical Tori: These agreements cover fusion community in Japan. NIFS contributes tosupportt domesticdti researchersh(between institutions) ASIPP-,Max Planck-, Kurchatov-, Kharkov-, ANU-, KBSI-, FZK-, PPPL-,IFS ,Univ.Texas-, ORNL-, UCLA-, Univ. Provence-, GPI- NIFS,
LIA (Kyushu Univ. NIFS, Osaka Univ. – CNRS, Univ. Provence)
2. Collaborative Research Framework for ITER
To promote ITER-related collaboration researches, the organization has been established in
NIFS.
3. International Conferences
To support research activities of domestic researchers by holding international conferences andsymposia. International Toki Conference (ITC) has been held annually, selecting current
topicsp as the main theme. In 2007, the ITC was held jjointly
y with International
Stellarator/Heliotron Workshop with the topics of “Physics of Flows and Turbulence in Plasmas.”
The theme of the ITC in 2008 was “Development of Physics and Technology of
Stellarator/Heliotrons en route to Demo.” The 6th IAEA Technical Meeting on Control, Data
Acquisition, and Remote Participation for Fusion Research in Inuyama, the PET conference in
Takayama, the international LAPD conference in Takayama, US-Japan Workshops were held in
2007.
4. Personal Exchange
To strengthen research activities guest professors have been invited and researchers havebeen sent to foreign institutes. To promote mutual understanding and to cultivate young
scientists, graduate students have been accepted from foreign countries.

11/25

International Cooperation
Governmental Cooperation

Date ofConclusion

IEA Implementing Agreement for a Programme of Research andDevelopment on Plasma Wall Interaction in TEXTOR

Apr.
Apr 13 1978

Agreement between the Government of Japan and theGovernment of United States of America on Cooperation in
Research and Development in Energy and Related Fields

May 2 1979
(Changing to
new scheme)

International Energy Agency Implementing Agreement for CoOperation in Development of the Stellarator Concept

Oct. 2 1992

Core University China-Japan Collaboration Program (CUP)R
Researches
h on Core
C
PlasmaPl& Reactor
R t Technology
T h l
for
f AdvancedAddFusion Reactor

O t 16 2000
Oct.

Japan-Korea Cooperation in the Area of Fusion Energy Researchand Related Fields

Nov. 16 2004

IEA Implementing Agreement for Cooperation on Spherical Tori

Feb. 20 2007

12/25

b-10

Scientific Agreements of NIFS
with Foreign Universities/Institutes
Agreement Conclusion Facility

Country

Conclusion Date

China

Jun. 27 1992

Institute of Plasma Physics, Academic Sinica
Max-Planck-Institut für Plasmaphysik

Germany

May 11 1993

Russian Research Centre,
Centre Kurchatov InstituteRussiaMay 15 1993

National Science Centre, Kharkov Institute of Physics and Technology

UkraineOct. 7 1994

The Australian National University

Australia

May 8 1995

Korea

Mar. 6 1996

Germany

Oct. 6 2005

USA

Mar. 3 2006

Korea Basic Science InstituteForschungszentrum Karlsruhe GmbH, Institut für Technische Physik
Princeton Plasma Physics Laboratory
Institute for Fusion Studies, The University of Texas at Austin

USA

Mar. 6 2006

Oak Ridge National Laboratory

USA

May 25 2006

Institute of Plasma and Fusion Research, University of California, Los Angeles

USA

Nov. 28 2006

University of Provence

FranceJul. 19 2007

A. M. Prokhorov General Physics Institute, Russian Academy of Sciences

RussiaOct. 15 2007

Agreement for the Creation of an Associated International Laboratory (LIA):
Japan (Kyushu Univ., NIFS, Osaka Univ.) – France (CNRS, Univ. Provence)FranceOct. 22 2007

13/25

Formation of Interdisciplinary and International
Network of Research Bases as a member of NINS
Uzbekistan National
Univ.(Uzbekistan)

NSF
(USA)
Kurchatov Inst., GPI
Universities
PPPL,(Russia)
and their annex
UCLA, ORNL,
Max-Planck-Inst.,
Max
Planck Inst., FZK Kharkov InstInst.
institutes
i tit tIFS Texas
T
U
Univ.
i
(Germany)(Ukraine)(USA)
Univ. Provence, CNRSKBSI(Korea)(France)
ASIPP(China)
Hawaii Univ.
Acad. Sinica (Taiwan)(USA)
ANU(Australia)
ESO (EU)

EMBL (EU)NIFS

Promotion of interdisciplinary,international collaboration

Research Cooperation and Liaison Board/OfficeFormation of International
Collaboration Research Base

Formation of interdisciplinary
Collaboration Research Base(together with universities and theirannex research institutes, etc.)(together with EMBL, ESO, MPI etc.)
Policy, Planning of
ALMAInternational Strategy International strategy(Chili)
Board/International
Formation of international
Cooperation Office
network for scientists

NINS

b-11

14/25

4. Training and Education of Young Researchers at NIFS
Postgraduate Education
FY2005

FY2006

FY2007at 2008.11.01
FY2008

Summer / Winter Schools
Seminar in Kashikojima

Jul.28-30

Jul.27-29, Jul.31-Aug.2

Jul.29-Aug.1

Jul.31-Aug.2

Summer Introductory School

Aug.18-24

Aug.7-11

Aug.8-10

Aug.4-8

Asian Winter School

Dec.12-16

Feb.27-Mar.2

Jan.26-29

Feb.3-6

Jul.16-20

Jul.22-25

21
4

22
8

18
2

10
4

6
5

6
7

2

2

2

20

15

7

ITER Int. Summer School
Graduate University for Advanced Studies (SOKENDAI)
Number of students
25
Number of Ph. D awardees
12
Students from associated universities doing degree courses at NIFS
Grad School of Eng., Nagoya U.
11Grad School of Sci., Nagoya U.
7
Grad School of Eng., Hokkaido
1
U.
Students from associated universities taking courses at NIFS
Grad School of Sci. and Eng., U.
14
ToyamaStudent researchers at NIFS under the collaboration research programs
22
23
20
21
(Tohoku U., U.Tokyo,(Tohoku U., Saitama U.,(Tohoku U., U.Tokyo,(Tohoku U., U.Tokyo,
Tokyo Inst. of Tech.,
U.Tokyo, Yokohama Ntnl. Yokohama Ntnl. U., Niigata Tokyo Inst. of Tech.,
Yokohama Ntnl. U.,
U., Shinshu U., Nagoya U., U., Fukui U., Shinshu U.,
Yamagata U., Yokohama
From national universities
Shinshu U., Nagoya U.,
Kyushu U., Kagoshima U.) Nagoya U., Kyoto U.,
Ntnl. U., Fukui U., Kyoto
Osaka U., Yamaguchi U.,
Kyushu U.)
Inst. of Tech., Osaka U., U.
Kyushu U., Kagoshima U.)
Tokushima, Kyushu U.,
Kagoshima U.)
From prefectural or city
10
00universities(Toyama Prefectural U.)
44
54(Sophia U., Seikei U.,(Sophia U., Seikei U.,(Sophia U., Seikei U.,(Sophia U., Seikei U.,
From private universities
Tokai U., Rikkyo U.)
Tokai U., Fujita Health U.) Tokai U., Fukuoka Inst. of Doshisha U., Fukuoka Inst.
Tech., Fujita Health U.)
of Tech.)

15/25

5. Recent NIFS Research Activities
Present View ofLarge Helical Device (LHD)
PelletInjector
ECR
84 – 168 GHz

Plasma vacuum vessel

World largest superconducting coil system
Magnetic energy
1 GJ
Cryogenic mass (-269 degree C) 850 t
Tolerance< 2mm

Local Island
Divertor(LID)

NBI
External diameter 13.5 m
Plasma major radius 3.9 m
Plasma minor radius 0.6 m
Plasma volume
30 m3
Magnetic field
3T
Total weight
1,500 tNBI

ICRF
25-100 MHz

16/25

b-12

Target and Achievements in LHD
Achievements [Final target]
Ion Temperature
Central Ti 13.5 keV
Density31018m-3 (Ar gas)

102

World record of beta value
approaching to plasma pressure
condition

Volume Averaged 
5.1 % (magnetic field of 0.425T)[ 5 % (1-2 T)]Electron Density
1.21021m-3

World record of plasma density

ITER

break-even
break
even

101

(1020m-3 keV s)

Fusion tripple productF

Attainment of temperature
off ffusion
i reactor

Electron Temperature
Central Te 10 keV[10 keV]
Density51018m-3 [2  1019m-3]

Commercial
reactor

Ignition

LHD goal

10010-1 LHD achieved Upgrade
10-2
Existing
Tokamaks

10-3min. hour day monthStored Energy
1.66 MJ[ 4.0 MJ]

10-4
10-1 100 101 102 103 104 105 106 107

Holding time (s)Steady State Operation
31min.45sec. (680 kW) 1.3GJ [1 hour (3,000 kW)]
54min.28sec. (490 kW) 1.6GJ

World record of injected energy

17/25

IDB Scenario and Super Dense Core Reactor• Edge Control

Core fueling by pellet injector
Particle pumping by LID  Low edge density• Confinement Improvement (IDB)

Present Interests : Position sensitivity of IDB foot & MHD stability• New Ignition Scenario (SDCR)

High Density and Lower Temperature Core
Parameters (n, T, ) obtained are encouraging

LHD

Reduced engineering demandand neoclassical ripple transport
20

3

-3

m )

4

Density (10FFHR
1,000 MW
6Tesla25,000 ton

High density operation

5 ● ●Self-ignitiongHigh temperature
operation

2
ITER

1

40m

0

b-13

Contour lines:
Pex
Breakeven
10
20
30
18/25
Temperature (keV)Establishment of Dept. of Simulation Science• New organization: Department of Simulation Science
was established on April 1, 2007
・ Organization of the Department of Simulation Science
Department of Simulation Science consists of 2 division and 1 center,by unifying the previous theory and computer center, and computer andnetwork center
LHD and magnetic confinement simulation division,
Fusion frontiers simulation division,
Rokkasyo research center
Promote three simulation projects under the collaboration with universities andinstitutes: (a) LHD and magnetic confinement, (b) Laser fusion, (c) Complex plasma

・ Symposium of Simulation Science was held every year: at Ceratopia, Toki on
September 6-7, 2007, and at Tajimi on September 24-25, 2008

・ New computer and computer-related resource
New supercomputer has been selected and its operation will start in March 2009
Image analysis system ComplexCope has been developed

19/25

Numerical Test Reactor Project

To create a fusion energy reactor in a virtual space (computer) in order to
optimize properties on physics and engineering, and economical aspects
Application ofimaging science

Hierarchy-extended simulation for precise physics

PetaF
315TF (2012)
77TF (2009)
Upgrade ofSupercomputer

Verification by LHD
data base on
physics andengineering

R&D of system& materials
Modeling

Introduction of physics knowledge to improve predictability
Input
heat &
particles
magnetic
structurecontrol ofheat, particles

outputα particles

neutrons

Reactor design：technological,
economical,& ecologicalcompatibility.
Evaluation ofefficiency

heat, particles

Hierarchy-integrated simulation: to predict
the whole response of macro quantities

Change of condition

feedback
Optimization of helical reactor with integration of high performance plasma andstructure components & system

b-14

20/25

Support system forprogramdevelopment

New Plasma Simulator at NIFS
Large-Scale Parallel Type
Processing Server

Front System

Server for Development:
2.48TF, 1.5TB
Support Staff of residing

Storage system
0.5PB / 2PB

High Speed Network

Front System

High Speed
Network
DeviceRAID

Simulation Laboratory

Upgrade of the supercomputer in March 2009
SR16000: 77TF,, 16TB
From Oct 2012
post SR16000: 315TF, 32TB

Data Processing
ServerFile Server

Firewall

NIFS LAN
Gateway

21/25

Facilities to promote Fusion Engineering Researchbased on collaboration with Universities

22/25

b-15

Activities of Coordination Research Center
Functions: Co-operations for innovation from science and technologies
Iron Ores
Low CO2
N Gas
Growing Access A&M Data Base
Steel Making
2

8000

7000

回数

5000
MOL
BACKS
SPUTY
CHART
AMDIS

4000

Universities

2000

３ｍ

Micro
Wave

6000

3000

1000

0

H12年度

H13年度

H14年度

H15年度

H16年度

H17年度

Pig Iron

FusionCommunities
ITER
Laser

FIREX target

Solar-B &LHD

NIFS

Industries

Institutes andAcademia• National Astronomical Observatory• National Institute for Fusion Science• Institute for Molecular Science• National Institute for Basic Biology• National Institute for Physiological
Sciences

Ceramics

Nano Science23/25

6. Overview of Review Process
6.1 Structure of Review Process on NIFS Activities
Reviewing Organizations

Director - General

Inter-Operation Administrative Organization

Adviser-23 NON-NIFS committees-Reviews for research results-10 NON-NIFS committees-11 NIFS committees-Discusses important
administrative issues

DeputyDirector - General-28 Non-NIFS committees-18 NIFS committees-Examines plans andadministrative matters aboutcollaborative research.

Exploratory Committee for
Mid-term Plan andPeer Review

PR OfficeOffi
Research
Information Office

Fusion Science
Archives

E
Executive
ti M
Meetingtif Research
for
R
h Di
Directorst
Nuclear Fusion Research
Collaborative ResearchCommittee

LHD Collaborative
Research Committee

Bilateral Collaborative
Research Committee

Review Committee for Research and
Job Planning

Nuclear Fusion Network（Nuclear Fusion Science, Fusion Reactor Engineering, Plasma Science）

Dept. of LHD Dept. of Sim.
Project
Science*b-16

IndividualCenters

DETS *

Dept. of
Administration

Department of Engineering and Technical Services

24/25

6.2 Review System and Process of NIFS
１．Third-Party Review① Review as the National Institutes of Natural Sciences (annually)② Review by the Council for Science and Technology Policy (annually)

２．Peer Review and other reviews① Review by the External Peer Review Committee under the Administrative Council in the National
Institute for Fusion Science・ Large Helical Device (LHD) Research (2004)
・ Simulation Science (2004)
・ Collaboration Research & Joint Activity (2005)
・ Fusion Engineering Research Center (2005)
・ Safety and Environmental Research Center (2005)
・ International Collaboration Activities (2006)
・ Coordination Research Center (2006)
・ Department of Engineering and Technical Services (2006)
・ Large Helical Device (LHD) Research (2007)
・ Simulation Science (2007)
・ Bilateral Collaboration Research (2007-2008)
・ Special Review Committee (2008)② Other Review
・ Reviews by the special advisers for the National Institute for Fusion Science (2004)
・ Reviews by the Cryogenic Association of Japan (2005)
・ Reviews by the Internal Review Committee for Research and Job Planning (annually)③ Review made by the nuclear fusion research workgroup within the Science and Technology
Council・The report submitted on January 8th 2003 by the nuclear fusion research workgroup within the Special
Committee for Basic Problems, Science and Technology Subcommittee, Science and Technology
Council, was checked and reviewed for the promotion of the future nuclear fusion research (2006)

25/25

b-17

3-2 Development of Net-Current Free Heliotron Plasmasin Large Helical Device

Development of Net-Current Free
Heliotron Plasmasin Large Helical Device

A. Komorifor LHD Experimental Group
National Institute for Fusion Science
Toki, Japan
1/15

Outline1. High ion temperature 5.2 keV at ne = 1.61019 m-3
accompanied by Impurity hole
2. High density ne (0) = 1.21021m-3 at B = 2.5 Twith Internal Diffusion Barrier (IDB)
in Helical Divertor_
3. High beta <> = 5.1 %, <> > 4.5 % for > 100E
4. Steady state
5. Summary

2/15

b-18

New perpendicular NBI much improves
ion transport study- High-power NBI of 23 MW in total  4 beam lines of NBI= 3 tangential + 1 perpendicular ( + 1perpendicular in 2010)
Tangential beams• 16 MW in total, ENBI = 180 keVwith negative-ion sources• Primarily electron heating• Less fraction of trapped particles

180keV-tangential
NB injector

40keV-perpendicular
NB injector

Perpendicular beam
• 7 MW
MW, ENBI = 40keV
with positive-ion sources• Ion heating (Ti(0) = 5.2 keV)• works as a diagnostic beam for
CXRS (Ti, V, V, Er)• Confinement of trapped particles
secured by geometrical optimization

3/15

High Ti plasma realized
by upgrade of ion heating power_
Ti (0) reaches 5.2 keV at ne = 1.61019m-3

 Heating Power N-NBI: 12 MW, P-NBI: 3.5 MW for high-Ti
 Ti > Te in core and Ti < Te in edge
4/15

b-19

Improvement of ion heat transport
6

100

5

2

 (m /s))

4
3

Exp.

10
Exp.

i

Ti (keV)

t=2.06st=2.35st=2.06st=2.35s2
NC Calc.

1

NC Calc.

0
3.6

3.8

4.0

4.2
R ((m))

4.4

1

4.6

0

0.2

0.4

0.6

0.8

1.0



Reduction of i_exp appears in the core
 Ion root (Er < 0) in core and Electron root (Er >0) in edge-> core transport is improved to NC level
5/15

Carbon impurity is expelled due to outward
convection : Impurity Hole2.5
t=1.25s
ncvi (1019 m--3)

1.5
t=1.65s0.5

t=1.25s

0.3

0.04
0.03

0.2
0.1

0
3.6 3.8 4.0 4.2 4.4 4.6 4.8
R (m)

0.05

0.02

t=1.65s

nccvi (1019 m-3)

ne (1019m-33)

2.0

1.0

0.06

0.4

0.01

0
0
3.6 3.8 4.0 4.2 4.4 4.6 4.8
R (m) More hollow as the ion temperature gradient is increased
 Steep Ti gradient  Extremely hollow carbon profile “impurity hole”,

which is quite different electron density profile.
 Contradicting NC prediction  suggests anomalous convection

6/15

b-20

 of 5.1 % has been achieved and  of 4.5 %has been maintained in steady state
3-D equilibrium calculated by HINT

5

<> (%
%)

4
3
2
1
0
0

<> > 3.5 %50

duration

100

/

150

E

 Beta limit
 Transport in the ergodic layer
 Change of magnetic topology,e.g., magnetic island dynamics
Effect of stochasiticity has been investigated in detail
7/15

Operational Regime of high-Standard
Scenario

Magnetic axis position is a key
parameter for high-beta Standard Scenario(broad pressure profile)- restrict of the plasma outward shift
for keeping good heating efficiency
in low-field increase plasma aspect ratio <> = 5.1 %, 0 ~ 10 %
 IDB Scenario(peaked pressure profile)- overcome the core density
collapse <> = 2 %, 0 ~ 10 %IDB
Scenario

Ap = 6.6(2005~)Ap = 6.3(2004)Ap = 5.8(~2003)

Real time control of Bv
 Much higher beta with thisoperational window extension of operational regime

8/15

b-21

Interaction between Alfvén eigenmodes andenergetic-particles in LHD
TAE-induced fast-ion loss measurementwith scintillator probe (SLIP)
Analysis in collaboration
with AE3D code

Understanding of
RSAE freq. sweepingwith MHD theory

Impact of Alfvén eigemodes on
GAM

Phase spacestructure analysis
of TAE-induced
fast-ion transport
9/15

Achievements of High Density High Pressure
Discharges with Internal Diffusion Barrier Maximum ne(0) exceeds 1×1021 m-3
Maximum P(0) =130 kPa• Pressure rise is limited byCore Density Collapse (CDC)• CDC mitigated by elongation
 P(0) = 150 kPa
 IDB width widens as the preset magnetic
axis is put outward and IDB foot reaches
to LCFS with Rax= 4.0 m

LCFS

IDB foot
shifted axis

max. ne(0) optimized

max. P(0)IDB formation

10/15

b-22

Diffusion Coefficient kept at tolerable level
under large density gradient due to IDB
Relationship between time
evolution and gradient ofdensity profilespCore plasma• a (pressure rise): dne/dρ increases
with IDB formation, D≈0.05 m2/s
• b (maximum pressure): flux
increase without dne/dρ change• c (pressure decline): dne/dρ
decrease with density decay,D≈0.05 m2/s

Mantle plasma• A (IDB formation period): Can notreach large dne/dρduring high flux
IDB phase, D≈0.43 m2/s
• (after IDB disappearance): merge
into c, D≈0.05 m2/s
Thermal transport is unaffected byparticle transport

11/15

Transport in ergodic layer is a key
in high-performance high density plasma
LC/mreff (m) 105 104 103 102 101 100 200
0.70

Te/eV
100

0

Core plasma is surroundedbyy ergodicglayer
y byy stretch
and fold of magnetic islands

Edge surfaceylayers0.65
Stochastic
region0.60
CIII/ne exp.
CV/ne exp.

3-D edge transport code : EMC3-EIRENE Impuritypy screening
g in stochastic regiongby friction with bulk plasma flow
 Retention of impurities via shot flux tubein edge surface layer Remarkable reduction of impurity
contamination in high density operation

Emission Exp
p. (a.u.)

InboardOutboard

CIII /ne Sim.
CV /ne Sim.

