J. Plasma
J.
Plasma Fusion
Fusion Res.
Res. SERIES,SERIES,Vol.
Vol.6 6(2004)(2004)100–106
000–000

The Legacy of Masahiro Wakatani
VAN DAM James W. and HORTON C. Wendell, Jr.
Institute for Fusion Studies, The University of Texas, Austin, Texas 78712, USA(Received: 18 February 2004 / Accepted: 7 April 2004)

Abstract
As a memorial to Masahiro Wakatani, late professor of plasma physics at Kyoto University, a review is given of
his legacy of achievements in scientific research, international collaborations, university administration, student
guidance, and personal life.
Keywords:
Hasegawa-Wakatani equation, turbulent transport, helical system stability, drift wave, reduced MHD equation

1. Introduction

Division (1976-1978).
In 1978 he joined the Plasma Physics Laboratory at
Kyoto University as an Associate Professor. He was promoted
to full Professor in 1985. In 1996 he became a Professor in
the Department of Fundamental Energy Science and theDepartment of Nuclear Engineering.
He was elected a Fellow of the American PhysicalSociety in 1990.
He died on 9 January 2003. Two obituaries about him
have been published [2,3].

The international community of fusion plasma physicists
was deeply saddened by the unexpected loss of one of its
most respected members, Prof. Masahiro Wakatani, of Kyoto
University, who died from a cerebral hemorrhage on 9
January 2003. This paper, based on a talk [1] presented during
a special memorial session at the 13th International Toki
Conference (9-12 December 2003), is offered as a tribute in
his memory.
Professor Wakatani had a brilliant career as a scientificresearcher, international collaborator, university leader, andteacher. In this paper, after providing a brief biographicalsketch, we will describe each of these aspects of his verysignificant legacy and also offer some personal comments
about him.

3. Legacy of innovative researchWithout question Wakatani was one of the very best
theoretical and computational plasma physicists in the world.
He published many influential papers. His creative andoriginal work on nonlinear MHD, drift wave instabilities,
stellarator confinement, and ion-temperature-gradient mode
dynamics is famous. Here we provide a brief description ofhis major contributions to several areas of theoretical plasma
physics research.
According to Prof. Tokuhiro Obiki’s obituary [2],Wakatani’s scientific talent and brilliance were alreadyobvious in his student days. He had the highest marks of any
student ever in nuclear engineering. For his Ph.D. thesis, hecarried out the first application of neoclassical theory to thetoroidal pinch confinement device. He used the neoclassicaltheory of Roald Sagdeev and Alec Galeev, which was brandnew at that time, to calculate the collisional diffusion
coefficients in a toroidal pinch [4].
After graduation, he continued his work on stability andtransport, switching his attention first to the tokamak device,
which had much better confinement than the toroidal pinch,and (when he joined the faculty at Kyoto University) also to

2. Capsule biography
Here we briefly list some selected biographical details
and important dates in his career. This list will serve as achronological framework for the description of his many
accomplishments.
He was born on 15 May 1945, in Osaka, Japan.
He attended Kyoto University for his undergraduate andgraduate education. He graduated with a B.Sc. degree (1968)
and a Master’s degree (1970) in nuclear engineering. He thenobtained a Dr.Eng. degree in electrical engineering (1973)
with a thesis entitled “Magnetohydrodynamic Equilibrium andStability of Toroidal Pinches” under the guidance of his thesis
advisor, Prof. Ryohei Itatani.
After graduation, he was first employed at the Japan
Atomic Energy Research Institute as a Research Associate in
the Division of Thermonuclear Research (1973-1976).
Subsequently he went to the Institute of Plasma Physics,
Nagoya University, as a Research Associate in the Theory©2004 by The Japan Society of Plasma
Science and Nuclear Fusion Research

Corresponding author’s e-mail: vandam@physics.utexas.edu
1100Van Dam J.W. et al., The Legacy of Masahiro Wakatani