102

100

10-1

0

2 _ 4
6
ne (1019 m-3)

8

101

Emission Sim
m. (10-19 W m3)

Inboard

12/15

b-23

Control of heat load on divertor plate isa major key for steady state operation
Critical PRF=0.65 MW : Penetration of metal impurities from deposited layer
on divertor plate  can be simulated by small Fe pellet
2

plPulse length (s)1

PRF (MW)ne (1019 m-3)0

Divertor
Temp. (K)

 =- log(1-P

Te0 (keV)

Tdiv (K)before replacing

400

ht

RFcr

/P )
RF

Before
After

3

10

after replacing

200

2

0

10
0

200

400
600
Time (sec)

800

0.5
1.0
1.5
Averaged RF Power (MW)PRF = 1.1 MW (PICH = 1 MW, PECH = 0.1 MW)
 Divertor plates with significant temperature increase replaced by ones with better heat conductivity
 critical PRF is mitigated Mode-conversion heating not to produce energetic ions

13/15

Nearest Future Plan
1. Upgrade of heating capability
NBI
ICH
ECH

5th beam line 7 MW, 60 keV
3 MW steady state
1 MW steady state

2. Closed helical divertor
3. Deuterium• Identification and documentation of isotope effect• Upgrade of NBI (32 MW in total)
4. Reactor design study
FFHR :
Force-Free Helical Reactor
14/15

b-24

Summary
1. High ion temperature 5.2 keV at ne = 1.61019 m-3
with confinement improvement
2 High beta <> = 5.1
51%
4 5 % for > 100E2.
%, <> > 4.5
3. High density ne (0) = 1.21021m-3 at B = 2.5 Twith Internal Diffusion Barrier (IDB)
4. Steady state 1MW for 800 s
5. Near-term
5Nt
upgraded packagekclosed helical divertor, heating capability, deuterium
6. 3-D effect inspiring new advanced physics model andtheory which are to be validated in LHD experiment
15/15

b-25

3-3 Simulation Science in NIFS

Simulation Science in NIFS
N.Nakajima and DSS members

OutlineI. Purposes
II 3 projects
II.

LHD and Magnetic Confinement Simulation Project
Laser Fusion Simulation Project
Plasma Complexity Simulation Project

III. Future plan
IV. Summary
Purposes
To clarify and systematize the confinement physics of fusion plasmas andto promote the basic science based on the simulations, by developing
predictive simulation codes like a Numerical Test Reactor based onhierarchy-renormalized model, leading to establishing simulation science

0/21

3 projects
I. LHD and Magnetic Confinement Simulation Project
Hierarchy-extendedysimulation
Core plasma fluid model group
Core plasma kinetic model group
Peripheral plasma model group
Hierarchy-integrated simulation

Hierarchy-renormalized simulation+
Reactor design
Numerical Test Reactor Project

II. Laser Fusion Simulation Project
related to FIREX project at Osaka University

III.
III Plasma Complexity Simulation Project
Magnetic reconnection
Plasma material interaction

1/21

b-26

LHD and Magnetic Confinement Simulation Project
Purpose： To exploit and understand the physics on cross-hierarchy interactions ofcompound physics processes by developing a predictive hierarchy-renormalized simulation
model under the domestic and international collaborations, leading to an
Numerical Test Reactor (simulation code) predicting overall behaviors of fusion plasmas
Hierarchy-renormalized simulation
Hierarchy-integrated simulation To predict the whole temporal behaviors ofexperimentally observable macroscopic quantities (M.Sato, A.Fukuyama, Y.Nakamura,
S.Murakami, K-Y,Watanabe, M.Yokoyama, S.Toda, Y.Funaba, N.Nakajima)

Knowledge (theoretical model, database, modules) for improving predictability
Hierarchy
Hierarchy-extended
extended simulation To exploit and understand the physics on
cross-hierarchy interactions of compound physics processes• core plasma fluid model group : (Y.Todo, H.Miura, R.Ishizaki, A.Ishizawa, A.Ito, M.Sato,
K.Uzawa, N.Nakajima)• core plasma kinetic model group : (T-H.Watanabe, H.Sugama)• peripheral plasma model group : (Y.Tomita, G.Kawamura, M.Kobayashi, A.Takayama,
D.Kato, K,Ohya, D.Tskhakaya, A.Kirschner)

2/21

Hierarchy-extended simulation (Core plasma fluid model group)• MHD
I. MHD Infrastructural code for Plasma Simulation(MIPS) (Y.Todo,N.Nakajima)common source for collaborators (in this FY)
II High precision MHD simulation in LHD
II.
(MINOS) (H.Miura)• Extended-MHD
I. Pellet dynamics (CAP) (R.Ishizaki)
II. Long time AE simulation in LHD (MEGA) (Y.Todo)

Perturbed pressure profile with multiple
ballooning modes (χ|| reduces them)Comparison of
MIPS and
CAS3D results ofballooning modes
in LHD
Plasmoid drifts to lower field side in LHD.
Alfvén eigenmode burst in
LHD(#47645) was foundwith reduced simulation
code.
3/21

b-27

Hierarchy-extended simulation (Core plasma fluid model group)• Extended-MHD (Two-fluid model)
I. Two-fluid equilibrium with flows and ion
Larmor radius effects (A.Ito)
II. Turbulent transport in externally heated plasma(A(A.Ishizawa)
I hi)• Full implicit algorithm
Development of full implicit method by extending
2D spectral finite element code (SEL) to 3D(HiFi) (M.Sato, A.Glasser)
Singularity at the boundary is regularized due tothe ion FLR effects

Radial profiles of χi and zonal flow.
χi increases around magnetic island(r/a=0.6), which partially comes frommacro-scale convective cell flow.
2D static condensation subroutine
h b
d and
d extended
t d d
has
been iimproved
to 3D subroutine.

Isosurfaces of each quantity do not coincidebecause of the flow and the two-fluid effects

4/21

Hierarchy-extended simulation (Core plasma kinetic model group) Progresses in gyrokinetic theory and simulations for toroidal
plasmas (T.-H.Watanabe, H.Sugama) Zonal flow enhancement and turbulent transport reduction in helicalsystemst
isi confirmedfidb
by GKV simulations.
i l ti(Watanabe, et al., PRL 2008)

 Zonal-flow response in case with equilibrium radial electric field (Er) istheoretically derived. (Sugama et al., invited talk@APS/DPP 2008)
 GKV code is extended for poloidally-global model for application to thezonal-flow response analysis in case with Er.
((Watanabe et al., oral presentation@ICPP2008)p@) Enhanced zonal-flow response isfound in a single-helicity case.
(Watanabe, et al., 22nd IAEA FEC)

5/21

b-28

Hierarchy-extended simulation (Core plasma kinetic model group) Progresses in gyrokinetic theory and simulations for toroidal
plasmas (T.-H.Watanabe, H.Sugama) [continued]
Radial drift ofhelically‐trapped
particles

vdr

Orbit of helically‐trapped
particles modified by Er

vEXB
E

Er
B
Flux
surface

New GKV simulations for zonal-flowenhancement by equilibrium Er.

Theoretical model for zonal-flow
response in case with Er.

6/21

Hierarchy-extended simulation (Peripheral plasma model group)
1D fluid model of plasma profiles in the LHD divertor leg(G. Kawamura, Y.Tomita, M.Kobayashi, D.Tskhakaya)

19-3n (// 10 m )plassma density

0.6

2009
2008

0.5
0.4
0.3

PFW (ERO)

collisional
pre-sheathmagnetic
pre-sheath

CPS(collisional
pre-sheath)

0.7

Debye sheathboundary layer plasma

objectivemodeling of boundary plasma between
・modeling
SOL and divertor plate andPFW (Plasma-Facing Wall) by fluid model
resultsgcollision-less region

core plasma

s=L

0.2
0 0.5 1 1.5 2 2.5 3
Distance along field line from SOL s (m)

PFW
H, H2

・CPS: collision with neutral → dn/ds < 0・collision-less plasma → dTi/ds < 0 → dn/ds > 0
reduction of heat load to divertor plate

b-29

SOL

s=0

C0

divertor

density peak

s=L

7/21

Hierarchy-integrated simulation• Development of a core transport code in 3D configuration :TASK3D(A.Fukuyama, Y.Nakamura, M.Sato, S.Murakami, K.-Y.Watanabe, N.Nakajima)

Module structure applicable to
3D configuration
TASK3D:common source for collaborators (in this FY)

8/21

Hierarchy-integrated simulation•Analysis of LHD plasmas by TASK3D
MHD stability limit beta profile
VMEC

Stability

TR•Development of GUI application

The achievable beta
value is expectedbeyond 6% under theassumption that theideal interchange
modes with m ≤ 4 limit
the pressure gradient.
(M.Sato,K.-Y.Watanabe,
Y.Nakamura)

Verification of NBI heating module (TEST)
VMEC

FIT3D

TR

ER

DCOM/NNW

Comparison of energy
confinement times
obtained by TASK3D
with the scalings.
(M.Sato, S.Murakami,
K.-Y.Watanabe)b-30

The GUI application is equipped with・selecting modules,
・setting input parameters and files,
・submitting job,for easy use of TASK3D.
(M.Sato, K.-Y.Watanabe)
available (in this FY)

9/21

Targets in this mid-term plan
Hierarchy-extended simulation（Core plasma fluid model group）
 to analyze AE-induced excitation of GAM
 to clarify the roles of high wave number pressure-driven modes in LHD
 to clarify the plasmoid motion in LHD
 to clarify interactions between macro-MHD instability and micro-turbulence to analyze two-fluid equilibrium and linear stability of LHD plasmas with flows
Hierarchy-extended simulation（Core plasma kinetic model group）
 to analyze influence of macro-scale Er on zonal flow response in helical systems
 to extend GKV code for more realistic configuration
 to analyze ETG turbulence and zonal flows in toroidal plasmas
Hierarchy-extended simulation（Peripheral plasma group）
 to
t completel t 1D flfluid
id ttransportt modeld l iinterconnectingtti SOL andd PFW to develop a 3D fluid transport model of plasma and neutral in collisional pre-sheath to develop a PIC transport model in magnetic pre-sheath and Debye sheath
Hierarchy-integrated simulation
 to intensively check of TASK3D modules by applying TASK3D to experimental data to implement impurity module and DD reaction model into TASK3D
 to formulate system of transport equations with plasma flow in 3D configuration

10/21

Laser Fusion Simulation Project
Purpose：To totally clarify physics of the Fast
Ignition and to design targets for
FIREX (FastRealization(F t Ignition
I iti
R li tiEXperiment) project at Osaka Univ.
by FI3 integrated simulations undertight collaborations among Osaka
Univ., Setsunan Univ., Kyusyu
Univ., and KPSI JAEA.

Organization of Collaborations
Radiation-hydro code : Osaka Univ.
Relativistic PIC code : NIFS and KPSI JAEA
Fokker-Planck code : Osaka Univ. and Kyusyu Univ.
Level up of FI3 by introducing hybrid code : Setsunan Univ.
To develop collision model : NIFS, Osaka Univ., and Setsunan Univ.

b-31

11/21

Laser Fusion Simulation Project(H.Sakagami) A pre-pulse of the heating laser generates the
preformed plasma and its scale length is alsoy the ppre-pulse.
pdetermined by
 The preformed plasma with a longer scale length
can maintain the bulk electron density nb at a lower
level, so that the core heating is sustained for alonger time. (electron beam intensity ∝ nb-1/2 ) However, characteristics of the pre-pulse are not
Au coneeasily controllable.
 Thus, we propose
to coat the inner surface of Au cone with low densityy foam,p ppreventing the preformed plasma from being snowplowed to extremely highdensity at the laser front of the main pulse.
Low density foam
Au
Main pulse

Pre-pulse

12/21

Preformed plasma

Laser Fusion Simulation Project(H.Sakagami, T.Johzaki, H.Nagatomo) By analyzing the core heating characteristics for various foam parameters with FI3
simulations, it is found that there are an optimum density of the foam and anecessary minimum thickness of the coating.
 In the case of low density foam, the heating laser can relativistically penetrate into thefoam plasma and directly interact with the extreme overdense Au plasma.
 With high density foam, electrons in the foam plasma are snowplowed to such densitythat the fast electron beam intensity can be substantially repressed at a low level.

 In the case of 20ncr with 60m thickness foam, the core electron can reach 2.6keV.

13/21

b-32

Targets in this mid-term plan
To perform basic evaluation of FIREX target through following
steps, under the collaborations with Osaka Univ., Setsunan Univ.,
Kyusyu Univ. and KPSI JAEA.
1. To develop a Langevin-type collision model based on empirical law,and to introduce it into 1D relativistic particle code
2. To interconnect 2D relativistic particle code into FI3
3. Analysis of fast electron transport by using hybrid code

To realistically analyze FIREX experimental results in Osaka Univ.,ththroughh ffollowing
ll i stepst
1. To enlarge the scale of FI3 simulations including 2D relativistic particle code
2. To expand the empirical collision model into 2D relativistic particle code
3. Level up of FI3 by introducing the hybrid code

14/21

Plasma Complexity Simulation Project
Purposes• To clarify the magnetic reconnection phenomena, which are controlled by various physics
from micro to macro‐scale, in solar and magnetosphere plasma and fusion plasma.
• To clarifyy the pplasma‐material interaction in compoundpphysicsp ysystem.
yMethod• To develop and use hierarchy‐renormalized simulation model with domain‐decomposition
method.

Members• R.Horiuchi, S.Ishiguro, M.Skoric, M.Den, H.Nakamura, H.Ohtani, S.Usami
Collaboration with universities and institutes of NINS• In solar and magnetosphere plasma; National Astronomical Observatory of Japan (NAOJ),
Earth Simulator (ES), Kyusyu univ., Chiba univ.
• In plasma‐material interaction; Institute for Molecular Science (IMS), and Shinsyu, Yokohama
National, Saitama, Tokyo, Nagoya, and Konan universities.

15/21

b-33

Magnetic reconnection phenomena•••

Search of magnetic reconnection points insubstorm process by MHD model (Fig.1)
Clarification of generation mechanism of
anomalous resistivity due to instabilities byusing EM PIC simulation (Fig.2)
Development and verification of hierarchy‐
renormalized simulation model based on thedomain‐decomposition method with MHD
model and PIC (Fig.3)

Reconnection point(X point)z+－ + +－－ － +
x

Short kink mode (tce=5370)(T.Moritaka,
R.Horiuchi))Earthlong kink mode (tce=8788)

O point

Vx

MHD



PIC

MHD

Fig.1 Magnetic
topology during thesubstorm (signs of Bx
and Bz) in the noon‐
midnight meridian ofmagnetosphere(M.Den,T.Tanaka)(S.Usami,
H.Ohtani,
R Horiuchi
R.Horiuchi,
M.Den)

yFig.2 Generation of anomalous resistivity by two kinkinstabilities with different wave numbers.

Fig.3 Numerical verification of hierarchy‐normalized model by using
1D Alfven wave propagation (top), and plasma inflow from MHD
domain to PIC domain (bottom).

16/21

Plasma-material interaction•••

Fig.1 snapshot of
C2H2 generation with
the incident energyof 5eV (left). The
C2H2 is mainly
produced fromgraphite armchair

Generation mechanism of C2H2 from thechemical spattering on a graphite surface isclarified by using MD simulation (Fig.1)
Blob simulation byy 3D PIC code (Fig.2)( g )Development and verification of multi‐
hierarchy simulation model based on thecourse projection method (Fig.3)(1 1 ‐2 0) surfaces(right (a),(b),(c)).

(A.Ito,H.Nakamura)(A.M.Maluckov, S.Ishiguro,
M.M.Skoric)

Fig.2 Isosurface and contour plot of ion density.

(S.Ishiguro)
Fig.3 Schematic picture of course projection method(left) and time evolution of total energy by PIC code (red)and course projection method (black) (right)

17/21

b-34

Targets in this mid-term plan
Magnetic reconnection phenomena
Verification and improvement of hierarchy‐renormalized simulation model, and check of theapplicability to magnetic reconnection (left fig.)
Consideration of method interconnecting micro model with macro model in geo‐tailgeo tail
Application to fusion plasma (reconnection with strong longitudinal magnetic field)
Plasma‐material interaction phenomena
Expansion of MD of chemical sputtering to large scale (1003 nm3) material in hierarchic graphite
structures by comparison with Monte Carlo ACAT simulation (right fig.).
Introduction of Coulomb collision into blob transport simulation and clarification of blob transportphenomena.
Improvement of the multi‐hierarchy simulation model based on the course projection method

Driving Force

Present material

Left: application ofhierarchy‐renormalized
model based on thedomain‐decomposition
methodMHD
interface
PIC
interface
MHD

Next target

Right: polycrystalline
graphite as next target of
MD simulation.

Driving Force

18/21

Future plan : Road map of LHD and magnetic confinement simulation project
Hierarchy-integrated simulation To Introduce knowledge from the Hierarchy-extended simulations
The 1st generation
The 2nd generation

To develop measurement and control modules

To complete Numerical Test Reactor

The 3rd generation(Numerical Test Reactor)

To develop and check basic
modules of TASK3D, byapplying to LHD experiments+

Reactor design

Hierarchy-renormalized modelTransient dynamics, Turbulent transport coefficients,
Boundary condition.
To develop various Extended-MHD models.
To extend local turbulent transport of ions or electrons.
electrons
To develop basic peripheral plasma model

Numerical Test
Reactor Project

To complete comprehensive core fluid plasma,core kinetic plasma,
plasma and peripheral plasma
models.

The 3rd generation

The 2nd generation
The 1st generation

To develop comprehensive core fluid plasma model.
To develop global turbulent transport of ions or electrons.
Hierarchy-extended simulation To Extend peripheral plasma model.
New plasma simulator

08 JFY 10

12

14

16

b-35

18

20
13

22 19/21

Numerical Test Reactor Project
To create a fusion energy reactor in a virtual space (computer) in order to optimize
properties on physics and engineering, and economical aspects
Application ofimaging science

Hierarchy-extended simulation for precise physics

Super computer
77TF (2009)
315TF (2012)

Introduction of physics knowledge to improve predictability
Input
heat &
particles

outputheat, particles

control ofheat, particles

magnetic
structure

α particles

neutron

Hierarchy-integrated simulation: to predict thewhole response of macro quantities (NTR)

Verification by LHD
data base on physics
and engineering
R&D of system& materials
Modeling
Reactor design：technological,
economical,
ecological, &safetycompatibility.
Evaluation ofefficiency
Change in condition

feedback
Optimization of helical reactor with integration of high performance plasma and structure components &systemSummarySimulation researches based on collaborations are being functionallypromoted by constructing 3 projects and working groups.
yp
g large-scalegg y enlarged
g byy usingg fullperforming
simulations highlyBysystem of the new plasma simulator, we will try to obtain new
knowledge of cross-hierarchy interactions and to improvepredictability of hierarchy-renormalized simulations.
In the 2nd mid-term plan, we will proceed to clarify and systematize
the confinement physics of fusion plasmas under project researches
based on collaborations with road map, and aim at constructing
Numerical Test Reactor with predictability (Numerical Test Reactor
Project), and also promote the basic science based on thesimulations under the coordination researches among various fields.
Above plan will finally lead to establishing simulation science, in thecenter of which fusion research sets.

21/21

b-36

3-4 Activities of The Research Coordination Center

Activities of
The Research Coordination Center(RCC)

Presented byMotoyasu Sato

1/42

The Research Coordination Center (RCC)• Establishment: in April, 2004.
• Philosophy:
The researchers would serve for thecooperation work on the bases of the big devices
such as LHD and it’s related science andtechnologies by holding their own high researchcapabilities.
The cooperation would return to NIFS with
innovation, we call it “the Boomerang Effect”.
It distinguishes the NIFS’s RCC to thecooperation systems in the other universities.
2 /42

b-37

Modified Organizations of RCC
Up to 2007

From 2008

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3/42

Activities of Research Coordination Center
Functions: Co-operations for innovation to science and technologies
Growing Access A&M Data Base
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FusionCommunities
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Laser

NIFS

Industries

Institutes andAcademia• National Astronomical Observatory• Institute for Molecular Science• National Institute for Basic Biology,• National Institute for Physiological
Sciences• National Institute for Fusion Science
Solar-B &LHD

Ceramics

Nano Science

b-38

4/42

Topics in the Two Years• Activities of Atomic & Molecular andEdge Plasma Data Department
Y.Hirooka, I Murakami, H.Sakaue, D.Kato• Division of Industrial-Academic Research C.
Industry Cooperation Group
Basic Innovation Science &Technology G.
M.Sato, S.Takayama, M. Tanaka• Division of Science Communication
Fusion Kid’s Energy Museum
N. Inoue,
5/42

The New
Atomic / Molecular andEdge Plasma Data Group (division)•The physics on core plasma has given the very promising experimental results forthe fusion world. The fusion technology has been accumulated the knowledge ofmaterials for the fusion.
•Many basic ideas has been proposed for the rector design including diverters andfirst wall etc.
•So to say,it is identical to the ages in 1950~70 in proposing many ideas for plasma
confinements, such as such mirrors, Z-pinches, Tokomak and Heliotron,etc.
•Now, we are helming to the research to serve more idea and data for develop thereactor systems. It will be difficult to treat walls as an obstacles affecting to plasma or
to see the plasma as the the enemy of materials.
•We are going to investigate the plasma from the view point of walls to accept theradiation of neutrons, protons, alpha particles and high heat flux.

•We are now knocking the next door to the fusion world.
6 /42

b-39

Roadmap to resolve PWI-issues
in fusion reactors
By Y. Hirooka
Boundaryr control concepts development
Revaluation of existing core-to-edge plasma data
Enhancement of PWI+A&M research

Applied materials to boundaryr control
Optimization of hydrogen and helium retention characteristics
Fluid dynamics modeling of liquid metals and molten salts

Proof-of-principle exps. on boundaryr control concepts
PoP exps. in a divertor simulator
PoP exps. in long-pulse confinement devices (LHD, QUEST)
Extrapolated simulation to numerical fusion reactors

7/42

PWI-issues in steady state fusion reactors
Tokamaks•••••

High heat/particle fluxes to PFCs
Erosion and core contamination
Disruptions
Giant ELMs
H-mode (High-T mode)in tokamaks––•

power threshold transition
led by passive wall pumping

S-mode in TFTR–

led by passive wall pumping

Stellarators/Heliotrons
•
•
•
•
•
•

High heat/particle fluxes to PFCs
Erosion and core contamination
No disruption
No giant ELMs observed so far
H-mode in W-AS7
Superdense mode in LHD•

Large SOL surface area for thesame plasma volume––

led by reduced edge density by LID

more PWI-susceptive

A need for the control over PWIs in both tokamak and stellarator/heliotron reactors
to sustain high-confinement operations at “steady state”.

8/42

b-40

PWIs in magnetic fusion devices
1. Materials erosion,,C  W   ne C s , E  kTe , where C s =Erosion depth of 10cm/yr. estimated for the C-divertor in ITER

2. Tritium inventory,k (Ti + Te )m

  n C s (Te ), E  kTe

C  W

Tritium inventory of a few kg/yr. estimated for the C-divertor in ITER e

3. High-heat flux removal,
Heat fluxes of ~20MW/m2 estimated for ITER

W , C on Cu

  ne C s (Te ), E  kTe

Suppression of PWIs by materials choice
Further suppression of PWIs by edge-plasma control)Boundary control
Choice is either the reduction of ne or Te ?

9/42

Application of Li-MS-PFC to a spherical tokamak

Shot#505891-#505929

Li-ON(Te~20eV)

Li-OFF(Te~7eV)Supershots in TFTR

10/42

b-41

Moving-surface plasma-facing components(MS-PFC concepts)
Moving-solid surface
Fusion device

Environment

Vacuum wall

Plasma flow

Moving-liquid surface

Low vacuum
enclosure

Tritium
recovery

Heat
Getterremoval deposition

Moving direction

PumpingsystemAfter Y. Hirooka et al. 17th SOFE(1997)

After M. Abdou e t al., Fusion Eng. Des. 54(2001)181.

.

11/42

Application to a spherical tokamak & LHD*oundary control devices,CL

H spectrosccopy

Rotating drum
Chain
drive

Water
cooling
Power tothe evaporator
Ti,Li evaporator

R=0.3m, a=0.2m, B=0.25T
50kW RF current drive

After Y. Nagayama SOFT2008(8.2GHz kylstron)

12/42

b-42

Application of MS-PFC to a spherical tokamak
Li-gettering ON

Li-gettering OFF#505908 w/Ha #!

#505910 w/Ha #!

13/42

Plasma diagnostics by using impurity ions
By Izumi Murakami

Light Ions to Heavy Ions•

It is important to understand behavior of impurity ions in peripheral region forplasma transport and plasma control problems. Atomic processes in plasma
play an important role to understand these problems and plasma diagnostics.
We study atomic processes in plasma and plasma spectroscopy.

•

We have developed collisional-radiative (CR) models for impurity ions, such as Fe
ions, Ne ions, O ions, and C ions and used these CR model to obtain electron
temperature and density dependences of spectral line intensities. Many kinds ofatomic collision processes are included in CR models. By comparing spectral line
intensity ratios measured spectroscopically and ratios obtained from CR models, we
can estimate plasma parameters.

•

We include recombination processes and inner-shell ionization process in the CR
model. These processes were not included previously.

14/42

b-43

Plasma diagnostics by using OV and OIV lines

We estimate contribution of innner-shellionization from OIV ion (red) and this can
explain the measured ratio, with assuming
electron temperature Te ~ 30-50eV and theion density ratio n(OIV)/n(OV)~2-5, which(a) Line intensity ratio I(OV 76nm/OV
63nm) for NBI-heated LHD plasma is
about 2.23.+#15078)(b) Theoretical intensity ratio for ionizing
plasma (red) and recombinig plasma(green) or equilibrium plasma (blue)
cannot explain the measured ratio.

is larger than the equilibrium plasma ratio
0.22-0.042.
This indicates NBI-heated LHD plasma is
not in ionizing equilibrium.

15/42

  

Plasma diagnostics by C V

CVI 33.734(
Resonance line

CV 40.27(
Resonance lineCV 40.73(
Intercombination line

The collisional-radiative model for CV ion gives
electron temperature dependence of each spectral line
intenstiy.
Electron temperature is estimated by using intensity
ratio of the CV intercombination line to the CV
resonance line for NBI-heated LHD plasmas.
Comparing with the electron temperature distribution
measured by Thompson scattering, location of CV
emitting region can be estimated at around ~1. Thismeans He-like Carbon exist in peripheral region.

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16/42

Research on non equilibrium plasma by using LHD and
the Solar obserbing satellite “HINODE”
•
•

•
•

•

Collaboration with National Astronomical
Observatory and Univ. of Electrocommunications.
To examine non-equilibrium plasmas byspectroscopy, we have developed a collisionalradiative (CR) model for Fe ions, evaluatedatomic data for Fe ions, observed the solar
plasma by HINODE EIS, measured LHD
plasma, atomic collision experiments withcompact EBIT.
We examined Fe ion spectra from LHD
plasmas and analysed with using the CR
model.
Using density dependence of Fe XIII line
intensity ratios obtained by the CR model, we
estimated the electron density distribution of
the sun active region.
We are going to develop a time-dependent CRmodel and combine with a solar flare model
code to examine the mechanism of coronalheating by using Fe ion spectral lines. Thismodel will be able to use for LHD plasma
diagnostics.

EUV spectrum of LHD plasmaand our model

Electron density distribution obtained by 3 pairs of
Fe XIII lines for the sun active region

17/42

Tritium for Fusion
Scientific Research in Priority Areas (2007-2011)by Daiji Kato
• Tritium inventory and recycling in reactors are important
issues of study in safety and economic aspects of fusion
reactors.
• Material and plasma behaviors (physics) under tritiumrich condition are little understood.
• Theoretical models and integrated simulation code for
global T inventory and recycling are being developed
through collaboration of plasma, material andatomic/molecular physicists.

18/42

b-45

TOPICS 1: Excited atomic hydrogen at metal surfaces
Excited hydrogen plays characteristic roles (larger probabilities of photon emission, ionization andcharge exchange) in edge plasmas. Highly polarized level population via electron capture at metals
surfaces was predicted in this study. This finding is a useful knowledge for precise spectroscopic
measurements of hydrogen-recycling in plasma-wall interaction.
Mechanisms for excited state creation

D. Kato, T. Kenmotsu, K. Ohya and T. Tanabe, 18 th PSI (Toledo), J. Nucl. Mater. accepted.

Development of theoreticalmethod to study electronicinteraction of hydrogen isotopes
and metal surfaces.

H+

e/H+

reflection
h

e

H*

Knock offby plasma ionssputtering

Upper figure: Electrostatic
potential energy surface ofelectron near Mo surface.
Hydrogen nucleus is located at
the origin, 10 a.u. above from Mo
surface. Cylindrical coordinates
are used.
1 au length = 1 Bohr radius.
1 au energy = 27.21 eV.
Development of first principle
method to study excited level
population of reflected hydrogenatoms at metals surfaces.

electron transfer

Fermi lev elsurface

atomic lev els

Doppler-Fermi-Dirac
distribution

Lower figure: Highly polarizedoccupation probabilities of excitedlevels of deuterium atoms reflected
at a Mo surface with incident
energies of 5 - 25 keV.

19/42

Isotopic effects of atomic collisions
Electron transfer in D+ + HD and D2 / H+ + H2
Change molecular assisted
recombination (MAR) rates ofedge plasmas

Isotopic effects reduce crosssection by more than 50 % !

Kusakabe et al., Phys. Rev. A 70, 052710 (2004).

b-46

20/42

TOPICS 2: Hydrogen trapping in bulk tungsten
Electronic interaction of hydrogen with vacancies are studied by means of the first principle molecular
dynamics. Multiple-hydrogen trapping by vacancies and super-abundant vacancy creation underhydrogen-rich condition were predicted in this study.
D. Kato, H. Iwakiri and K. Morishita, 14 th ICPP (Fukuoka) oral selected topics, J. Plasma Fusion Research Ser. accepted.
Electron density distribution withinterstitial H (tetrahedral-site) in W

Site proj ected density of states(DOS) for each partial w av e

matrixElectron density distribution with VH(octahedral-site) in W. V stands formono-vacancy.

energy / Hbinding energy

mono-v acancy (V)Electron density distribution
with H 2 at the center of monovacancy in W

Image of VH 3 cluster in W.
Red: H, Blue: W.

21/42

EUV spectroscopy of highly charged iron ionswith a low energy compact EBIT
by Hiroyuki Sakaue
The spectroscopic investigation of highly charged
ions attract attention not only in atomic physics but also
in the diagnostics of nuclear fusion and astrophysicalplasmas.
Y

We measured extreme ultraviolet (EUV) spectra ofhighly charged iron ions (Fe IX - Fe XXIV) in therange of wavelength 100-300  by a new compact
electron beam ion trap (EBIT) which was developed forlow electron energy operation. The electron energy ofthis compact EBIT is controllable from 100 eV to few
keV, therefore it is appropriate for spectroscopic
investigation of the moderately charged ions. A slitless
ﬂat-ﬁeld EUV spectrometer developed exclusively forthis compact EBIT is mounted with it and highsensitivity and high resolution spectroscopic analysis ofhighly charged iron ions become possible. A schematic
drawing of the EBIT and the EUV spectrometer are
shown in Figure 1

DT2
X

235mm

237mm

LN2 tank

Electron Collector

TMP

Grating

CCD

DT3
DT2
DT1







Electron Gun
TMP
compact EBIT
"CoBIT"

Fig.1

b-47

Stray Light Baffle PlatesElectron Beam

EUV Spectrometer

Cross sectional view of compact EBIT
and EUV spectrometer

22/42

Laser Coop.; Temperature control of FIREX target
2D Model for calculation• Heat input to the cone of 0.25nW
can minimize the temperature
distribution in the solid fuel layer.
• The layer uniformity of the FIREX
target would be achieved with thetemperature control.
23/42
1

NODAL SOLUTIONSTEP=1
SUB =1
TIME=1TEMP(AVG)
RSYS=0
SMN =12.00001049
SMX =12.000045776

No Heat input

SEP 26 2008
10:55:09

Heat input of 0.25x10-9 W

12.00001049
12.000011
12.000012
12.000015
12.00002

YZ

12.000025

X

12.00003
MX

12.000035
12.00004

Within 1 K of
Temp. distribution

MN

Integrated Fast Ignition Simulations• FI3(Fast Ignition Integrated Interconnectingcode) project• We found that the fast electron beam intensity
has well scaled as the inverse square root of
the electron density at the LPI region
independent of another parameters.
• We proposed a cone target, of which an innersurface is coated with a low-density foam, tomaintain the fast electron beam. FI3
integrated simulations are performed toestimate core temperatures, and the foam
density and the thickness are optimized.
24/42

b-48

Maximum Core Electron Temperature (keV)– collaboration with Osaka Univ.,
9 Setsunan Univ. and Kyushu Univ.

32

40[μm]
60[μm]

1

70[μm]
80[μm]

Initial Temperature
0
0

10

20
30
Foam Density (nfoam/ncr)

4050

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25/42

Very High pure steel will contribute to make first wall for fusion





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MicrowaveConventional

Blast furnace

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

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

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26/42

b-49

Microwave Steel Making by Motoyasu Sato27 /42Formation of Nano-Domains by
Microscopic Thermal Non-Equilibrium
Generated in High Frequency Microwave H-Field
M. Sato1),
S. Takayama1),
A.Matsubara1),
M. Tanaka1),
Maxim Ignatenko1),
Jun Fukusima1)
Nobuyuki Nishi2),
Hideoki Fukushima3),
Rustum Roy4),
Dinesh Agrawal4), ,1) NIFS
2) Institute of Molecular Science,3) Toyota Central R&D Laboratory, Japan,
4) Pennsylvania State University, USA

28/42

b-50

TEM

E field

H field

Starting Fe3O4
5nm
5n
5
nm

29/42

30/42

b-51

Electromagnetic Field and material Interactions
Energy released by magnetic field changes
by Motohiko Tanaka
Magnetite
Bmw // c-axis
c-axisBmw // a-axis

Hematite

B mw

Curie temperature

Magnetite (with spontaneous magnetization) is heated… through the response of spins in unfilled 3d shell,
which continues above the Curie temperature.

31/42

Results of Monte Carlo Simulation

U =   J ij si s j +  g μ B si B w
i, ji

Bw   Bw
For magnetic field reversal:
1) Energy change arises mainly from the exchange term
999Small microwave field9999Amplified by exchange
spins reorientinteractions=2) Spontaneous magnetization (second term) vanishes
above the Curie temperature, but energy change (first term)
remains finite.

32/42

b-52

An Analogy of Microwave Heating to the Classic reciprocal cycles
Condition for 2nd law of thermodynamics
Time Scale (Sec)
10 -15

10 -1410 -1310 -12

10 -1 1

Energy Supply by EM wave
(Couple to Electrons)
Speed of Light   will play a roll to collision
frequency in the analogy toclassic cycles

10 -10

10 -9

10 -8

Carnot Cycle
can not workat the frequencyof Microwave

10 -7

Classic Cycle
Archimedes Law
must be satisfied

Collision frequency>> Cycles

Collision frequency<< Cycles

New cycle theory will establish including
Quantum relaxation and classic collision

33/42

-2&0-12*232*.-"+&1&"0$)..0%*-"2*.Microwave Sintering of ZPF ceramics•

The latest results are reported for the sintering of zero-expansion Pore-free Stiffness
ceramics, called “ZPF”. http://www.ceratech.co.jp/english/product_e/01_01_05.html•

ZPF is a very unique composite ceramics. It consisted of SiC powder (about 80 mol %)and Li-Al2O3-SiO (~20%) powder.

•

It is not clear, if it is the pure liquid or pure solid sintering, as it is sintered slightly
under the melting point of Li-Al2O3-SiO powders.
Small test pieces (122 x 122 x 20 mm stacking on three layers) sintered successfully in
the isothermal insulator box by microwave.

••

Larger disks can be sintered in the large kiln at NIFS.

34/42

b-53

30m

Next Generation ELT

ZPF
1m mirror segments

35/42

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8 he densities are all most uniform except for 1250 Deg C
8Finish sintering at 12707Completely 9

36/42

2008/02/18

b-54

SEM 5000X

10micron

SEM Conventional 9bar

10micron

SEM Microwave 1bar

37/42

Larger size Disk and Large Kiln

38/42

b-55

ITER Collaboration Activities in 2007~2008
ITER

BA

By9Y. Nakamura

Check & Review•Contribution to ITER Design Review(Heating Device, SC Magnet)

Device Components•Qualifying test of SC conductors for
JT60-SA

Academic Research•Contribution to ITPA activities(~10 persons/year participate in ITPA
meetings)•Annual meeting on ITPA report anddiscussion in NIFS

Academic Research•Cooperation of building-up thecomputer simulation center(Selection of supercomputer, Physic
issues of fusion simulation etc)
Fusion Technology•Contribution to IFMIF-EVEDA(Development of TBM, R&D for
DEMO)

Fusion Technology•Workshop on ITER pellet injector(Contribution from LHD pellet injector)•Information exchange on developmentof negative-ion based NBI device

Fostering of Advanced Researchers•Communication meeting with ITER JADA member for young students in NIFS
•Support for participation to 2nd ITER International Summer School in Japan(Report meeting on ITER ISS)

39/42

Future Prospects
Fusion Reactor

DEMO

ITER & BA(JAEA)
Burning Plasma
Research

Academic Research
towards Fusion Reactor

Human Resource& Academic Res.

Academic Res.

Universities

NIFS

Inter-university
InstituteCollaboration Research

Basic Academic Researchand Education
 Establishment of ITER organization in 2007 and then beginning of device

construction phase Definite and practical contributions (human resource, review & check,qualifying test of device components etc.) will be requested.
 Academic research using reactor-grade fusion facilities (ITER & BA)•  heating physics, burning plasma control, qualifying test of blanket etc.
 Fusion technology towards building a fusion reactor (DEMO)• Material research, breeding blanket, power plant system studies etc.
 Fostering of advanced researchers for contributing to ITER & BA and DEMO

40/42

b-56

New Achievement in Fusion Science Archives (FSA)by Keisuke Matsuoka

1) Documents:
The number registered amounts to 18,000 as is shown in the ﬁgure. Main effort has been focused on
making FSA public.
2) Making Electronic Finding Aids Public:
A part of ﬁnding aids of NIFS FSA has been
made public on the basis of EAD (Encoded
Archival Description Intensive) undercollaboration with Sokendai (The Graduate
University for Advanced Studies), NIJL
(National Institute of Japanese Literature) ,KEK (High Energy Accelerator Research
Organization) and IMS (Institute for Molecularscience).
3) Lecture Meeting on Importance of Archives was held by inviting a specialist from National
Archives of Japan as a speaker.
4) Presentation of Achievements:“Special Issue on History of Fusion Research in Japan” of The Japan Society of Plasma Scienceand Nuclear Fusion Research was issued with the great contribution of NIFS FSA. Flow chart of50-year fusion research and historic documents e.g., Nobel prize-winner Yukawa’s note on fusion,
were exhibited at the annual meeting.

41/42

42/42

b-57

3-5 Highlights for long-life blanket and SC magnet materials

Current status, Research subjects
and Future plans- Highlights for long-life blanket
and SC magnet materials Fusion Engineering Research Center - (FERC)
Akio SAGARA, Director
Sagara 1 / 31

FERC in fusion research network

FERC

FERC

Sagara 2 / 31b-58

7 staffs in FERC produced world impacts
with broad collaborations in fusion research network

FERC

Fusion Research Network in Japan
LHD

Fusion Eng.Research Center

Confinement scaling Ignition access
Blanket material system& heat flux
H.Yamada,
FFHR design
d iT.Muroga,
O.Mitarai
Miyazawa(NIFS)/ Sytem Integration T.Nagasaka, M.Kondo Neutronics(Tokai Univ.)
T.Tanaka, A.Sagara/ Replacement
Helical core plasma(NIFS)(NIFS)
A.Sagara(NIFS)
K.Yamazaki(Nagoya Univ.)
Mag. material system
Structural Materials
A.Nishimura,
Magnetic structure
BlanketY.Hishinuma(NIFS)
T.Morisaki, Yanagi,
Goto, Watanabe
14MeV neutron Be Liquid(NIFS)
SC magnetshielding/ Gasmaterials.
& support
SC magnet
20°C
Blanket systemCorehigh temp.
& supprt
T.TeraiHeat flux
T-disengager
PlasmaS.Imagawa
Safety(Univ. of Tokyo)
T.Mito& CostIn-vessel
Pump
Chemistry
Component
Takahata,y
Safetys
YamadaYamada,Pump
Tritium
T.Uda(NIFS)
HX
Tamura,T storage
Purifier
Heating
Fueling(NIFS)
Divertor
Cost evaluation
ThermoTank
Turbinepumping
Virtual Reality tool
Y. Kozaki(NIFS)
fluid
N.Mizuguchi(NIFS)
T-disengager system
S.Fukada
Fueling
Power supply(Kyusyu Univ.)
Sakamoto
Thermofluid MHD Thermofluid system
H.Chikaraishi
H.Hashizume(NIFS)
S.Satake(NIFS)(TohokuUniv.)
Heat exchanger &(Tokyo Univ. Sci.)
External heating Divertor pumping
gas turbine system
Advanced first wall Advanced thermofluid
O.Kaneko, Igami S.Masuzaki,
A.Shimizu
T.Kunugi
Kobayashi(NIFS)
T.Norimatsu(NIFS)(KyusyuUniv.)(Kyoto Univ.)(Osaka Univ.)
Protection wall
Ph =0.2 MW/m 2
Pn =1.5 MW/m 2
Nd =450 dpa/30y

Self-cooled
T breeder
TBRlocal > 1.2

Radiation shield
reduction> 5 orders
Thermal shield

Vacuum vessel&
T boundarySCmagnetFFHR
Long-life > 10y
 Welding Corrosion
 Irradiation
Int CollaborationInt.
TITAN : USA (ORNL, INL,
UCLA, UCSD)
CUP : China (SWIP,
ASIPP)
Int. Network Program :EU (IPP), Russia,
Ukraine, Korea (KAERI)

Sagara 3 / 31

April 10, 2008, A.Sagara

Two sets of optimization have been studied
on LHD-type Energy Reactor FFHR towards DemoFERC

1. To expand the blanket space by adjustment of the coil pitch
parameter of the continuous helical winding, while reducing themagnetic hoop force to open wide maintenance ports,
2.
2 To
T solvel theth replacementlt difficultydiffi lt byb proposing
i a long-lifellif blanket
bl k tconcept STB (Spectral-shifter and Tritium Breeder blanket) using
carbon tiles to soften the neutron energy spectrum on the self-cooled
Flibe-RAF blanket.
Self-cooled Radiation shield Vacuum vesselFirst wall
Tiles
&
&
T breeder
mechanical
Thermal shield
T boundary
450
C
550 C
joint
coolant out
20 C
1,600 C
Plasma

C

Flibe
6Li

C
Be

Be2 C

4

LCFS
16

10

0

 Rp=16m, ap=2.35m, Vp=1744m3, B0= 4.8T,
 3GWth, 30,000 ton

1
JLF-1

1

17

SC
g
magnet

JLF-1+ B4 C(30 vol.%)40%

0.3 7.7 2

Be (60 vol.%)

Thermalinsulation
53
JLF-1

JLF-1

5 10

107 cmSTB
Replacement-free STB blanket( metal wall < 100dpa / 30y ), where
C tiles should be replaced in a few years(Redox)

Sagara 4 / 31

b-59

Present activities in FERC on liquid breeder blanket

FERC

F.E.Reserch Center
Issuescorrosion &safetyRequirements

Flibe (LiF+BeF2)

Compatibility with structurematerials is high ?
Chemical reactivity is low ?
Activation is low ?
Thermal conductivity is high ?

Self-cooling

Tritium breeding& recovery

Viscosity is low ?

Li

No by F & FT
No with N, Yes-> redox
for V
and/or coating
No
Yes
->
Yes
Yes
No
-> turbulence

MHD pressure loss is low ?

Yescollaboration
Pb-Li
No with metal
Yes for SiC
Yes
No by 210Po

Yes

Moderate

YesNo-> coating

YesNo-> coating

MHD effects to heat transfer is
low ?

?

Yes

Yes

Tritium breeding is high ?

Yes with Be-> neutronics
t
i

Yes

Yes

Yes

No
-> hot trap

Moderate

Tritium recovery is easy ?
Tritium confinement is high ?

operation

Vapor pressure is low ?
Weight density is low ?
Melting point is low ?

Data baseEnough for Fusion?

No-> coating
Moderate
Yes
No(732K)
Partly fromMSRE(US)

Yes
No
Yes
Yes(453K)
Moderatein US & JapanNo-> coating
Moderate
No
Moderate(508K)
Moderatein EU, US

Sagara 5 / 31

Specific researches in FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 6 / 31b-60

Welding for vanadium alloy became possible
FERC
 High purity large scale V-4Cr4Ti alloy ingots, NIFS-HEAT-1 and-2, were fabricated anddistributed to world research
institute.

10 cm

166-kg ingot of NIFS-HEAT-2 low
activation vanadium alloy

Laser weld

Before NIFS-HEATs, welding of
US vanadium alloy was
impossible because of low
fracture energy at impact load.

Fracture energy / J cm-2

200
V-4Cr-4Ti
RT test

NIFS-HEAT-2, Laser

150
100

Lab. 200 g scale,
Arc

Fracture-resistant Oxygen impurity reduction in
NIFS-HEATs made welding
possible for vanadium alloy.

NIFS HEAT 1 Arc
NIFS-HEAT-1,
A

Ductility limit

US, Arc

50

Weak to fracture

00

100
200
300
Oxygen impurity/ wppm

400

Fracture energy of weld joint at room temperature

Sagara 7 / 31

Vanadium alloy weld resisted 1 dpa irradiation
Fracture energgy / J mm-3

FERC

0.5 Un-irradiated
0.4

0.1
0

g
 One of causes for the degradation
is nano-size irradiation defects

Weld metal

0.3
0.2

TargetBase metal

Ductility limit0Annealing at 600oC for 1 hr
decomposed them mostly, andrecovered fracture energy.

Recovery

V-4Cr-4Ti
RT test0.1
1
10
Irradiation dose / dpa

100

Fracture energy of weld joint after irradiation
Defect – oxygen complex
Irradiation defects

Enhancementof fractureO
StableUnstable

50 nm
Electron microscope image

 Weld metal maintained highfracture energy until 1 dpa, while itdegraded at 8.5 dpa.

Decomposition

O Ti
Ti-O precipitateb-61

 The defects are stabilized by
impurity oxygen in weld metal
 It is believed that appropriate postweld heat treatment (PWHT) forms
Ti-O precipitates, and promotes
decomposition of the defects
 Investigation of PWHT effect isundergoing
Sagara 8 / 31

Bridge between standard and miniature test database
FERC

NIFS-FERC
Standard specimen Neutron-irradiated material data
has been accumulated with miniature
specimens by Japanese universities.

Correlation
Universities

NIFS-FERC
FERC accumulates standard
 NIFS
Miniature specimen Neutron irradiation test data to clarify the correlation
database
between the standard and miniature
test database
Correlation of fatigue data

Total strain rannge (%)

10 Fatigue life is estimated shorterin small strain range for hourglass
shape specimen than round-bar
shape by configuration effectStandard, Hourglass
Hirose et al.
Standard, Round bar

Short life

1

Long life

Miniature, Hourglass
Hirose et al.

JLF-1 ferritic steel

 Test with round-bar shapeminiature specimen is ongoing toreveal the specimen size effect

0.1
102

In air.
RT

103
104
105
Number of cycles to failure
Sagara 9 / 31

Corrosion characteristics of JLF-1 steel in molten
salt Flibe and liquid Li was investigatedChemicalCorrosion

Chemical corrosion& Slight erosion

Erosion/Corrosion
ErosionSaturation

Non -saturation

Corroded layer

Corroded layer

Corroded layer

RAFM steel

RAFM steel
Thermalconvection

RAFM steel

StaticCapsuleSpecimen

Flowing test

FERC

Corrosion
characteristics of
JLF-1 steel in Flibe,
Flinak and Li were
investigated bymeans of static test
and thermal
convection tests.

試験片

内筒
Do

DH

D
m

b

Test pot

Propeller

l

D
D/3

∆T Small∆T Large

Equilibrium

Real condition

Present work

Future workb-62

We are trying to
d forceddofdconvection test
based on our skill
and technique forthe corrosion test at
high purity
conditions.
Sagara 10 / 31

Low corrosion rate of JLF-1 steel in high purity
Flibe at static condition was confirmed

FERC

Flibe

Purification of Flibe
was succeeded.

DifficultCorrosion tests in high purity Flibe
were performed. Corrosion rate andmechanism in static condition wasmade clear.
It was found that
corrosion in Flibe was
influenced not only by
F but also O and N.

100μm/year

100

Possible
10μm/year

600oC

10

600oC

600oC

600oC

Good

o

600 C

500oC

500oC 600oC

500oC

1

First Flinak was produced
produced. Chemical
characteristics of Flinak was similar to
Flibe. Flinak will be used as simulant ofFlibe for future corrosion study.

First Flinak

1000 hours
HF: 180 wppm
High purity Flibe

1000

Corrosioon loss( µm/yyear )

High purity of Flibe was successfully
produced by NIFS - Tokyo univ.
collaboration.

Flinak

JLF-1

316L

304 stainles steel

Hastelloy Inconel Inconel
600
625
C-276
Award for young
Ni based alloy
scientist (AESJ)<Reasonable>

The corrosion inhigh purity Flibe waslow.
Sagara 11 / 31

Phenomenon of “Corrosion and Phase change” of JLF-1
in liquid Li was newly found by high purity corrosion test
FERC

Chemical corrosion and phase change of RAFM
After
in LiBefore

exposure (JLF-1)

Li exposure (JLF-1)

Softening
S ft iMartensite

Li convection loop at
high purity condition
was successfully
operated.

Ferrite
5μm

Fe
C
a

c
C depletionaaMartensite (bct)aaFerrite (bcc)

Corrosion wascaused by theformation of LithiumChromium-Nitrogen
Chromium
Nitrogencompounds.
The phase change
was caused by C
depletion.

Li loop at high purity condition was successfully operated !!

b-63

Sagara 12 / 31

Design and feasibility studies for forced convection loopof molten salt Flibe and liquid Li were advanced
Ultrasonic flow meter(Future work)
DesignThermal convection loop

study forFlibe loop

FERC

Development of mechanical lift
pump (T>500˚C)

Corrosion of candidatesteel (316L type)
Corrosion of candidate
for Li loop tube
steel(316L type) for Flibeloop tube

Piston Piston

Tank
Tank

Bellow valve
development

Selective corrosion
at grain boundary

Laser induced break
down system

Mechanical pump for
Selective
dissolution of Cr high temp. fluid

Design study for Li loop

Hydrogen sensor
for melt
Electromotive
force (EMF)

Compact type Li loop with flow meter

Sagara 13 / 31

Er2O3 MHD coating exhibited good compatibility with Li,
especially for high crystalline coating

FERC

Er2O3

Y2O3 CaZrO3

 For reduction of MHD ppressure drop
p in Licooled blanket system, electrical insulating
coating is required inside of coolant ducts.

 Er2O3 and Y2O3 were selected
as candidates for MHD coating
for their chemical stabilities.

Reduction of MHD pressure drop
Mass loss of the bulk ceramics byby ceramic insulator coating
exposure to Li Er2O3 coating was fabricatedby PVD process

ExfoliatedSubstrate Temp.
RT High crystalline coatingexhibited good compatibility
with Li

850K

773K

873K

973K

1000hr in liquid Li
Compatibility of PVD coating with Li(Er2O3 coating on V-alloy, ~1 m in thickness,
Collaboration with ORNL)

b-64

Sagara 14 / 31

Advanced coating technologies and function oftritium permeation barrier have been demonstrated
FERC
Er2O3
Liq. Li+ Er(0.15 wt%)
600 oC

Er3+

V-4Cr-4Ti

O2-

5 m

Development of in-situ
coating method for Li blanket

Er

Coating fabricationby MOCVD method

JLF-1
JLF
1
0.25μm
1μm

3 orders

V-alloy
Double layer coating
by EB-PVD(Collaboration with LLNL) Advanced coating by insitu and MOCVD (metalorganic chemical vapor
deposition) process havebeen developed for large
area coating Double layer coating has
been also demonstrated
for unti-corrosion coating Er2O3 coating exhibited
3-order reduction in H
permeability

H permeability of coated JLF-1
Collaboration with U. Tokyo

Sagara 15 / 31

Specific researches in FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 16 / 31b-65

Quick feedback in neutronics design and modification have been conducted
and Tritium breeding (TBR>1.1) and sufficient shielding can be achieved
FERC

3-D neutronics calculations
by MCNP Monte-Carlo code
Blanket design

Quickfeedback Blanket structures andconfigurations have been
investigated by simulations ofneutronttransport,tt tritium
t iti
production, damage, nuclear
heating, radioactivation etc.
 New 3-D neutronics calculation
system for helical powerreactors has been developed.
self sufficiency
 Tritium fuel self-sufficiency
could be achieved in helical
reactor (Global TBR: >1.1)

3-D analysis
Design modification

 Semi-closed divertor system
has been proposed to avoid
neutron streaming
Sagara 17 / 31

Neutronics designs are being validated by DT neutron irradiations
FERC

D+ beam~50 cm

T targetDT neutron irradiations
on blanket material assemblies
are being performed
at FNS facility (JAEA)

Li/V-alloy
assembly

at FNS
facility(JAEA)

 For accuracy evaluations of5
4

ExperimentCalculation

Li

Li

3
2
1
0
-5

0

5

10

15

20

25

Position (cm)30

35modeling method, calculation code andnuclear data.
 Validation of neutronics performanceand information on design margins
for TBM and DEMO reactor designs
can be obtained.

Accuracy of radioactivity calculation
for liquid blanket materialsof V-alloy, Er and F was <~20 %~10%

V-alloy-29 6(x10 / Li atom/sourrce neutron)

Tritium prodcuution rate

Evaluation of tritium production rates
in Li/V-alloy assembly with small neutron detectors

40

Accuracy of tritium production ratefrom Li-6 in Li/V-alloy assembly
was <~10 %Comparison between calculated andmeasured tritium production rates in Li/V-alloy assemblyb-66(Tentative analysis)

Sagara 18 / 31

Specific researches in FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 19 / 31

Collaborative Study on Neutron Effect on
Superconducting Magnet Materials

FERC

14 MeV neutron irradiation
TC measurement

Arrangement

JAEA FNS

HOT LAB.
Oarai center
IMR, Tohoku
Univ.

14 MeV neutron source
GM refrigeration

Fission reactor
irradiation
JRR-3 (JAEA)
BR2 (Belgium)

Sample transfer
IC, BC2（<100 kBq/sample)
measurement
HFLSM
IMR, Tohoku
Univ.
28T hybrid magnet

15.5T magnet will be
installed in hot lab.
S
Samplesl(2010)
Industries,
NIFS,
Institutions
JAEA,(Strands,
NIMS,
insulators)
Universities
Sagara 20 / 31b-67

Critical Current of NbTi, Nb3Sn, Nb3Al
after 14 MeV Neutron Irradiation> BC2 of Nb3Sn does notchange after neutron
irradiation. (~25.5 T)
The World-first Data.
Pinning force might bestrengthened and/or
number of pinning sites
be increased by Knockon Effect of neutron.

Criticall Current (A)> IC of Nb3Sn increased.
Dependence of change in IC on
magnetic field was clarified.
200
The World-first
World first Data.
Data> NbTi and Nb3Al do not show
IC increase.
150

Nb3Sn NonNb3Sn NonNb3Sn Irrad.
Nb3Sn Irrad.
Nb3Al NonN
Nb3Al Non-

Improvedp

FERC
Nb3Al Irrad.
Nb3Al Irrad.
NbTi NonNbTi NonNbTi IIrrad.
d

Nb3Sn

Nb3Sn
0.7mm

NbTi
NbTi

100

Nb3Al
0.7mm
Nb3Al

0.82mm

50

BC2(Nb3Sn)14 MeV neutron
21

2

1.78 x 10 n/m

0

8

12

16
20
Magnetic field (T)24
Sagara 21 / 31

Je of V3Ga wire was enhanced by new PIT process(R&D of Low activation superconducting wires) Bc2 was increased by the
new PIT (powder in tube)
process using “high Ga cont.
compound”.
p
(21T
(
23T))

FERC

RHQ-Nb3Al(1.04mmφ) Engineering Jc of PIT
processed V3Ga wire showed
100 A/mm2 around 18 T.

Bi-2212(0.8mmφ)
RRP-Nb3Sn(0.9mmφ) The optimum cross-section
configuration was required toiimprove
Jc-B
B property.
t

PIT-V3Ga(1.04mmφ)

 The strain effect (highstrength) and multifilament
deformation will be
investigated.

Bronzed-V3Ga(0.4mmφ)High Tin
Bronzed-Nb3Sn(0.8mmφ)

Sagara 22 / 31b-68

Selected Publications in FY2006 to FY2008
FERC
Total Number of Papers

TitlesReactorDesignStudies

BlanketMaterials

Neutronics

Superconducting
MagnetAuthors

Journals

Optimization activities ondesign studies of LHD-type
reactor FFHR

A. Sagara, T.Tanaka,
T. Muroga et al.

Fusion Engineeringand Design(accepted)

Fluoridation and oxidation
characteristics of JLF-1 and
NIFS-HEAT-2 lowactivation structural materials

T. Nagasaka, M.
Kondo, T. Muroga,
N. Noda, A. Sagara
et al.

Journal of Nuclear
Materials (accepted)

Metallurgical study on
corrosion of austenitic steels
in molten salt LiF-BeF2(Flibe)M. Kondo, T.
Nagasaka,
A. Sagara, N. Noda,
T. Muroga, et.al

Journal of Nuclear
Materials (accepted)

First
AuthorStudents

3

Collaboration
Domestic

Within
NIFS

Int'l

15

6

3

8

3

5

1

6

5

13

8

4

3

Microstructure of Creepdeformed V-4Cr-4Ti
Strengthened by Precipitation
and Cold Rolling

T. Muroga, T.
Nagasaka, J.M.
Chen, Y.F. Li and H.
Watanabe

Journal of Nuclear
Materials (accepted)

Neutronics investigation ofadvanced self-cooled liquidblanket systems in the helical
reactorT. Tanaka,
T
Tanaka A.
A
Sagara, T. Muroga
and M.Z. Youssef

Nuclear Fusion
Fusion,Vol
Vol
48,035005 (7pp)(2008)

Change in Properties ofSuperconducting Magnet
Materials by Fusion Neutron
Irradiation

A. Nishimura, S.
Nishijima, T.
Takeuchi, T.
Nishitani

Fusion Engineeringand Design, Vol. 82,
pp. 1555-1560(2007)The new route process of
V3Ga mono-cored andmultifilamentary wires using
high Ga content Cu-Ga
compound and V matrix
precursor

Y. Hishinuma

Journal of Physics:
Conference Series
vol.97 no.
pp.012131 (2008)

16

Total

37

7
11

40

2
8 23 /12
Sagara31

Future plan of FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 24 / 31b-69

System integration for fuel and heat recovery in blanket
FERC

Online hydrogen sensor
Hydrogen charge

H dHydrogenpermeableblarea
Mass analyzer
Hydrogen recovery
H2

H2

Flinak
T1

T2

H2

T3

Heat

H2

H2

H2

sampleHeaterGas
Heat recovery
analyzer
Flowing technology
Hydrogen permeation barrier
Heat

Heater

System integration for
the feasibility studies
on compatibility ofhydrogen recovery
and heat exchange inthe flowing system isplaned with the use ofp
Flinak towards the
Demo reactor.

Sagara 25 / 31

Future plan of FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 26 / 31b-70

Future plan for neutronics

FERC Each of JA, US, EU and CN groups is making efforts
for importing 3-D CAD data into neutronics
simulations. But in most cases, using simple surfaces(like plane, sphere, torus, quadratic surfaces etc.) forsymmetric geometries
geometries.

 Collaborative studies for importing
CAD data of asymmetric geometries
have been started with ASIPP, China.
 Treatment of complicated spline
surfaces are challenging.

CAD geometry imported
Into conversion system MCAM,
developed by ASIPP, CHINA

 Neutronics evaluation and validationb DT neutron irradiations
i di i((at FNS,FNS
by
JAEA) will be performed on armor,shielding, reflector materials etc.
 Aiming for mockup test of liquid
cooled TBMs in the future
Neutronics experimentson blanket material assembly

Sagara 27 / 31

Future plan of FERC
1. Blanket material system
2. Neutronics
3 Magnet material system
3.

Sagara 28 / 31

b-71

Future Plan of Superconducting Magnet
Technology Research for Fusion
FERC Collaborative network for neutron
irradiation research will be expanded todifferent research fields.
> NextN t ttarget:t In-situ
I it observationbtiduring/after neutron irradiation at ~10 K Neutron irradiation effect on superconducting wires, tapes and insulators.
> Higher radioactive samples will beable to be evaluated at hot lab.
> All Nb3Sn strands (11 types) for ITER
TF magnet will be tested.

Neutron Irradiation system
at ~10 K will be installed in
JMTR at Oarai.
Conceptual design activity
started. (Head; JAEA)
15.5 T superconducting
magnet and 500 A current
lead will be installed at hot
lab in Oarai center of
Tohoku Univ.
1.17 M$ was approved by
MEXT for 2008, 2009 and2010. (Head; Tohoku Univ. ) Development of superconducting
conductors and magnet structures forlarge electro-magnetic force.
Candidate: Nb3Al, YBCO, Bi2212, etc. High strength material.
Sagara 29 / 31

Roadmap for FERC to Demo reactor

FERC

FERC
FERC
 with applying
external resources as the COE ofcollaborations
 with contributing
ITER, BA and IFMIF
 and educating Dr.
course students.
Sagara 30 / 31b-72

Summary

FERC

1. FERC produced world impacts with broad collaborations in fusion
research network
On long-lifegliquidq
Flibe and Li blanket based on the reactor design,g ,2. O
large R&D progress was made on low activation V-alloy and ferritic steel
for miniature test, welding, irradiation, corrosion and coating.
3. On neutronics for reactor design, new R&D’s have been initiated for aquick-feed back 3D code system and 14MeV irradiation mockup tests.
4. On SC material system, wide R&D progress has been made withcollaboration networks on neutron irradiation effects and low activation
SC materials.
5. Future plans are addressed for R&D on system integration of liquid
breeder blanket, neutronics and SC magnet technology as the COE ofcollaborations with applying external resources.

Sagara 31 / 31

b-73

3-6 High-Beta and Related 3D MHD Characteristics

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

High-BetagandRelated 3D MHD Characteristics

Satoru Sakakibara
National Institute for Fusion Science

1/32

OutlineMotivation
Subjects of high-beta stellarator/heliotronsgpResults of recent high-beta
experiments- High beta operation- Related physics:- MHD equilibrium- MHD stability- Confinement and transportpDiscussion for realization of reactor
Summary and the next subject

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-74

2/32

Motivation
Production of high- plasma is the common subject in magnetic
confinement systems
Production of High- Plasmas
Transport

MHD Equilibrium

MHD Stability

NC, turbulence etc.

stochastisity etc.

growth of MHD mode etc.

Experimental Verification

Optimization of Configuration

Economical Reactor

Understanding of high- physics related to -limit
Tokamak: NTM, RWM, ELM... Helical: Stability? Equilibrium? Transport?
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

3/30

Subjects of High-beta Heliotrons
MHD equilibrium, stability and transport are key issues for production ofhigh-beta plasmas:
MHD Equilibrium:
Change of magnetic topology and relationship with beta
beta-limit
limit- Stochastization of peripheral magnetic field lines
MHD Stability:
Effect of pressure-driven mode (Interchange and Ballooning modes)- Magnetic hill in the periphery< > ~ 0 %Transport:
transport related with finite- effects(magnetic topology, beta and so on)< > ~ 4 %- Particle loss due to an increment of helicalripple, turbulence caused by steep p

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-75

4/32

High- Experiments in LHD
Achieved  has increased year by year, with an increment of heating power andadjustments of magnetic configurations.
Bt ((T))

0.5

0.45

Ap

5.8

6.3

0.425 0.41
6.6

R = 3.9 m, aeff ~ 0.65 m, Bt < 3 T
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

5/32

Rax is a key parameter for high-Magnetic axis position is one of configuration
parameters characterizing MHD and transport:
InwardoutwardRax

Stability:
hill

well

Equilibrium:
weak dependence

Transport:
Increment of helical ripple

Heating:
Prompt loss of NB

Confinement:(Experiment)

shift
3.6 m
Shafranov shift

Shafranov shift deteriorates transport and heating
efficiency, although it is better for stability
 adjustment of aspect ratio
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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6/30

Plasma Aspect-Ratio
Plasma aspect-ratio can be changed by controlling current center of HC
Increment of Ap leads to a reduction of Shafranov shift
Poloidal Coils

 favorable for heating efficiency, transport and eq. -limit
 enhanced magnetic hill and reduction of magnetic shear optimum Ap for high-beta plasma production

HC-O
HC-M
H-M
HC-I

PlasmaHelical Coil

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

7/30

Experiments for Ap Optimization
Optimum Ap was found out in the experiments.
Sakakibara S et al 2006 FS&T 50 177

Enhanced Edge MHD(m/n = 2/3)
Ap = 6.3

Increment ofheating efficiency

Ap = 6.6
Minor collapse
caused by m/n =1/1 mode

Ap = 7.1

Ap = 7.7

small Rax shift, reduction of eff

Ap = 8.3

strong shear，weak magnetic hill
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-77

8/30

High-beta Discharge – Pellet Injection –Perpendicular-NBI was applied after
several pellets were injected andtangential NBI is turned off whichleads to reduction of Shafranov shift.

Rax = 3.6 m, Bt = -0.425 T
P-NBI

MHD activity is not enhanced in highbeta regime with more than 4 %0.5
ne (1019 m-3)
0.4

4

0.3
0.2
02
0.1
0
0

2
Te (keV)

0.2

0.4

0

0.6

aeff (m)13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

9/32

High-beta Steady State Discharge<dia>max ~ 4.8 %, 0 ~ 9.6 %, HISS95 ~ 1.1

Rax = 3.6 m, Bt = -0.425 T

Plasma was maintained for 85E
Shafranov shift /aeff ~ 0.25
Peripheral MHD modes are dominantly
observed.

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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10/32

Results of High- Experiments
5.1% plasma was maintained formore than 10E, whereas 4.8 % one
was for 85 E

Beta increases with input power
No disruptive phenomenon

The duration time in gas-puff
discharge is limited by NBI

Sakakibara S et al 2008 Plasma Phys. Control. Fusion 50 12 124014
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

High- physics
relatedl t d tto -limit
li it
MHD Equilibrium
MHD Stability
C fConfinement
and Transport

b-79

11/32

How about MHD Equilibrium?
HINT2 Equilibria

The connection length in the
periphery becomes to be shortwith the increment of the beta
The volume inside LCFS is
drastically changed at 4.8 %, andthe stochasticity erodes from theouter region
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

13/32

Equilibrium in <>=4.8% Plasma
Te gradient in the stochastic area is still
maintained at 4.8 % plasmaInflection points at profile start toappear,appear corresponding to the LCFS
The volume inside LCFS isdecreased by 32 % compared to thevacuum case- No degradation of achieved inthe present  range- It is predicted that the stochastic
region is extended further inhigher- range

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-80

14/32

Prediction of Equilibrium Beta-Limit
Stochastic magnetic field structure penetrates to core?

Suzuki Y et al 2008 IAEA FEC2008
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

15/32

Spontaneous change of Magnetic Islands
Healing and growth of the magnetic island have been observed in theexperiments and are related to collisionality and beta.
High-beta (4.8 %)External Perturbation
given by external coils(m/n = 1/1)

R (m)w11/ap > 0.17

 Healing

100

h*

w11/ap ~ 0.17
1.5 Te (keV)
1.0
0.5
0
1.5 T (keV)
e
1.0
0.5
0
3
4

- vh* ~ 5,
5  ~ 1.818%GrowthR ~ 12 ms(Te = 0.1 keV, L = 0.1 m)

10-1

island scan in high-

Healingg
w11/ap ~ 0

10-2
0

0.2

0.4

0.6

0.8

(%)
Narushima Y et al 2008 NF 48 7 075010
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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16/30

Discussion on MHD equilibirum
Can pressure and the gradient remain in the stochastic area?
 common to ELM-RMP etc.
High-betagplasmap- Perpendicular transport is dominant in high vh* plasma- Effects of peripheral MHD activities- Healing of magnetic island
 not included in HINT2 Equilibria! (Bootstrap effect etc.)
Avoidance of Equilibrium
Beta-limitq- Real-time Control of Magnetic axis (2008-)

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

High- physics
relatedl t d tto -limit
li it
MHD Equilibrium
MHD Stability
C fConfinement
and Transport

b-82

17/30

How about MHD Stability?
Linear theory
Mercier criteria are extended to theperiphery
Resistive mode is unstable in themagnetic hill

Experiments<dia> reached 5.1 %Mercier criteria do not limit theoperation regime
Ideal low-n mode with less than acertain growth rate is harmless
Internal and external measurements
indicate that dominant low-ordermodes are excited at n/m  1 in high regime.
 characteristics of observed mode
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

19/32

S Dependence of MHD Mode
Clear S dependence of mode amplitude,
wMHD  S-0.355, has been foundThis tendency can be found in thecomparison with CHS (low-S).
(low S).
CHS: S=103 ~105

|Bt |  1.5 T

LHD: S=106 ~108

aBT 3 / 2
S  R  1/ 2 e
 A ZAne< dia> (%)

DI < 0

Sakakibara S et al 2001 NF and 2006 FS&T
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-83

20/32

Linear Stability Analysis – Resistive mode –Resistive Interchange Mode (FAR3D)
The growth rate and the mode width is
proportional to S-1/3 in ideally-stable plasma
S dependence become to be weak when
DI > 0Experiments:- wMHD  S-0.355 at DI < 0- DI ~ 0.1 at <dia> = 4.8 %consistent with experimental results!
- The observed low-n MHD modes are
expected to be suppressed in the reactor withhigh-S- However, ideal mode should be stabilized inorder to keep this S dependence.
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

21/32

Linear Stability Analysis – Ideal mode –Mercier Modeunstable in the magnetic hill
DI-max ~ 0.25, DI ~ 0.1 (/2 = 1)
Ideal Low-n Interchange Mode
(TERPSICHORE[1])• stable (no mode with /A > 10-2 )• Threshold /A ~ 10-2 was obtained
through comparison between
operational region and calculation
Watanabe K.Y 2005 Nucl. Fusion 45 11 1247

High-n Ballooning Mode [2]localized in the periphery with magnetic
hill and local magnetic shear[1] Cooper W A 1992 Plasma Phys. Control. Fusion 34 1011
[2] Nakajima N et al 2007 Fusion Sci. Technol. 51 79
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-84

22/32

MHD Database in Stellarator/Heliotrons
Plans for MHD database in stellarator/heliotrons
Common understanding of characteristics of MHD activity and its
effects on profiles and confinement- Empirical scaling of onset parameters- Parameter dependence of saturation level of the fluctuation- Validity of linear stability boundary (DI, DR, Low-n alnalysis) contribute an extension of free degree of magnetic configurations forreactor design.
Obj t : thtd fluctuation
fl t ti levelll (amplitude)(
lit d )
Objects
the onsett parametersandDevices: LHD, CHS, Heliotron-J, W7-AS, TJ-II, H-1 etc.
Kick off : January 2009 ~13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

23/32

Onset and Fluctuation Level of MHD modes
Passive Experiments
Parameter Dependence(S, , d/dr, Ip etc.)
Configuration Dependence(Well/Hill, magnetic shear etc.)
Active Experiments

1T

p control by movable limiter
Gas-puff Modulation
Vertical Field Control by PC (2008-)
 finding the stability boundary
Sakakibara S et al 2006 Plasma and Fusion Research 1 003
Sakakibara S et al 2006 Plasma and Fusion Research 1 049
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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High- physics
relatedl t d tto -limit
li it
MHD Equilibrium
MHD Stability
C fConfinement
and Transport

How about confinement and transport?
Global energy confinement gradually degrades with increasing 
Reduction of HISS95 is caused by an increment of local transport in the periphery

GRB=*B, *=s/ap
Watanabe K.Y 2005 Nucl. Fusion 45 11 1247
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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26/32

Local Transport and Density Fluctuation
It is possible to interpret the local transport
by using resistive-g mode model

geometry

Density fluc. increases with plasmaCarreras B A et al 1989 Phys.Fluids B1, 1011

102

 /
eff

GMTe

(= 0.9)23

FIR interferometer(wavelength ~
30mm)

101
100
10-1
0

1

4

<dia> (%)
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

27/32

Discussion for Realization of Reactor
From experimental knowledge of LHD...
MHD Equilibrium
Plasma confinement and achieved  were limited by the stochastization of magnetic fieldstructure in W7-AS (M.C. Zarnstorff, IAEA2002). Erosion of stochastisity from the edge
appears in highhigh  LHD according to HINT calculation.
calculation
 Securing the magnetic surfaces is one of key issues for higher-.
MHD Stability
Mercier criteria are not always important for the operation. However, we should know thevalidity of linear theory on Mercier and ideal low-n modes for reactor-design.
Resistive mode is expected to be suppressed even in the magnetic hill, in reactorplasma with high-S if ideal mode is stable.
C fi
Confinementt anddT
Transportt
HISS95 of more than 1 is kept in the  range with  5 %, whereas reduction of global
energy confinement is caused by increasing local transport in the periphery
If it is caused by the resistive-g mode turbulence, the turbulence is expected to be
suppressed by increasing S as well as low-n mode.
High-n ballooning effect should be clarified.
13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-87

28/32

Summary
Volume averaged beta value of 5.1 % was successfully obtained in recent
experiments and steady-state plasma with 4.8 % was maintained for 85E.
Shafranov shift is smaller than conventional beta-limit. Although it is predictedthat an extension of stochastic region due to finite
finite-beta
beta effects, the pressure
gradient seems to be still maintained in that area.
Although low-n MHD activities affect local profiles, they do not limit theachieved beta. The saturation of the mode has clear S dependence, which isqualitatively consistent with the model of the resistive interchange mode.
Global energy confinement gradually degrades with beta, which is caused by
the increment of local transport in the periphery. The effects of the spontaneouschange of the equilibrium, high-n ballooning mode and the turbulence on it
should be clarified.

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

29/32

Next Subjects related with High-Production of high- plasma with more than 5.1 %- Restriction of Shafranov shift are required for maintaining high heating
efficiency of NBI and avoiding equilibrium beta limit.
- Real-time
Real time control of Rax by external coils starts in FY2008- It is expected to contribute researches related to finite- effects
Search for low-, low- andhigh-S regime with high-
- Investigation of physics related tohigh- in the low-*, low-* andhigh-S regime is required
required.

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

b-88

30/32

First Trial of Rax-scan experiments
Rapid sweep of Rax induced minor collapse• Reference:
Rax = 3.6 m, Bt = -0.425 T, Ap = 6.6<> ~ 4%
• Rax =3.6 m  3.5 m for 1.4 sec (Preset)• Collapse : ~ 1.05 sec in core

Flattening

13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

31/32

Scenario of High- operation using Rax control
How to sweep Rax is a key for an access to higher- regime
enter the plasma to “second stable” regime  stable and good heating!
clarify “actual” unstable regime experimentally  understanding of physics!
vanish of m/n = 2/1
resonance due to Ip

High heating efficiency<> (%)

Plan for high-Core

Rax=3.6 m

unstable

3.6 m3.5 m
Rax=3.5 m
3.5

Sakakibara S et al 2006 Plasma and Fusion Research 1 003

3.6

3.7

3.8

Rax (m)13 Dec., 2008, Special Review Meeting, Takayama, S. Sakakibara

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32/32

3-7 High Density Operation and Its Prospect for Helical Reactor

December 13, 2008
HIDA Earth Wisdom Center, Takayama
NIFS Special Review Meeting by Advisors and Foreign Researchers in FY 2008

High Density Operation and Its
Prospect for Helical Reactor
Ryuichi Sakamoto
National Institute for Fusion Science

Contents
High density / high performance discharges in LHD–Internal Diﬀusion Barrier (IDB) formation in LHD–Sustainability of pellet fueled high performance plasma
Feasibility of IDB scenario for helical reactor–Power balance calculation with plasma profile effects
Prospect of pellet refueling for fusion reactor–Prospect

1

R. Sakamoto
National Institute for Fusion Scienceb-90

Particle control in fusion reactor
Core fueling plays a primary role in a future fusion reactors in whichmagnetically confined burning plasma is sustained by its own  particle
heating.
–High priority issue
Pellet injection is one of the best solution for core fueling at this time.
–Direct particle supply capability to the inside of LCFS
–Negligibly low energy requirement for core fuelingExperimental study aiming at high performance plasma that is compatible
with core fueling has been performed in LHD.

R. Sakamoto

National Institute for Fusion Science2

Large Helical Device (LHD) and pellet injectors
Neutral beam heating (NBI)Three negative ion based high energy(up to 200 keV) tangential NBIs
A perpendicular NBI (40 keV)PelletP
ll t injectors
i j t–10 barrels in-situ pipegun injector, since 1998
–Repetitive pellet injector,
since 2002

R. Sakamoto

National Institute for Fusion Science

b-91

3

10 barrels in-situ pipe-gun injectorNumber of Barrels: independent 10 barrels
Pellet Size: 3.4 mm3.4 mmL, (optional: 1.0 mm – 4.8 mm)Pellet velocity: 1200 m/s, (optional: 100 m/s – 1200 m/s)
Materials: Hydrogen,Hydrogen (optional: Neon,
Neon Neon doped hydrogen)Pumping of Propellant gas : 3 stage differential pumping system
The world’s first liquid-He free pellet injector with a pair of cryo-coolers

R. Sakamoto

National Institute for Fusion Science4

Repetitive pellet injector with screw extruder
Pellet Size: 3.0 mm3.0 mm
Injection Frequency: up to 11 Hz
Steady state operation–Liquefaction and solidification is simultaneously
processed with solid hydrogen extrusion–Continuous production of solid hydrogen rod–55 mm/s extrusion for 3.0 mm rod–liquid-He free with a pair of cryo-coolers–Contribution to ITER pellet injector development

R. Sakamoto

National Institute for Fusion Science

b-92

5

Contents
High density / high performance discharges in LHD–Internal Diﬀusion Barrier Formation in LHD–Sustainability of pellet fueled high performance plasma
Feasibility of IDB scenario in fusion reactor–Power balance calculation with plasma profile effects–Prospect
Prospect of fueling for fusion reactor

6

R. Sakamoto
National Institute for Fusion Science

Whatʼs Internal Diffusion Barrier?
High-density improvement mode in LHD–Characterized by steep density
gradient
plasma to access a–Enables core phigh-density/high-pressure regime–Reproducibly obtained by employing
intensive multi-pellet injection

particle transportp p
propertyp yCharacterize p
Explore operational limit of the IDB
plasmasR. Sakamoto

National Institute for Fusion Science

b-93

7

How to make the IDB<

Intensive multi-pellet injectionIDB formation in Density decay
phase
Temperature recovery rate
Core density decay rate

R. Sakamoto

National Institute for Fusion Science

8

Particle transport property of IDB plasmas
Particle transport coefficient of IDB plasma is estimated from
relationship between time evolution and gradient of density profiles.

Core plasma Diffusivity is kept at low level evenhigh density gradient (D≈0.05 m2/s).
 Convection velocity increase in latter
half of IDB period (V≈0(V≈0. 25 m/s).
m/s)

Mantle plasma Larger diffusivity than core plasma
during IDB phase (D≈0.43 m2/s)

R. Sakamoto

National Institute for Fusion Science

b-94

9

High density achievement with pellet fueling

25TThe maximum attained central density is >11021 m-33 at Bt = 2.5
Low density mantle plasma prevent radiation collapse
Attainable density is restricted by power balance.
–Lack of central heating power due to high density put a ceiling on
attainable density
Pellet cannot ablate effectively at low temperature plasma (<300 eV)
R. Sakamoto

National Institute for Fusion Science

10

Quasi stationary sustainment of pellet refueled
plasmaConstant central density and temperature are sustained quasi-stationary
by using repetitive pellet injection. (<1.2×1020 /m3)
Larger mass are required in order to sustain high density IDB plasma.
(> 5.0×1020 /m3)

R. Sakamoto

National Institute for Fusion Science

b-95

11

New facilities for high density sustainment
experiments
20 barrels in-situ pipe-gun pellet injector (under development)Closed helical divertor (under design)–Active pumping capacity
corresponding to throughput ofmassive pellet fueling–Steady state heat removal
capability
R. Sakamoto

National Institute for Fusion Science

12

Operational Limit of IDB Plasmas
Lack of central power deposition–High density plasma inhibit NB
penetration to the core
put a ceiling on attainable densitydue
d tto ineffective
i ff ti pellet
ll t ablation
bl ti
slackened growth state of thepressure rise in high density
regime–Efficient central heating is key toextend operational regime

CDC

Core dCdensity
it collapsell(CDC) eventt–Core density is abruptly expelled athigh pressure regime.

R. Sakamoto

National Institute for Fusion Science

b-96

13

IDB (High-central β) Discharge with CDC
CDC is an abrupt event where the coredensity is collapsed within 1 ms.
–much faster than other MHD relaxation
events in LHD
Mechanism of the CDC has not beenclarified.
Potential solution: Suppression of
Shafranov shift–Vertical field control (inward shift)–P-S currents suppressionAspect ratio (reduce minor radius)
Ellipticity (vertical elongation)

R. Sakamoto

National Institute for Fusion Science

14

Suppression of Shafranov Shift by Vertical
Elongation
Vertical elongation is effective to suppress the Shafranov shift–CDC limits central pressure for κ< 1.2–CDC disappears when κ> 1.2–Higher central beta has been achieved under CDC free condition

R. Sakamoto

National Institute for Fusion Science

b-97

15

Operation Regime of high-beta plasmas

MHD activity and CDC
event should be avoided inorder to form a high-centralbeta plasmas– Inward Rax: core-localized MHD– Outward Rax: CDC

The control of the magnetic
axis is the key

National Institute for Fusion Science

R. Sakamoto

16

Contents
High density / high performance discharges in LHD–Internal Diffusion Barrier formation in LHD–Sustainability of pellet fueled high performance plasma
Feasibility of IDB scenario in fusion reactor–Power balance calculation with plasma profile effects
Prospect of fueling for fusion reactor–Prospect

17

R. Sakamoto
National Institute for Fusion Scienceb-98

Model Calculation with Plasma Profile EffectGeneral parameters–Major / Minor radius: 15 m / 2.3 m–Magnetic field: 8 T–Zeff: 1.5–Improvement factor: 1.2
Model Profiles–IDB
IDB Profile (Core fueling):
 ∆m=0.4, ∆b=0.3, nm=1×1020 m-3–Parabolic profile (Peripheral fueling):
 n=n(0), T=T(0)(1-ρ2)

R. Sakamoto

National Institute for Fusion Science

18Power Balance and Ignition Condition
Alpha heating:Bremsstrahlung loss:
Confinement
loss:
C f

(for Parabolic profile)(IDB condition)= 0.030 03

Db< 0.15 m2s-1
m< 5 m2s-11(for IDB profile)Ignition Condition:
R. Sakamoto

National Institute for Fusion Science

b-99

19

Operational Regime
Ignition regime: Pα - Pb - PL ≥ 0
IDB profile allow access to ignition condition with lower temperature.
–Bremsstrahlung loss is suppressed–T(0)=
T(0) 7 ~ 10 keV,
keV n(0)=n(0) 5 ~ 7×1020 m-33

IDB Profile

Parabolic Profile

National Institute for Fusion Science

R. Sakamoto

20

Contents
High density / high performance discharges in LHD–Internal Diffusion Barrier formation in LHD–Sustainability of pellet fueled high performance plasma
Feasibility of IDB scenario in fusion reactor–Power balance calculation with plasma profile effects
Prospect of fueling for fusion reactor–Prospect

21

R. Sakamoto
National Institute for Fusion Scienceb-100

Validity of NGS pellet Ablation ModelNeutral Gas Shielding (NGS) Models–Ablated materials (pellet ablatant) shield
the pellet from a background plasma–Electron heat flux dominate the pellet
ablationenergy flux to the ablatantcross section in the ablatant– particles have less impact on the pellet
ablation.
The NGS models can explain the pellet
penetrationt ti ini LHD.
LHD

R. Sakamoto

National Institute for Fusion Science

22

Pellet refueling to fusion plasma
Pellet penetration to large scale IDB plasma is estimated by using NGS
pellet ablation code.
–Major / Minor radius: 15 m / 2.3 m–Te(0)= 7.0 keV, ne(0)≈ 6×1020 /m3, IDB profile–Fueling
F li ratet Npellet/Nplasma≈ 0.2
0 2 (same(
ffueling
li ratet as LHD experiment)it)Pellet penetrate to ρ≈ 0.5 underfeasible pellet velocity.
–Relatively low temperature
operation allow the pellet
penetration–High
Hi h ddensityit operation
ti allowll
the large pellet injection and it
compensates for reduction ofpenetration depth due to hightemperature.
–Compatibility with core fueling
R. Sakamoto

National Institute for Fusion Science

b-101

23

Summary
Internal Diffusion Barrier (IDB) has been reproducibly obtained by using
intensive multi-pellet injection.
–Enables core plasma to access very high-density/high-pressure regime
Core diffusivity is kept at low level even highhigh-density
density regime–CoreQuasi stationary sustainment of high-density/high-performance plasma
has been demonstrated by using repetitive pellet injection.
–In order to extend operational regime to higher density, active divertor
pumping is required in addition to higher throughput pellet injection.
LHD experiment suggest the high density operation is suitable for helicalsystem.
–High density scenario enables a realistic reactor design which iscompatible with core fueling.
R. Sakamoto

National Institute for Fusion Science

b-102

24

3-8 Turbulent Transport and Zonal Flows

T.‐H. Watanabe
National Institute for Fusion Science /The Graduate University for Advanced Studies (Sokendai)Toki, Gifu, JAPANThanks to: H. Sugama, S. Ferrando‐Margalet, M. Nakata,
O. Yamagishi, S. Satake, K. Tanaka, H. Yamada, and W. Horton
1

Outline Introduction
 Zonal flows, ITG instability, GKV code

 Zonal flow response in tokamak and helicalplasmas GKV simulations of ITG turbulence in tokamak
and helical plasmas
 Recent results of gyrokinetic theory andsimulation studies at NIFS Summary and future directions
2

b-103

Zonal flows, ITG instability, GKV code

3

Zonal Flows in Nature
Zonal Flows in JupiterDifferential Rotation in Sun

SOHO/MDI, NASA/ESA

Cassini, NASA/ESA

b-104

4

Identification of Zonal Flow in
Fusion Plasma
HIBP System

HIBP#1
observation points

CHS zonal flow pattern
r1=12cm

90 degree apart
HIBP#2
observation points

out



c tr

Er

in

2

out

ExB flow



c tr

in

Poloidal Crosssection 1

0.5
1



C (r ,r )



1

0

Er
ExB flow-0.5

R=1m, a=0.2m

R=1m, a=0.2m
Poloidal Crosssection 2

-1
10

11

12
rradius
(cm)
2

13

14

A. Fujisawa et al., PRL 93 165002 (2004)

5

Zonal Flows and Turbulence inFusion Plasma Simulations
 Zonal flows have beenfound in various typesof plasma turbulencesimulations.
 A pioneering work by

Hasegawa & Wakatanifor zonal‐flow
generation
ti ini
turbulence (upper)
 Gyrokinetic simulationof toroidal ITG
turbulence by Lin et al.
(lower)Hasegawa & Wakatani, PRL 59, 1581 (1987).

Lin et al., Science 281, 1835 (1998).

b-105

6

Mechanism of Toroidal ITG Mode

7

Gyrokinetic Simulation Code, GKV
 Nonlinear gyrokinetic equation for perturbed ion

gygyrocenter
distribution f is numericallyy solved in thefive‐dimensional phase space, (x, y, z, v||, )


 
c
e
FM  C f   v||bˆ    v d     bˆ  f   , f   v   v d  v||bˆ 

t

v
B
Ti

|| 
0










 Adiabatic electron response, flux tube geometry.
 Electrostatic potential is given by the quasi‐neutrality
 HighHi h resolution
l ti off 5‐D
D phasehspace.



2 D

C
z

0A

b-106

F

B E

y
B

 8

9

Zonal Flow Response in Tokamak
99 ) derived a responsep Rosenbluth and Hinton ((1998)
function (kernel) of zonal flow in a tokamak.
 A residual zonal flow remains after the Landau‐
damping of geodesic acoustic mode (GAM).
Kk t   xk t  0x

1
1  1.6q 2  1/ 2

 The response function describes how strongly thezonal flow is generated by a given source term
 Standard benchmark test of gyrokinetic codes
10

b-107

GKV Simulation of Zonal‐Flow
Response in Tokamak

Cyclone DIII-D base case

 Zonal flow p
potential

asymptotically approaches
the residual level after theLandau damping of GAM.
 The damping rate agrees
with theory with finite kr[Sugama& Watanabe, JPP 2006].
g
trappedpassing11

Velocity‐Space Structures of f in
Response to Zonal Flow We have found that distributionfunctionfti consists
i t off twot parts,t (a)( )coherent and (b) ballistic
components.
Distribution Function

 The coherent part sustains theresidual zonal flow.
[Sugama & Watanabe, NF 2006]

b-108

12

Effect of Helical field on Zonal Flow Radial drift motion of helicalhelical‐ripple‐trappedripple trapped particles

leads to additional shielding effect of zonal flow.
 Gyrokinetic theory andpassingsimulation suggest
increase of zonal flow
responsepin theneoclassically‐optimized
helical systems.

trappedv dr bB

 Sugama & Wataanbe, PRL 2005
 Ferrando, Sugama & Watanabe,
PoP 2007Classification of particle orbits
in helical system

13

GK Theory of Zonal‐Flow Response
in Helical Systems
flow response by R.
H.
 Theoretical analysis of zonal
zonal‐flow
R.‐H.
has been extended to helical systems.
Long-time Response Function

 Reduction of helicalhelical‐ripple‐trappedripple trapped particle
particle’ss drift

improving the neoclassical transport also enhances
the zonal‐flow response !
Sugama & Watanabe, PRL 2005, PoP 2006

14

b-109

GKV Simulation of Zonal‐Flow
Response in Helical Systems( L = 2, M = 10 )

 Radial drift of helicalhelical‐ripple‐trapped particles
makes mean negative
part of f.

Long-Time Response
Kernel KL(t)Simulation( q = 1.5,

Velocity distribution function for
=8/13 at t = 6.23 R0/vti.
t = 0.1, kr ai =0.131 )Sugama & Watanabe, PRL 2005, PoP 200615

Higher Zonal‐Flow Response in
Inward‐Shifted LHD Plasma Parameters are taken from

LHD experimental results.
 Higher zonal‐flow response

is obtained for the inward‐
shifted LHD plasma which
h lowerhaslneoclassicall i lripple transport.
 A possible scenario of

turbulent transport
reduction in the I.‐S. case.

Watanabe, Sugama & Ferrando, PRL 2008
Ferrando, Sugama & Watanabe, PoP 2007

16

b-110

17

GKV Simulation of ITG Turbulent
Transport in Tokamak

 ITG turbulence and zonal flows with broad spectrum

in a statistically steady turbulent state
18

b-111

Confirmation of Entropy Balance in
Toroidal ITG Turbulent Transport Steady transport flux is obtained with the entropy

balance satisfied.
 Fine velocity‐space structures of f are generated in
the toroidal ITG turbulence.
19

Better Confinement found in
Inward‐Shifted LHD Plasma
Eexp/EISS95

shifted configuration of Inward
Inward‐shifted
LHD has better confinement
even with unfavorable field‐line
curvature (Yamada et al.).

100

Rax=3.6m
Rax=3.75m
Rax=3.9m

Reactorcondition
10-1

10-1

100

*b

<= Inward-shift<= Standard<= Outward<
Outward-shift
shift

101

 Not only the neoclassical, but also the anomaloustransport is improved in the inward‐shifted LHD
configuration.

b-112

20

Possible Scenario of Transport
Reduction for Helical Plasmas
 Inward‐Shifted LHD p
plasma is optimizedp
for reducinggthe neoclassical ripple transport.
 Slower radial drift motions of helical‐ripple‐trapped
particles lead to higher zonal‐flow response.
<= zonal‐flow response analysis
 Then, stronger zonal flows can be generated byinward‐shiftedcase
turbulence in the inward
shifted case.
 Thus, we expect anomalous transport reduction in the
inward‐shifted LHD Plasma.
The conjecture needs to be verified by
gyrokinetic simulations of turbulent transport.
21

Inward‐Shifted Case Shows Lower
Ion Heat Transport
 GKV simulation of ITG
turbulence for the
inward‐shifted caseshows reduction of theion heat transport bystronger zonal flows.
 ThisThi tendency
t disi
consistent with the
LHD experiments as
expected.

Time‐history of i obtained by the GKV
simulations of the ITG turbulence in the
LHD configurations.
(Watanabe, Sugama & Ferrando., PRL 2008)

22

b-113

Stronger Zonal flows are Generated
in Inward‐Shifted Configuration

GKV simulation results of electrostatic potentials at t=120(Watanabe, Sugama & Ferrando, PRL 2008)
23

Zonal‐Flow Structure is Clearly
Found in Inward‐Shifted CaseSpatio‐Temporal Profiles of the Zonal‐Flow Potential

24

b-114

25

Effects of Equilibrium‐Scale Er on
Zonal‐Flow Response
vdr
Radial drift ofhelically‐trapped
particles

Orbit of helically‐trappedhelically trapped
particles modified by Er

vEXB
E

Er

B
Flux
surface Equilibrium‐scale Er field

generates an ExB component
to velocity.
 The poloidal ExB rotation with
reduced radial displacement
E will decrease the shieldingof zonal‐flow potential andincrease its response !
(Mynick & Boozer, PoP 2007)

b-115

26

GK Theory of Zonal‐Flow Responsewith Equilibrium‐Scale Er Equilibrium
Equilibrium‐scale
scale Er associated with the neoclassicaltransport in helical systems also enhances zonal flows.
 Shielding of helically‐trapped particles with poloidal
angular frequency  = ‐ cEr/rB is given by

ll
l
l
l
l fl response Collisionlesslong‐time
limit
off zonal‐flowkernel:Sugama, Watanabe & Ferrando, PFR 2008

27

Extension of GKV Code to
Poloidally Global Model GKV code is recently extended to the poloidally global

model for studying the Er effect on zonal flows inhelical systems.
 Flux coordinates (T, , ) with  = –
 Field‐line label dependence of |B|
B  B0 1   t (r ) cos   2    l (r ) cosl  (l 2  M ) 
 Gyrokinetic equation for zonal flows with Er

e
 

 
FM
  v||bˆ    ik r  v d   bˆ  f  ik r  v d
t
v

Ti



||







28

b-116

GKV Simulation of Collisionless
Zonal‐Flow Damping with Er GKV simulation ofcollisionless zonal‐flow
damping with Er has been
carried out.
 Equilibrium‐scale Ercontributes toht off zonall flow
flenhancement
response after the initial
GAM damping.

Time‐history of zonal flow
potential for different Er.

29

Linear Gyrokinetic Stability Analysis
by Using GOBLIN Codey of Electrostatic Linear stability(drift wave) /electromagnetic(MHD‐like) modes can beinvestigated.
 Electrons/ions (circulating,trapped) can be treated with thesame computation load (eigenvaluecode).
 Complicated magnetic
configuration (helical/shaped
tokamak) with various n/T profiles
can be treated.
[by O. Yamagishi]

b-117

3

γ/ω*e
ideal MHDkθρthi=0.4
2

KBM
1

ITG

TEM
0
0

0.02

0.04 βtot30

Transition of ETG Vortex Structuresand Electron Heat TransportdS/dt eQe
dWp/dt Dc

 Reduction of turbulentt = 90t = 320

Ttransport associated with
self‐organized vortex
structures is found in
gyrokinetic simulations ofslab ETG turbulence.

31[Nakata, Watanabe, Sugama & Horton, APS/DPP 2008]

Drift Kinetic Simulation of GAM
Oscillation in LHD Plasmas
Rax=3.52

 Dependence of GAM on Rax

 Higher‐(m,n) components ofB spectrum, also enhance
GAM damping on outer flux
surface.

real freq. ω/ω0

damping rate γ/ω0

is
drift
i comparedd betweenbd if
kinetic transport code
(FORTEC‐3D) and the analytic
formula.
 VMEC equilibrium is used.
 Inward shift ⇒ lower GAM
frequency & higher damping
rate
rate.

Rax=3.62

ρ=0.26b-118

ρ=0.66

1

1

1

0.8

0.8

0.8

0.6

0.6
6

12

18

0.6
6

12

18

6

12

18

Number of Fourier components
Rax=3.52
0.1

ρ=0.26

Rax=3.62
0.2

Rax=3.77

ρ=0.51

ρ=0.66
0.2

0.05

0.1
0.1

0

Satake, Sugama &Watanabe, NF 2007

Rax=3.77

ρ=0.51

6

12

18

0

6

12

18

0

6

Number of Fourier components

12

18

32

33

Summary We have investigated ITG turbulent transport andzonal flows in tokamak and helical systems:
 GK theory of zonal flows and GAM is successfully

confirmed by GKV simulations.
 GKV simulations fully resolving df in 5‐D phase space
made the first step in simulation studies of turbulent
transport in LHD plasmas.
plasmas Coupling of the neoclassical and anomalous transport

through zonal flows appears in helical systems.
 The synergetic studies of theory and simulation should
be further promoted.

34

b-119

Collaborations with LHD
Experiments and other GK groups = 1 .7 7 m ms2

 Preliminary comparison

PreliminaryyKys ~ 0.4

1

N o is e L e v e l

0 .1

2D‐PCI Measurement(K.Tanaka et al.)0 .0 1en at 

100 .0 1

0 .1
k 
y

1

with experiments Collaborations with LHD
experimental group will
be further promoted.

s

=0.6

Kyi~00.2‐0.3
2‐0 3

 International
I t
ti
l

collaborations forbenchmarking helicalgyrokinetic codes are in
progress.

GKV

35

Future Extensions of GKV Code Introduction of geometry and equilibrium parametersthat are more relevant to LHD experiments
 ITG turbulence simulation with equilibrium radial
electric field => Isotope effect Electron dynamics
 ITG/TEM turbulence with non‐adiabatic electron

response Effects of finite‐collisionality
 ETG turbulence in helical plasmas

 Development of global gyrokinetic simulation code
36

b-120

3-9 Development of long-life liquid blanket

Development of long-life liquid blanket
Takuya Nagasaka
NIFS-FERC staff: Akio Sagara, Takeo Muroga, Arata Nishimura,
Yosimits Hishin
Yosimitsu
Hishinuma,
ma TerTeruyaa Tanaka
Tanaka, Masatoshi Kondo

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

1. Introduction: NIFS and Japanese universities
focus on liquid breeder blanket
2 / 34

Type

Solid
S lid
breederblanketLiquidq
breederblanket

T breeder

Coolant

Structure

ITER-Day-1st TBM

DEMO design

Li2TiO3 etc.

H2O

RAF steel

WCSB (JP)A-SSTR (JP)Li2TiO3 etc.
etc

He

RAF steel

HCSB (JP(JP, EU
EU, KO)

Li2TiO3 etc.

He

SiC ceramic

DREAM (JP)A-HCPB (EU)ARIES-I (US)

Flibe

Flibe

RAF steel

FFHR (JP)

Flibe

Flibe

V alloy

Li

Li

RAF steelLi

Li

V alloy

FFHR-LV (JP)ARIES-RS (US)

Li-Pb

H2O

RAF steel

WCLL (EU)

Li-Pb

He

RAF steel

Li-Pb

Li-Pb

RAF steel

ARIES-ST (US)

Li-Pb

Li-Pb

SiC ceramic

TAURO (EU)ARIES-AT (US)Organizationin Japan

I-HCPBI HCPB (EU)

JAEA
Universities

FFHR-FV (JP)HCML (KO)HCLL (EU)DFLL (CH)HCML (KO)Collaboration

NIFS

DCLL (EU)

Water-cooled solid breeder (WCSB) blanket is recognized to be the most feasible with the current technology
The other blankets are more attractive for power plant, but require more database and challenging
technologiesb-121T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Liquid breeder blanket can be simple, and provide
thermal efficiency and operation efficiency
 Simple structure

Fuel line

T breeder itself can becoolant in liquid breeder
blanket On-time control of breeder Purity and composition ofbreeder is controlled outside
the blanket
 Li is continuously supplied
outside blanket during
operation
 High thermal efficiency andti efficiency
ffi i
ibl
operation
are possibleT extractor

T
T
Plasma3 / 34Heat exchanger

6Li + n  3T + 4He

Purifier Key technology

Consistency of T extraction
with heat exchange Purification
 Materials
Li supplier

T Breeder = coolant
Flibe / Li / Pb-Li

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Energy conversion efficiency is determinedby material operation temperature
4 / 34
Possible energy conversion efficiency
50
DREAM

Converrsion efficiency / %

AGR

40



FBR
PWR

HTGR
FFHR

30

 Possible energy conversion

SSTR
BWR
RAF steel

ARIES-1
SiC ceramic

V alloy




He

20

Flibe, Li, Li-Pb
Water



Data from M. Enoeda & A. Sagara

200 300 400 500 600 700 800 900 1000
Coolant temperature / oC

b-122

efficiency of blanket is increased
with
ith coolant
l t ttemperaturet
Liquid breeder blanket can obtainhigher efficiency than watercooled blanket
Coolant temperature is limited byoperation temperature forstructural materials
RAF steel is the 1st candidate
because of its industrial maturity
V alloy and SiC ceramics arerecognized as advanced
materials for higher efficiency
blanketT. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Material design window defines the operation
temperature and lifetime of blanket
5 / 34

 Design window shows possible

RAF steel

1400
Temperature / oC

1200
1000

Void swelling600



He effect (?)

FFHR, SSTR

400
200
0

Temperature / oC

Thermal creep life

800

0He effect (?)
Brittle fracture by irradiation
2 4 6 8 10 12 14 16 18 20
Time / yr (1 yr = 1 MW a m-2 = 10 dpa)

1400

V alloy

1200

Thermalhl creep life
lif

1000




Void swelling
He effect (?)

800
600



ARIES-RS

400
200
0

Brittle fracture by irradiation0

2 4 6 8 10 12 14 16 18 20
Time / yr (1 yr = 1 MW a m-2 = 10 dpa)

operation temperature andlifetime for low activationmaterials
The possible operation conditionis enclosed by the following
material properties
Higher limit temperature Thermal creep
 He effect Void swelling
Lower limit temperature Brittle fracture by irradiation
Followings are potential limitation,
but not included in the current
design window Brittle fracture at welds
 Material corrosion by coolant

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

2. Purpose and contents
6 / 34
NIFS-FERC have been focusing on the liquid breeder blanket
Low activation material

Liquid breeder

RAF steel

Flibe

V alloyLi

SiC ceramic

Pb-Li

Collaboration with
Kyoto university andTokyo Institute of Technology

In order to develop long-life blanket, the following researches are ongoing
Limitation for operation temperature and lifetime

Main work of NIFS-FERC
 Today’s talkRAF steelV alloy

Thermal creep

Ongoing

Ongoing

H effect
He
ff t

IFMIF

IFMIF

Void swelling

Universities

Universities

Ductility loss by irradiation in weld metal

JAEA

Ongoing

Corrosion by Flibe / Li

Ongoing

Ongoing

Purpose of the present study
 To evaluate material property
 To clarify mechanism for property degradation and improvement
 To obtain guiding principle for long-life materialb-123

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

3. Welding: Large-heat projects of RAF
steels and V alloys lead to welding study
7 / 34

 Blanket construction requires various shape product fabrication (plate, tube and rod)

and welding technology for low activation materials

 Large-heatLh t projects
j t provided
id d ththese products
d t tto world
ld iinstitutes
tit t ffor R
Round
dR
Robin
bi tteststincluding welding study Large heat more than 100 kg in the world

1990

We are here

2000

2010

F-82H, JLF-1, Fe-8~9Cr-2W-0.1C, JapanRAF steelEUROFER, Fe-9Cr-1W-0.1C, EU
US832665, US832864, V-4Cr-4Ti, US-DOE
V alloy

NIFS-HEAT-2, V-4Cr-4Ti, NIFS-FERC
V-4~8Cr-4~5Ti, A. A. Bochvar Inst., RF NIFS-FERC have been taking part in the Round Robin tests for RAF steels NIFS-FERC promoted an initiative for large-heat project of V alloy

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

High purity metal vanadium was developedfor V alloy large heats
8 / 34Oxygen and nitrogen impurity in V alloy large heats400

 Carbon, nitrogen and oxygen

Oxygen / wppm

US832864-Ingot
300

US-Pure V

200

NH1-Ingot



NH2-Ingot

100

0



Developed
JP-PureV
0

100
200
300
Nitrogen / wppm

166 kg ingot of NH2



Plates and rods
26t
1.9t

100 mm

400

1.0t

(mm)

4.0t

6.6t
0.5t

0.25t
2
8

b-124



were well known to degrade
variouspropertiesiti off vanadiumdiand its alloys
NIFS-FERC developed metal
vanadium with low oxygen levelin industrial scale melting size
NIFS-HEAT-1 (NH1) and NIFSHEAT-2 (NH2) ingots were
fabricated from the developed
vanadiumdiVarious products, such as plates,rods and tubes, have been
distributed to world institutes forRound Robin tests
NIFS-FERC initiated welding
studies with the NIFS-HEATs

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

NIFS-HEAT-2 was welded in high purity Ar
flow to avoid impurity contamination

9 / 34Laser welding robot system

NH2 Weld Welding box with 6N-grade

Ar flowCross section

Hiroshima Univ.

Welding box

Impurity(wppm)
BM

WM

C 51

49





N 123 129
O 139 158

1 mm

(99.9999%) Ar flow wasdevelopeddld ffor welding
ldi off V alloyll
to avoid impurity contaminationfrom the air
Base metal (BM) and weld metal(WM) was chemically analyzed
on C, N and O
It was confirmed that noremarkable contaminationd during
d i welding
ldi
occurred
Tensile strength, bending ductility
and fracture energy of WM werecomparable to BM
In order to estimate irradiation
property and material lifetime,
fracture energy is important

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Fracture energy of weld metal was much
improved by oxygen reduction
Impact load

Impact fracture test

10 / 34

 Absorbed energy for fracture ismeasured in impact fracture tests

 Brittle fracture with low fracture
Fracture energy: absorbed energy for fracture

Fracture energy / J cm-2

NIFS-HEAT-2, Laser

150
100

BrittleLow fracture energy

Fracture energy of weld metal

200

Lab. 200 g scale
Lab
scale,
Arc

50
00energy is induced below theductility limit

DuctileHigh fracture energy

V-4Cr-4Ti
RT testDuctileFracture-resistant

NIFS-HEAT-1, Arc

Ductility limit

BrittleWeak to fracture

100
200
300
Oxygen impurity/ wppm

 Welding of US alloy was

impossible, because of low
fracture energy
 Oxygen impurity reduction in
NIFS-HEATs made welding400
possible

US, Arcb-125

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Oxygen is released into weld metal bydecomposition of Ti-O precipitates
Vickers hardness, H / Hv

Hardness distribution around weld bead
200

NIFS-H EAT-2
W eld
ld metalt l

150
Base metal-505Displacement from bead centreline, mm

BM

WM

11 / 34

 It is well known that solid solution

hardening by impurity O inducesb ittl ffracture
brittletiin V alloysll In base metal, the impurities arestabilized as Ti-O precipitates During welding, the Ti-O
precipitates are decomposed, andwent into solution in weld metal The released oxygen, induces
hardening and brittle fracture in
weld metal of US alloy

WeldingBM
O Ti O

Ti-O precipitates

WM
O

Ti
O

500 nmT. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Degradation of fracture energy was enhanced in weld metal,
and was recovered by post-irradiation annealing
12 / 34

Fracture energy / J mm-3

Fracture energy of weld metal
after neutron irradiation

0.5 Un-irradiated

Weld metal

0.3

0.1
0

TargetBase metal

0.4

0.2



Ductility limit
V-4Cr-4Ti
RT test0

Recovery0.1
1
10
Irradiation dose / dpa



100


Irradiation temperature: 290 ~ 450 oC
Irradiation facility: JMTR, JOYO (JP), HFIR (US)
1 dpa ~ 5 x 1024 neutrons m-2

b-126



Resistance to 100 dpa irradiation was
expected for low activation materials
100 dpa is roughly 10 yr lifetime (netoperation year under 1 MW m-2) for
blanket materials
Base metal maintained high fractureenergy up to 8.5 dpa
 Excellent resistance to neutron
irradiation
Weld metal maintained high fractureenergy after 0.98 dpa irradiation
 This is big progress in welding of
V alloy
However, it became brittle at 8.5 dpa
 Brittle fracture was enhanced inweld metal
Ductility of weld metal was recoveredby post-irradiation annealing at 600oC
for 1 hr

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Degradation of fracture energy was induced byaccelerated irradiation hardening in weld metal
13 / 34

Irradiation hardening, Hv

300

 It is well known that irradiation

Hardness / Hv

Recovery
+22%

+39%

+19%

200
Hv

Unirrad.
100

BM o WM BM oWM BM o WM WM
290 C
400 C
450 C
0.08 dpa
0.98 dpa
8.5 dpa
Irradiation defects in weld metal (290oC, 0.08 dpa)

200 nm50 nm

hardening induces brittle fracture In all the irradiation conditions,

irradiation hardening in weld
metal was 19~39 % larger thanbase metal
 Irradiation hardening is causedby irradiation defects, anddescribed by Orowan’s modelHv C Mb

Nd

C: Constant = 3/9.8 Hv / MPa
M: Taylor’s constant = 3
FixedShear modulus = 46.7 GPab: Burgers vector = 0.26 nm
: Strength of defect
N: Number density of defects Variable
d: Defect size ~ 5 nm

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Irradiation defects are more stable tothermal decomposition than base metal
14 / 34
BM, As-irrad.

400oC

500oC

600oC

700oC

WM As
WM,
As-irradirrad.

400oC

500oC

600oC

700oC

200 nmb-127

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Degradation of fracture energy was induced byaccelerated irradiation hardening in weld metal
15 / 34

Irradiation defectBase metal

 Irradiation defects in weld metal

Weld metalO
O

デ
Hardening, H
Hv / HvO

Recovery of irradiation hardening
タ by post-irradiation annealing//

Cal. from visible defect80
NIFS-HEAT-2
Experimental
70
WM
60
BM
50
40
30
20
10
0
As-irrad. 500oC 700oC 400oC 600oC
o
400oC
600 C As-irrad. 500oC
700oC

was more stable to thermal
decomposition
 It was clarified that defectstrength, , was 25% higher in
weld metal than base metal
 It is considered that defectstrength is increased bydecoration of oxygen atoms in
weld metal
 20~30 % of the hardening isunderstoodd t dbby th
the visiblei ibl ddefectsf t
 Invisible (< 5 nm) defects or
impurity precipitates areindicated Further investigation
 Example: Defects or
precipitates with 1 nm and 1
x 1023 m-3

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Irradiation hardening can be suppressed by postweld heat treatment before neutron irradiation

16 / 34300

PWHT effect on Irradiation hardening

Hardness / Hv

Welding  Irradiation+39%

Welding  PWHT  Irradiation

600oC

200

950oC
Hv

Unirrad.
100

BM o WM
290 C
0.08 dpa

WM

WM

Without PWHT

With PWHTOOTi

O Ti O
Ti-O precipitate by PWHT

b-128

 Fracture energy degradation in

weld metal was caused byacceleratedl t d irradiationi di ti hhardeningd i The irradiation hardening in weld
metal was suppressed by postweld heat treatment (PWHT)
above 600oC
 Solid solution oxygen in weld
metal is precipitated out by
PWHT, and does not formd f t
defect-oxygen
clusterl t anymore Further irradiation tests areplanned to confirm theimprovement of fracture energy
by PWHT before neutron
irradiation

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Summary of welding study
17 / 34
 NIFS-FERC promoted an initiative for large-heat project, NIFS-HEAT-1 and -2, which enabled welding study Welding of V alloy became possible by reduction of oxygen impurity
 Weld metal of V alloy exhibited resistance to neutron irradiation up to 0.98

dpa (0.1 yr in 1 MW m-2), while it was brittle at 8.5 dpa

 One of mechanisms of the brittle fracture was accelerated irradiation

hardening by oxygen and irradiation defect interaction

 Suppression of irradiation hardening was demonstrated by post-weld heat

treatment (PWHT) before irradiation, which will improve the ductility ofneutron-irradiated weld metal further

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

4.

Corrosion: Blanket condition is a combinationof flowing and temperature gradient
18 / 34
Flowing Flibe, Li

Static Flibe, Li

Saturated
layer
Corrosion
layer

Material

Flowing Tests
Saturated layer removed

Static Tests
Qualitative tests- No saturation ofdissolution- HighHi h velocity
l it
Mechanical removalof corrosion layer
 Erosion- Dissolution at hot-leg- Precipitation at cold-leg
 Mass transfer from hot
hotleg to cold-leg

Flowing Flibe, Li

Hot-leg
Cold-leg
Flowing Test with Temperature GradientBlanket condition tests
 Static tests provide fundamental corrosion mechanism Blanket condition requires both flowing and temperature gradientb-129

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

NIFS-FERC is starting material corrosion test
under flowing conditions
19 / 34

Molten salt Flibe

Liquid metal Li

Static pot test
∆T=0 [oC]
V=0 [m/s]

2 cc
Fluoridation
Electrochemical corrosion

100 ccLiquid metal corrosion
Decarburization

Today’s talkNatural convection
loop test∆T = 50～100 [oC]
V= 0.01～0.05 [m/s]200 cc+ Mass transfer

700 cc+ Mass transfer

We are here

Forced convection
pot test∆T=0 [oC]]
V=0.1～1 [m/s]

100 cc+ Erosion

Forced convection
loop test∆T = 50～100 [oC]
V=0.1～10 [m/s]

100 L
Pomp
+ Mass transfer+ Erosion

100 cc+ Erosion

試験片

内筒

試験片

内筒

Do

DH

Do

D
m

DH
b

Gas line filter

D
m

b

l

l

D

D

D/3

D/3

Expansion tank

CoolerTest section

10 L+ Mass transfer+Erosion

HeaterForced convection loop is required for blanket condition test
NIFS-FERC is making step-by-step approach by using natural convection loop and forced
convection pot

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

NIFS and The University of Tokyo has established Flibe
purification system in Japan

20 / 34

Corrosion agent Source and typical amount

Purification process

HF(1) T generation
Li + n  T + He
T+ + F-  TF ~ 30 ppm / day(2) Initial loading impurity ~ 200 ppm

REDOX (REDuctionOXidation) control
2TF + Be  BeF2 + T2

O

Initial loading impurity > 500 ppm

HF bubbling
BeO + 2HF  BeF2 + H2O

Ni, CuInitial loading impurity ~ 10 ppm

H2 flowing
MxFy + y/2H2  xM + yHF

Fe Cr,Fe,Cr W(1) Initial loading impurity
imp rit ~ 10-100
10 100 ppm
H2 flowing
flo ing(2) Dissolution from RAF steel > 100 ppm MxFy + y/2H2  xM + yHF

 HF reduction in Flibe by REDOX control has been successfully demonstrated in USA

by JUPITER-II program (Japan-USA Program of Irradiation Test for Fusion
Research)
 In order to reduce initial loading impurities, NIFS has established Flibe purification
system in Japan by the collaboration with The University of Tokyo

b-130

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

High purity Flibe has been successfully produced
21 / 34
High purity Flibe High purity LiF and BeF2 weremelted in high purity He gas

 The composition of Flibe was

2LiF + BeF2

 Purified by HF gas bubbling andH2 gas flowing at 600 oC
 Oxygen reduction
2HF + BeO  BeF2 + H2O
 Metal impurity reduction
MxFy + y/2H2  xM + yHF
 Fe impurities were successfully
reduced to 3-10 times lower than
Impurity level for Flibe (wppm)
Test capsulethe conventional Flibe
Fe Cr W Ni Cu
 It is necessary to confirm if thepurity is enough for initial loading
Flibe #1, 50 g
43
<1
to blanket
Flibe #2, 50 g
4
13 <1 <1 <1 Corrosion tests were started from
Flibe #3, 150 g 23 5
4
static pot test
Petti, US, 2006 260 16

15

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

NIFS-FERC has established Li corrosion test
facility by collaboration with TYK Co., Japan
Li corrosion test facility in TYK Co.

22 / 34

 Li exposure test has been

performed on V alloy in USA by
JUPITERII program and USUSJUPITER-II
DOE program Li technology is also expectedfrom IFMIF
 Li flowing test in 316SS loop
has been conducted in
Osaka University, Japan by
IFMIF-Key Element
Technology Phase activity
 NIFS-FERC
NIFS FERC initiated Li exposure
test on RAF steel to investigate
the feasibility of RAF steel-Li
blanket as proto-type of V alloy-Li
blanket Flowing corrosion test is starting
in NIFS-FERC

Ar grove box
Furnace

Test capsuleLi natural convection loop in NIFS

b-131

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Corrosion rate of JLF-1 below 600 oC was lessthan 10 m/yr at static condition

23 / 34

Corrosion of steels in Flibe, Li and Na Weight loss of JLF-1 in Flibe andWeight loss, m / g m-2

Li was similar to that of 316 SS in
liquid Na (FBR cooling system) The present Flibe and Li is
expected to be enough pure for10
the initial loading to blanket
316 SS-Na
JLF-1-Flibeo
Future work
JLF-1-Li 316SS-Flibe
600 C
550oC
o
o
600
C
 Corrosion test under flowing
600 C
5
500oC
500oC
condition
500oC
 Large-scale purification0 Real time impurity sensor
0
500
1000
1500
2000
2500
Na data:Time, t / hrand purification under flowing
Ganesan, 1998
JLF-1 sample
JLF-1 sample  On the other hand, corrosion wasNi
crucible
JLF-1 crucible
enhanced by more than 10 times,
when …
Flibe
Li
Flibe
Mo
 JLF-1 contacts Ni in Flibe Li is contaminated with N
15

JLF-1-Flibe((Ni crucible))
JLF-1-Li
550oC(+ 0.5 % N)
Corrosion rate < 10 m/yr
600oC

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Base corrosion mechanism in Flibe is corrosion
product formation and its dissolution

24 / 34

550oC x 2003 hr, Ni crucible
Flibe
JLF-1
plate
Analyzed line
SEM-EDX, Fe

Corrosion product
JLF-1
plate

20 m

Flibe

10 m

Lower
concentration

Cr
WC

Segregation

W Corrosion products were observed at the surface of JLF-1
 Cr showed selective dissolution
 W was segregated at the edge of the plateW is expected to be resistant to Flibe, and its coating will be effective to corrosionb-132

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Dissimilar metal contact enhances Fe transfer byelectrochemical corrosion

25 / 34

 Ni metal is nobler in Flibe than

Fe2+

JLF-1 sample

Current, I

Ni crucible

Fe, because formation freeenergy of fluoride is larger
 Contact of Ni and Fe produces
electrochemical corrosion
Free energy of fluorides

Flibe
550oC x 2003 hr

SEM-EDX, Fe

SEM-EDX, Fe
Fe layer

Fe transfer

200 mLoss of carbon from the surface occurred inLi, but is limited in 100 m for 10 yr

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

26 / 34

７００℃ 100 hr

Before exposureFeCc

C depletionaaaMartensite (bct)aaFerrite (bcc)

10μm

10μm

(wt%)
MaterialsComposition

C

Cr

W

Before exposure

Fe-9Cr-2W-0.1C

0.09

8.92

2.00

700ºC 100h

Fe-9Cr-2W-0.1C

0.03

8.88

1.95

Phase transformation
100m from the surface

Base corrosion mechanism in Li is liquid metal corrosion (alloying in liquid phase)
It was found that phase change (Lattice structure change) from martensite to ferrite occurred byloss of the carbon at the specimen surface
Ferrite phase formation may induce degradation of strength, but is not critical because thedepth is estimated as 100 m after 10 yr
On the other hand, N contamination enhanced weight loss by intermetalic compound formation
 2Li3N + Fe  Li3FeN2 + 3Li, 5Li3N + Cr  Li9CrN5 + 6Li: Purification control is necessaryb-133

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Summary of corrosion study
27 / 34
 From the static corrosion test, corrosion rate of JLF-1 in Flibe and Li wasless than 10 m/yr
 Typical wall thickness in blanket is ~ 5 mm
 Assuming 1 mm corrosion is acceptable, 100 yr is lifetime

 Corrosion mechanisms were investigated

Flibe: Corrosion products formation, electrochemical corrosion
Li: Liquid metal corrosion, carbon loss, intermetalic compound formation

 Corrosion tests under flowing condition are starting

Generally, lifetime for corrosion is decreased under flowing condition
NIFS-FERC is making step-by-step approach by using naturalconvection loop and forced convection pot
 Forced convection loop is necessary for corrosion test under blanket
condition

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

5. Thermal creep: Creep test simulate longterm deformation in blanket condition 28 / 34
 Typical stress for structural

Tensile test:
1~5 min

Creep test:
1 day~1 yearLoad, Px

Displacement,x

Load, Pdx/dt = const.
P = f(x)P = const.
x = f(t)b-134

material is less than several 10
MPa
For that stress level, lowactivation materials are deformed,
but the deformation is fully
recovered if the stress isremoved in short time
If the stress is kept for long time,the deformation is increased, andfinally the material is fractured
 This is creep deformationand fracture
The typical creep deformation
rate is as slow as 0.01~1 %/day
Creep lifetime determines theupper limit for operation
temperature of blanket

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Blanket operation temperature and stress isdetermined by creep fracture of materials29 / 34
Fracture map by theories

 Several GPa is necessary to

fracture materials by atom bonddestruction~ 10 GPa  Materials are fractured by much
Atom bond destruction lower stress because of defects
 Crack
Impact test
~ 1 GPa
Tensile test Dislocations (line of crystal
defects)~ 100 MPa
 Fracture limit for blanket
temperature range is determined~ 10 MPa
Creep test CreepC
ffracturetby creep fracture Blanket operation stress is set in~ 1 MPa No fracture area
 Or, enough long-life (> 10 yr)
Fracture limit~ 0.1 MPa
area for creep fracture

Blanket temperature for RAF steel & V alloy

No fracture

M. M. Li & S. J. Zinkle, 2007

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Acceptable stress of JLF-1 for 11.4 yr-lifetime was estimated as
135 MPa at 550oC, and was slightly affected by aging
Typical creep deformation curveStrainn(Deforma
ation)

εRupturep(Fracture)Mini. Creep Rate
Rupture Time(Lifetime)
PrimaryTime

Tertiary

Secondary

Acceptable stress analysis for 11.4 yr in lifetimeno ageing
550oC/2000h
600oC/2000h
650oC/2000h
700oC/100h

Applied stress, MPaa

300
260



220
180

JLF-1



140
100

550oC/100000 hr-lifetime
24

25

26

27

28

29

L-M parameter, LMP=T(30+logtr)x 10-3

b-135

30 / 34

Acceptable stress for 100000 hr (11.4yr)-lifetime is required for design ofblanket11.4 yr is too long to test everything
Usually, the acceptable stress is
extrapolated from shorter creep test
data than 10000 hr (1.14 yr).
NIFS-FERC has started thermal
creep study with the shorter test
Data from ~500 hr (~ 20 day)-test isavailable at this moment
From the data, acceptable stress of
JLF-1 for 11.4 yr-lifetime wasestimated as 135 MPa at 550oC
 Longer test is undergoing
Effect of thermal aging at higher
temperature was also investigated The contribution of the aging was
limited in +/- 15 MPa

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Creep test on V alloy under Li condition was
performed by creep tube
31 / 34
Creep tube filled with high pressure He

 Tubing of V alloy became

possible because of workability
improvement by reduction ofoxygen impurity
After Li
800oC, 90 MPa,  Creep tube test is popular in
428 hrsteels for creep test underirradiation condition, where noloading mechanism is available+10 mm+5 mm
 Tube is filled with high0pressure He at room
-5 mm
30
temperature-10 mm He pressure is increased byincreasing temperature0 Hoop (expansion) stress by
He pressure produces creep
30
deformation
VPB3
 Creep tube is also useful forcreep test under Li condition

Before LI

29 mm

Tube ddiameter / mm

Laser welding

90
120

5
4.8
4.6
4.4
4.2
4

60

Before Li
After Li

150
120

60
90

Diameter change of creep tube

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Creep test on V alloy under Li condition was
performed by creep tube
32 / 34


Creep rate of NIFS-HEAT-2
800oC

Uni-axial, after 428 h -Li
Uni-axial, vacuum
Tube, vacuum

10

-2

10

-3

10

-4

10

-5

Uni-axial,
vacuum10-6

1 % - 105 h

10-7Creep rate / h

-1

Weak

StrongTube, in Li

Tube, in
i Lii

50

700oC

750oC

Log log plot
Log-log

100
200
Stress / MPa

300







Uni-axial creep test

Creep tube testb-136

Tube test exhibited larger creep rate
than uni-axial test Hoop stress estimation maybe
smaller Stress calculation analysis
 Bi-axial stress may enhance
creep deformation
 Investigation of deformation
mechanism
Creep deformation is enhanced in Li
condition
 It was found that oxygen impurity
transfer from V alloy to Li
degraded creep rate
Oxygen impurity increased creep
strength It is a trade-off between creep
strength (high O) and ductility(Low O)
Assuming 1 % deformation isequivalent to fracture, acceptablestress for 100000 hr (11.4 yr)-lifetime
was estimated as 90, 70, 40 MPa at
700, 750 and 800 oC, respectively

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

Summary of thermal creep study
33 / 34
 Acceptable stress for 100000 hr (11.4 yr)-lifetime was estimated from shorter

creep test
 JLF-1: 135 MPa at 550oC
 NIFS-HEAT-2: 90 MPa at 700oC, 70 MPa at 750oC, 40 MPa at 800oC
 Longer time tests are ongoing to confirm the obtained acceptable stress Mechanism of creep deformation is being investigated to understand thedifference between uni-axial and tube test condition, and between
vacuum and Li environment

 Improvement of creep property is being tried to increase lifetime andoperation temperature Advanced work hardening process Example: Hardening by TiO2 precipitates in V alloy Strengthening element addition
 Example: High Cr- V alloy, Nano-particle-dispersed V alloy

T. Nagasaka, Review meeting, Dec. 13 / 2008 , Takayama

6. Summary
34 / 34
















NIFS-FERC promoted an initiative for V alloy large-heat project, NIFS-HEAT-1 and -2.
Welding of V alloy became possible by reduction of oxygen impurity. Weld metal of V alloy exhibited
resistance to neutron irradiation up to 0.98 dpa (0.1 yr in 1 MW m-2).
From the analysis on the mechanism for irradiation effect,effect it is believed that higher irradiation resistance isobtained by appropriate post-weld heat treatment before neutron irradiation.
NIFS-FERC established corrosion facility for Flibe and Li
From the static corrosion test, corrosion rate of JLF-1 in Flibe and Li was less than 10 m/yr. Fundamental
corrosion mechanisms were clarified.
Forced convection loop is necessary for corrosion test under blanket condition. NIFS-FERC is making stepby-step approach by using natural convection loop and forced convection pot.
NIFS-FERC has been started long-term creep test to investigate thermal creep of low activation materials.
Acceptable stress for 100000 hr (11.4 yr)-lifetime was estimated from shorter creep test. Longer time tests are
ongoingg g to confirm the obtained acceptablepstressMechanism of creep deformation is being investigated to understand the difference between uni-axial andtube test condition, and between vacuum and Li environment.
Further improvement of creep property is being tried to increase lifetime and operation temperature
For long-life blanket, the above long-life material technology will be integrated with the other research activity
in NIFS-FERC and universities.
 Coating study: MHD coating, T permeation coating, Unti-corrosion coating, 1st wall coating Thermofluid study Tritium study
As a result of the integration, we really hope blanket mock-up in futureb-137

b-138

4.

Resume of NIFS Special Review Meeting

Dec 13, 2008 (Sat.) 8:30 - 17:30
Special Conference Room 3F, HIDA Earth Wisdom Center, Takayama, Gifu, Japan-

Reviewers: (w/o title of honor)
C.Alejaldre, G-S Lee, H.Takuma, J.W.Van Dam, K.Nishikawa, M.Tendler, R.Wolf, S.Itoh,
T.Klinger,-

NIFS members:
O.Motojima, S.Sudo, A.Komori, H.Yamada, S.Imagawa, N.Nakajima, S.Okamura, M.Sato,
A.Sagara, S.Sakakibara, R.Sakamoto, M.Yokoyama, T.H.Watanabe, T.Nagasaka, Y.Kainai

Self-introduction by each member
chaired by S.Sudo

Presentation by S.Sudo: Introduction of NIFS activities
Van Dam: What are activities of Public Relation office ?
Sudo:

We started many years ago, For citizens, PR office assists in their visits to the institutewith appropriate explanation, NIFS web server, and recently Kids Science Museum has
started. I think it has been working well . Do you have additional comments, Sato sensei?

Sato:

I will explain later about it, such as on science communication.

Tendler: In relation to Deuterium experiments, PR is very important. What is near-term plan?
Sudo:

In addition to the PR office, a special team led by Komori has been making the generalexplanation of DD experiments to citizens with many town meetings and the negotiations
with local governments. This team is prepared separately from the PR office because of thespecial importance of the DD experiment campaign.

Alejaldre: In ITER, we have a special division for safety. I’m happy to help you on this regard. Do
you have collaboration with Naka for ITER-related matter?
Sudo:

In NIFS, we have an internal group for ITER-related works. We also established the
Rokkasho research center for ITER-related subjects. We will soon have a room at thebuilding in Rokkasho and relation with ITER will go ahead.

Motojima: We have formal regular meetings 3-4 times per year with JAEA. Collaboration with
JAEA is included in the NIFS collaboration program.
Klinger: For bilateral collaboration. What is important to you about QUEST ?
Komori: Construction of the QUEST is completed this March. First plasma was produced in June.
They use already OH and rf current drive. For bilateral collaboration, NIFS is a center ofUniv., and NIFS is controlling all budget and experimental plan. For QUEST, Kyushu Univ.

b-139

proposed machine and we discussed the plan and made decision for the construction andall-Japan structure.
Motojima: On the process, I should mention Emeritus Prof. Itoh's decision to shutdown TRIAM-1M
to make the start of new experiment possible.

Presentation by A.Komori: Large Helical Device (LHD) Project
Klinger: It is nice to see you are approaching to closed divertor design. What is the status of design
work and future plan? Will you stop the experiment for the installation?
Komori: Design study has been almost completed. New design will be made within next year.
Klinger: Do you plan to stop machine?
Komori: We will have no long stop. The installation will be made in the maintenance period.
1-sector installation will be made next year, and test the function. Then we will increase
the number of sectors step by step.
Klinger: Did you make EMC3-EIRENE simulation in your divertor design?
Komori: We thank you very much for that, the code was very useful for us.
Wolf:

Can you maintain the condition of impurity hole for long time period?

Komori: During NB injection, we can maintain it almost in steady state in high-Ti phase.
Wolf:

In the impurity-hole experiments, it seems that anomalous convection of impurity also
gives effects on electron density profile. How do you think about it?

Yamada: Convection for hydrogen species is almost zero, while impurity’s outward convection isclearly high.
Tendler: I suggest the study of correlation with impurity transport and the plasma rotation.
Tendler: In your nearest plan page, what is time schedule?
Komori: NBI upgrade plan in 3 years, divertor in 4-5 years, deuterium experiment, hard to say,because of the discussion with local government. But after we get the contract with local
government, we will need 3 years to start the experiment.
Tendler: Can you say about the cost?
Komori: Total costs would be 200 M dollars for all programs listed in page 14.
Tenlder: What Q value will you get after these plans?
Komori: About 0.3, and hopefully we will extend to 1.
Van Dam: Will the beta value go up with no limit with additional heating?
Komori: Magnetic surface will be good only up to 7 %.
Van Dam: Will you control Rax by vertical field?
Komori: Yes, we will do that and maybe we will get 10 % with that capability.
Van Dam: In the mitigation of CDC event, how do you consider the effect of elongation?
Komori: Sakamoto will explain that in his talk this afternoon.
Klinger: I will ask about the fluctuation measurements, it is clear that the impurity holephenomena includes anomalous effects, do you have a plan to measure fluctuations inb-140those experiments?
Komori: Yes, we plan that. For the general discussion about the MHD fluctuations, you should wait
for Sakakibara's talk.
Sakakibara: I will explain in the afternoon.
Wolf:

In your divertor design, what is the heat flux limit ?

Komori: It is 5 MW/m^2.

Presentation by N.Nakajima: Simulation Science Project
Van Dam: I appreciate very much your nice work in experiments and simulation study. In yourfuture plan (page 19), where are you? This morning, I received information from ITER
integrated-modelling working group. The activities in NIFS simulation science division are
worth considered to form a strong part of it.
Nakajima: Yes we are strongly trying to contribute to it.
Alejaldre: I worked in theory for many years. I remember that, in old times, theory predictions gave
generally unstable results for stellarators, e.g., Mercier, ballooning instabilities. However
experiments have succeeded to break them. How do you think about the limitation oftheory work in stellarators?
Nakajima: I can give one example shown in page 3. This calculation shows unstable region. But inthe experiments, real plasmas show that such unstable region is removed in high beta
stage.
Motojima: We had the prediction of 5 % at the time of start of the LHD experiment. Equilibrium
was one of the problems, but we could solve it thanks to Prof. Todoroki. I want toacknowledge also Prof. Hayashi for his HINT-code work in high beta calculation.
Alejaldre: I am working in ITER for licensing matter. I would suggest that, on the process of yourreactor work shown in page 20, safety problems should be solved in early phase.
Motojima: Regulation issues depend on countries. I think we will make different regulations fromfission reactors.
Nishikawa: I think your hierarchical code development is very nice. Do you have near-term targets
in the simulation work for the LHD experimental results like IDB and impurity-hole
phenomena?
Nakajima: We have strong collaborations with LHD experiments and theory and data analysis
division in LHD project. We will continue such collaborations and analysis of physicalmechanism of the experimental results.
Nishikawa: I think the main objectives of LHD experiments are to understand the physics
mechanism of interesting results from LHD. For such physics understandings, small-scale
experiments like CHS, which was stopped some years ago, will be very useful. I would liketo hear the opinion of NIFS director-general.
Motojima: We have new plans to build small experiments. I will continue to encourage youngb-141

scientists for raising new proposals. Although we have a budget problem, we will continue
to work and we have several candidates in hands.
Tendler: You have made good results from LHD which have good diagnostics like electric field etc.
You should be able to make comparison studies of theories and measurements using
various numerical codes.
Nakajima: Yes we will make efforts for that type of works. However one limitation is a number ofpeople for those works. We cannot do everything. We need to make wise selections.

Presentation by M.Sato: Coordination Research
Klinger: It is impressive that you are making variety of outreaches. I would like to ask about
patents. Could you give me some numbers?
Sato:

We have different types, patents from our own researches and those with outsidecompanies. Roughly 50% of patents are produced from microwave-related studies andanother 50% from fusion-related collaborations. We have some profit but not much fromthem.

Alejaldre: I would like to give comments on tritium stuff on your page 18. We will inject an order of
100 g tritium in ITER per one discharge with the burning consumption of 0.4 g. This
amount will be much bigger in the future DEMO. The impacts of tritium problem to the
public society will be very large. We need to enhance the efforts for understanding various
aspects of tritium handling. It is very important to continue such research activities inyour group.
Wolf:

It is very important to get students/researchers into fusion research. Because you have sowide connections with various fields, please tell us what program do you have in this
aspect?

Sato:

In my opinion, we have focused only on the researches of core elements of fusion research,e.g., plasma and materials. We have to proceed to the system design of fusion reactors withsuch core materials. In this phase the most important aspect is engineering. We plan toproceed to such research phase in our coordination center.

Motojima: I would like to give general comments on the coordination center. The primary objective
is developing spin-off researches of fusion. This would be strong message from fusion to the
public. 50 years ago, in Geneva, 6000 people got together including scientists and businesspeople. Recently I gave two lectures to bankers. They are interested in fusion now.
Van Dam: On fusion science archives in page 41, why the number goes to small level (even zero?)
after 2005?
Sato:

It is just because of the time delay of the archiving work. We have, of course, materials to
be archived.

Van Dam: I ask about the organization. What is the relation between your center and the fusion
engineering research center on PWI and the tritium inventory studies? What is theb-142relation with DSS on the laser work?
Sato:

We work for rather basics objects on tritium research.

Nakajima: Prof. Sakagami belongs to DSS and he also work on laser simulation in the group in thecoordination center with experimental people for the target design.
Tendler: I heard nice results of lithium coating from TJ-II experiment in Toki conference. How doyou think about the good scientific work in small machines?
Komori: I think they made good results. We will consider such a wall conditioning technique in
future experiments in LHD.

Presentation by A.Sagara: Fusion Engineering Research
Wolf:

In your roadmap, you show various relations with your program plan and ITER
experiments. What type of research link do you expect with ITER results?

Sagara: One example would be neutron flux effects on materials.
Wolf:

Actually how will you introduce the information from ITER experiments?

Sagara: We are considering the relation with the numerical test reactor. Predictability is very
important from the model calculations.
Sudo:

We have already scientific link with ITER activities in the physics of alpha particle physics
in the simulation study.

Lee:

Here, I learned many good results from LHD experiments and simulation science. We cango ahead such researches in parallel with tokamak research for fusion reactor development.
Numerical test reactor is also useful with the activities of numerical tokamak research. By
the way, how do you think about the impact of the delay of the IFMIF project on various
fusion researches?

Sagara: I think it is ok for the database aspects, but I think that the licensing problem would be
more serious.
Lee:

We are concerned very much about licensing problem for DEMO phase.

Motojima: I think that task of the IFMIF is to find the best material, but we can use better
material.
Wolf:

14-MeV neutron source you talked, how much DPA will it produce?

Nagasaka: We expect 10^-3 dpa fluence. It is designed for basic study. For the actual material
testing, 100 dpa will be required.
Motojima: About IFMIF, could somebody give the information for the present status?
Sudo:

I think the preparation for starting design is going well, considering the present
BAactivity.

Nagasaka: I think that licensing procedure has not been fixed. JAEA is starting discussion on
licensing. For the question about the effect of delay in the IFMIF research, myunderstanding is that there are two choices. One is just to wait for IFMIF. This results indelay in the whole schedule. The other is to keep going with available irradiation data. In

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fission reactor, for example, surveillance specimens are installed on the pressure vessel.
We can start fusion reactor operation with a short-time license and surveillance specimens,
and can stop it when the specimens make some dangerous signal for embrittlement(degradation of fracture energy). The license will be expanded later, if the IFMIF data
become available.

Presentation by S.Sakakibara: High Beta and Related 3-D MHD Characteristics
Klinger: You are nicely making use of HINT results with your experiments. How do you plan toinclude the bootstrap effect?
Sakakibara: We are trying to include it with a first step by modeling it with multi-filamentcurrents.
Motojima: Do you think the effect of bootstrap current is large?
Sakakibara: Yes, I think it is large, especially for considering such as magnetic island formation inhigh beta plasmas.
Tendler: I think you are successful in taking advantage of stellarator concept with current-freetoroidal confinement proposed by Spitzer 50 years ago. This is an important milestone.
Congratulations. I suggest you to discuss further with the consideration of electric field
gradient profile at the interface of ergodic layer, as I reported in the Toki conference. This
will give you more subtle knob.
Alejaldre: What is the density profile for high beta plasmas?
Sakakibara: Typical example is shown in the presentation. Our stability calculations are with thedensity profile from the measurements.
Van Dam: It is nice to see good interplays between theory and experimental groups.

Presentation by R.Sakamoto: High Density Operation and Its Prospect for Helical Reactor
Klinger: After making long way of developing the repetitive pellet injector, it is so nice to see toachieve new regimes of helical plasmas.
Tendler: I understand it is physically important to observe the toroidal rotation for high density
plasmas. Have you tried? For the discussion of particle heat and momentum transport you
should try it even if it is difficult.
Sakamoto: Since diagnostic beam cannot penetrate, we don’t have information on that.
Wolf:

Do you have information on impurity transport? Low Zeff or do you have accumulation
problem?

Sakamoto: It is rather difficult to measure impurities in IDB plasmas, but we have some indicationsof low level of impurities in the core plasma. The simulation study has also shown the
impurity shielding by ergodic layer.

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Lee:

In page 15, you show an optimum kappa value of 1.2 for creating high density plasmas.
What is the mechanism to make kappa of 1.2 be optimum?

Sakamoto: CDC has been observed when the Shafranov-shifted axis reaches 4.1m. With theelongation, we can reduce the Shafranov shift. In the same time, extreme elongation leads
to the MHD activity. Thus, elongation must be smaller that kappa of 1.2 because of thestability aspect.
Lee:

What kind of MHD ?

Yamada: Too much elongation raises, usually, the interchange mode.
Lee:Do you have a modelling for the stability?

Yamada: Yes, we have Mercier calculation. But this is sufficient condition and not the necessary
condition. Liner stability analysis suggests that substantial growth rate is expected for D_I
in Mercier calculation of 0.2 or 025.
Motojima: Could you tell your feeling for the difference between high density plasmas and high beta
plasmas (with low B field)?
Sakakibara: For IDB plasmas, the interchange mode in the core is stable due to the magnetic well,although it is not (in linear calculations) for high beta plasmas. In IDB case, the plasma
periphery is unstable (in linear calculations) but MHD fluctuations are in small levelcompared to standard high-beta case.
Motojima: Present pellet velocity is about 1 km/s. Is it possible to increase it to 10 km/s for getting
better penetration?
Tendler: How do you plan to extend it for the use in DEMO?
Sakamoto: The improvement of penetration given by the velocity increase depends with the scalingof (velocity)^0.3 power. So it is not beneficial to increase the velocity.
Motojima: How about 100 km/s?
Sakamoto: It will be technically difficult because the hydrogen ice pellet is not tough enough forsuch a high speed. Pellet penetration can be improved utilizing the drift movement ofplasmoid in the plasma.

Presentation by T.H.Watanabe: Turbulent Transport and Zonal Flows
Klinger: It is a beautiful result. In inward shifted case you found larger zonal flow amplitude. With
the E field effect on zonal flow, you also made good results. Can you combine two effects
consistently?
Watanabe: Yes, we will proceed to include multiple-helicity model. I expect the inward-shifted
configuration, the effect of E field on zonal flow creation would be stronger.
Klinger: It is nice for stellarator community to know that the non-ambipolar E field makes
turbulent suppression.
Tendler: Including E field effects on the zonal flow, can you make the self-consistant modeling?
Watanabe: We will try to do it by involving the feedback from both physics elements.

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Tendler: How do you include E shear effect, which provides turbulent suppression?
Watanabe: In our simulation work, effect of E field on zonal flow is stronger than the stabilization
effect of the E field shear. We will proceed to include the E field shear for the next phase of
our work, but we are going first to concentrate on the analysis of E filed effect on zonal flow
Lee:Your work on ETG is in the early stage based on the slab model. This is very expensive
study and nice results. Do you think that your ETG work is applicable for toroidal
geometry?

Watanabe: Toroidal damping of ETG is important. We will try but not very soon.
Alejaldre: For the better understanding of LHD results, calculations for outward-shifted case arealso important. I also suggest you try to calculate TJ-II case because we have measurementof E field profile.
Klinger: Do you need higher computing power for making further step?
Watanabe: I think we have been able to calculate ITG mode with the existing computers. For
making further study, like ETG in toroidal geometry, I think we need more power.
Van Dam: It is really very strong work. Year ago, I recall that you didn't have consistent simulation
results with LHD experiments. Now the drift motion is included and you made a success.
How about making a next step for making a proposal to the experiment to check simulation
results?
Watanabe: Our present concern is the turbulent evaluation with Er. We would like to make a
prediction for LHD deuterium experiment where the isotope effects make the E field
different from the hydrogen experiment.
Nakajima: We need global simulation to include the E field shear effects. We will go step by step.
Watanabe-san is now making ITG and ETG simulations separately. For hierarchy
simulation, we will calculate both simultaneously, but again we will go ahead step by step.
Tendler: In EU, we have a new supercomputer. You can be the big user of that.
Lee:

Electron anomalous transport is another big problem. We hope you can give a good insightfor that. Also the impact of turbulence on particle transport must be the important issue
for the next target in your work.

Presentation by T.Nagasaka: Development of Long-life Liquid Blanket
Klinger: You are making deep studies of blanket in collaborations with university people andcompanies. Could you tell your present situation?
Nagasaka: Yes, we have much collaboration with universities and companies. Our business is theintegration of fundamental research and elemental technology. Generally university people
are not organized in a project. They want to do what they want to do. We need management
for research subjects, planning and framework. We are satisfied with the collaboration
studies, but we need more. Recently we have reached the step of fluid convection study. It
needs larger budget and more number of people. I think we need to grow the community up

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now.
Klinger: For your engineering collaborations, with who are you collaborating, nuclear engineering
people or what university groups?
Nagasaka: We have common research issues with fission reactor and other material people. Ferritic
steels including molybdenum were developed in fission reactor material research. In fusionmaterial, molybdenum was replaced by tungsten from the aspect of low activation. It was
found that the ferritic steel containing tungsten showed larger creep strength than the
molybdenum steel. So, people started to consider the tungsten steel as fission reactor
materials, turbine materials and etc. This is a good example of our communication to otherresearch fields.
Alejaldre: For the simulation study of the interaction of neutrons with materials, do you have thecollaborations with theory people?
Nagasaka: We have to extrapolate the present fission reactor data to high dpa case. In order toclarify the mechanism, we have activity of computer simulation. We have numerical workfor the fundamental processes in multi-scale modeling activity.
Lee:

ITER would be the last chance for testing liquid blanket. How do you select the final
candidate of blanket among many candidates? For liquid blanket, how will you test it in
the ITER experiment?

Nagasaka: In ITER, the TBM was limited by the technologies available at this moment. JAEA
people expect 3 campaigns in ITER-TBM experiments. The 1st TBM starts at ITER Day 1st,and ends at the end of D-D experiment. 2nd one is the same TBM as the 1st one, and starts
with D-T experiment and will be operated for several years. The 3rd one will be different
from them, and is recognized as advanced type. I expect that we can test our liquid breeder
TBM in the 3rd campaign. It will be around 2020.
Lee:

Replacing TBM itself would be possible, but there is no possibility of changing the blanket
concept because it would be difficult to change the whole heat cycle system for the blanket.

Motojima: ITER design has been made with the primary target of testing fusion reactor concept.
The limitation of budget made such a decision. In this context, I recall the same problem
for material selections: whether we should select stainless steel or the low activationmaterial.
Sagara: We have been discussing so many years about the blanket design. We do not have enoughdatabases to make a correct final decision.
Lee:

I am responsible for TBM type selection. I have to say that putting just a TBM in ITER is
possible but sufficient physical testing of that is not possible.

Alejaldre: I think that the solid TBM has passed licensing procedures. For liquid type design, an
additional licensing process would be needed.
Motojima: Neutron flux is not sufficient for blanket test in ITER. It is better to open the possibilityof selecting various types of blankets for university people.

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Final session for the review
Tendler: I was deeply impressed with the results achieved in NIFS. Fantastic achievement of new
regime in stellarator research has been made. These good results were made strategically,i.e., well arranged combination of theory and experimental works. I would like to suggest
an important subject you can proceed, which is the momentum transport discussion.
Wolf:

Concerning your future upgrade plan, it might be very good subject to have the steadystate divertor operation. You have made great achievements of high beta plasma
production and high density plasma operations with. It would be nice if you could discuss
integrated approach to reactor-relevant regime. Creating the ITB is good result and I
would like to hear the discussions for its physical mechanism. I am envious to know yourstatus of good collaboration with scientists in fields of the nuclear engineering andtechnology.

Sudo: Thank you very much. I think, in Karlsruhe, for example, you also have good collaboration
works with engineering and technology, where I visited two days ago for the BA meeting.
Klinger: I am honored to join this review meeting. LHD is no doubt a leading stellarator in theworld. I think you should continue your direction. Pellet injection development, which has
been continued many years, have now led to a new regime of stellarator plasmas. Beta
limit study marked a good achievement. Systematic progress in heating power has beenmade. I observed also growing technology developments in universities and companies,
whose products are nicely involved in LHD experiments. Understanding IDB and CDC
may need further collaborations of theory and experiments. Closed divertor is in the stepby step progress. I see strong activities although I am not a specialist for this field. NIFS iscertainly a center of collaboration with 140 universities and institutes. Today young
scientists made nice presentations for remarkable results.
Takuma: Thank you very much for preparing nice presentations. They were all well prepared. I see
young excellent scientists have grown up. What we hoped for LHD in the discussions at thestarting stage has been now established by NIFS people. We hope LHD experiments goahead further.
Itoh:

During last six years, by the direction of Motojima sensei the many great results came out
from LHD and also high grade works were output from the other groups. I would like tosay congratulation to Motojima sensei and all of the staff of NIFS.

Nishikawa: When I looked the program of this meeting, I thought the morning session would beunderstandable because the talks would be for general topics. However I felt that the talks
in the afternoon would be too difficult for me because the topics would be on details in the
research. I was afraid that I could not follow them. Now I found the case was opposite.
Talks in the afternoon from young scientists were very nice. I thought about making nasty
comments but I realize that I can give only awarding comments. I was a chairman ofreview committee for the discussions to decide the start of the LHD project. We made lotsof discussions about feasibility of superconductors, steady state operations, physicalb-148

problems, high Ti achievement, high beta, high Te with electron root. Now it seems that allitems were completely accomplished.
Alejaldre: I am very much impressed by the presentations. In the last two years, I was away fromstellarator research and did not follow it closely. I have been engaged in the licensing workof the ITER, which gave me good experiences. Disruptions, instabilities, runaway electronsin ITER are big issue. I realize the potentiality of LHD is great. So I will introduce such
nice achievements to tokamak community to convince them. Comparison study of two
concepts would give good understanding of physics. Finally I suggest you, say, for the nexttime, to present a long-range plan of the institute, which is not only for 5 years but longer
plan, about how you can contribute to ITER. It would be a difficult job for the next
director-general.
Lee:

I am very much honored to come to Takayama for this review committee. I give comments
and recommendations I prepared by the request from Sudo sensei. Significant maturing of
LHD experiment is very good. Machine itself is in a high level of heating and diagnostics.
Simulation studies have been grown up and they are one of main part in NIFS, which isalmost equal level to LHD experiment. Two departments were nicely organized. Positive
feedback is very nice between simulation and experiment. I encourage this way strongly. I
observe much improvement from the time of my first engagement. I notice that turbulence
study in momentum andparticle transport is important. I realized a growing integrity infusion engineering field. It is impressive to know outward spin-off in the fusion engineeringand reactor study. We should be careful for liquid blanket research. It needs to be looked
carefully with timeline, and consider how to test it if it were not applied to ITER. I would
like to listen to your insights on this topic. In conclusion, I congratulate to Motojima san forhis 6-years great work from the construction to realization of scientific activities in theinstitute. Our fusion research is a sort of marathon or relayed running. To keep momentum
is important and leadership with future vision is important. We should go together withmultiple generations.

Van Dam: I repeat the sayings all reviewers made already. I appreciate your good hospitality.
Similar to Prof. Lee, I have been for 5 years in this review committee. At 5 years ago, theresults were nice but they keep getting better. I learned nice results in gyrokinetics,
multi-scale and hierarchy simulation, micro turbulence, energetic particles, macroscopic
MHD, laser plasma simulations, and reconnection studies, etc. In JIFT program we have
had productive collaborations. I like such an informal style of the review meeting this year,
full day meeting is much better than sequence of half day meetings. PR, outreach including
kids science museum are highly recognized. Very interesting LHD experimental results
will be studied by theory and simulation people in NIFS. Talks in the afternoon were very
good. I expect NIFS could have much more number of good talks in the same level. I
confirmed the publication records are increasing. NIFS’ presence at the last IAEA-FEC
meeting were very impressive. Motojima sensei has been an excellent leader. I have beenb-149

observing him for the education of myself.
Nishikawa: LHD program was discussed at the initiation phase, based on pure scientific arguments.
I encourage young scientists to do the same thing: discuss among yourself, discuss from thepure scientific point of view, w/o concerns on budget, politics, discuss the future plan.
Tendler: Now stellarator has become from “Plan B” to “Plan A” under the Prof. Motojima’s strong
leadership. Congratulations.

Closing address
Motojima: Thank you very much. I have been very much excited here. I express again thanks for all
coming to Takayama. Your comments encourage us and stimulate our research. It is 20
years after the NIFS was founded. It is short in some sense and very long. I feel time flies.
20 years is enough to establish LHD experiment and simulation, to make the scientificframework. It is fun to see young people grow up and improve their capability. Within 3months I will complete my work as a director-general for 6 years. I want scientists in NIFS
to keep the momentum to realize fusion (in my calculation it will be 27 years and 1 month).
I might be at the position of review committee member from outside of the institute.
Finally I would like to give my sincere thanks to my wife. Without her support I could nothave survived.

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Inter-University Research Institute Corporation
National Institutes of Natural Sciences

National Institute for Fusion Science322-6 Oroshi-cho, Toki, Gifu, 509-5292, Japan

http://www.nifs.ac.jp/