helical confinement devices, especially the Heliotron/torsatronline. A major scientific accomplishment, published in the yearthat he moved back to Kyoto, was his derivation of reduced
MHD equations for helical systems [5]. These equations were
derived by means of an averaging approach, based on the“stellarator expansion technique.” They are a simplified
version of the full MHD equations, but yet retain the essential
helical physics and – quite importantly – are amenable tononlinear numerical simulations. These reduced equations arestill today the popular standard model, used worldwide for
MHD analysis and machine design.
Perusal of his extensive list of publications leads to an
appreciation of how much work he did on analyzing Heliotron
experimental results. He was a co-author on many papers
dealing with pellet injection, heating, equilibrium, stability,transport and confinement, etc., in Heliotron experiments [6].
Furthermore, he, with his students, carried out studies of a
Helias-Heliac hybrid stellarator [7] and helped with the designof the Heliotron-J device, which was subsequently constructed
and is now operating at Kyoto University. Heliotron-J is ahelical axis device, based on the quasi-isodynamic (i.e., quasiomnigenous) optimization approach to the helical-axis
Heliotron line.
In the early 1980’s, shortly after the launch of the U.S.Japan fusion theory exchange activities (to be described inSec. 4), Wakatani began to study anomalous transport due toturbulence arising from micro-instabilities, a major obstacle
to improved plasma confinement. In 1983, working with Dr.
Akira Hasegawa (then at Bell Lab), he derived a set of
nonlinear evolution equations that describe strong turbulencecaused by resistive drift-wave instability at the edge of aplasma [8]. Using these equations, they showed the existenceof an inverse cascade of energy from short to longwavelengths in plasma turbulence. They also found a
prototype mechanism for generating large-scale poloidal flow
structures (e.g., zonal flows and streamers in tokamaks).
These “Hasegawa-Wakatani equations” for nonlinear
drift waves have become extremely well known and hence
deserve special notice in any description of Wakatani’s
accomplishments. We speculate that perhaps because he lived
in the ancient cultural region of Kyoto and Nara, he liked
theories that were simple, orderly, and yet elegant, like a Zen
garden. Thus, the Hasegawa-Wakatani theory created a highly
simplified formulation of the drift wave equations, in which
two coupled nonlinear partial differential equations provide a
powerful paradigm for studying the transition from collisional
drift wave turbulence to collisionless drift waves, all in termsof a single parameter. These equations immediately becamevery popular and have been extensively used by many otherresearchers. One example is the use of the HasegawaWakatani equations by theorists and applied mathematicians
to test closure models for describing turbulence.
Wakatani went on to write nine more papers with
Hasegawa, two of which were also published in PhysicalReview Letters. The results of one of these papers [9], a studyof the self-organization of electrostatic turbulence, have beenused in some recent experimental work [10] to explain shear
flow-induced transport barriers.
Wakatani was clearly a world leader in the studies ofdrift wave and resistive-g mode turbulence. He was unique inthat he not only developed a simple paradigm model (namely,
the two-dimensional Hasegawa-Wakatani equations with one
parameter), but also constructed technically complete models
for three-dimensional helical systems. He gained aninternational reputation for his work on drift wave instabilities
in toroidally confined plasmas. His studies of anomaloustransport induced by ion temperature gradient (ITG) andelectron temperature gradient (ETG) instabilities are wellknown. One of us had the privilege of co-authoring a seriesof ITG and ETG papers with Wakatani and also several of
his students (especially Dr. Hideo Sugama) [11].
Wakatani and his students skillfully used large-scalecomputing for attacking complex systems. A rather recent
example was his work on simulating the dangerous plasmatransport due to electron-temperature-gradient turbulence inreversed-shear, nearly collisionless toroidal systems with arecord number of representative electrons per cell in a selfconsistent field [12].
In addition to doing original research, he somehow foundtime to publish five books. He co-authored two textbooks with
Prof. Kyoji Nishikawa. The first, Physics of Continuous
Fluids [13], unfortunately available only in Japanese, covers
material from low-temperature quantum fluids to hightemperature plasmas. Their other jointly written book, Plasma
Physics: Basic Theory with Fusion Applications [14], wasused by us as a graduate-level text at the University of Texasand has been reprinted in three editions so far. Two of
Wakatani’s other books were related to U.S.-Japan exchange
activities. One was a conference proceedings, U.S.-Japan
Workshop on Ion Temperature Gradient-Driven Turbulent
Transport, Austin, TX, 1993 [15]. Another arose out a seriesof U.S.-Japan workshops, which he helped to organize, andscientific exchange visits, in which he participated (mostly
with scientists at New York University), concerning thedevelopment of the BETA equilibrium, stability, and transport
codes and their application for stellarator design [16].
Unquestionably his magnum opus was his final book,
Stellarator and Heliotron Devices [17]. This text is extremely
well written, providing both physical pictures as well as
detailed descriptions, and covering not only MHD andresistive MHD physics but also drift wave physics (veryimportant for helical plasmas) – in short, a veritable “bible”
of stellarator theory.
An impressive feature of Wakatani’s research is that it
combined deep physics insight and development offundamental new theory, with applications to urgent, real-life
problems. We think that the reason for this dual style was his
motivation to achieve the ultimate goal of abundant, clean
fusion energy for the benefit of world society. He sought towork toward this goal by the three means of predictive
capability for simulations and theory, the ability to design andcontrol plasma parameters and profiles, and critical2
101

Van Dam J.W. et al., The Legacy of Masahiro Wakatani

experimentation.

at the newly created Institute for Fusion Studies at the
University of Texas (Fig. 3). Table 1 lists all of the JIFT
workshops for which Wakatani served as organizer. Rather
impressively, in 1989 he co-organized four workshops, twoat Kyoto University and two in the United States. In total, heorganized 14 such workshops. One of these, to have been heldin 1991, was, unfortunately, called off at the last moment; theJIFT Annual Report for that year quaintly noted that it had
been cancelled “in view of the changing priorities in the U.S.
fusion program.” Besides the workshops that he organized,
Wakatani also participated in many others, on a wide rangeof scientific topics (see, for example, Fig. 4).
We offer two further comments concerning Wakatani’svaluable participation in the JIFT workshops. During the first
decade of JIFT activities, Wakatani, in collaboration with Dr.

4. Legacy of international collaborations
Wakatani was an absolute pillar of support for U.S.Japan collaboration activities. In particular, for 22 years heprovided valuable service to the Joint Institute for Fusion
Theory (JIFT), a bilateral program established in 1980, which
coordinates fusion theory exchange activities between Japanand the United States.
A small anecdote illustrates one of the ways in which
Wakatani played a key role in establishing the U.S.-Japan
collaboration program in controlled thermonuclear fusionenergy research. In 1980 a delegation of U.S. scientists
accompanied by a Department of Energy representative (seeFig. 1) undertook a tour of major Japanese fusion facilities inorder to explain the opportunities of the proposed new U.S.Japan exchange program and build support for its approval.
The first important visit on their tour was to the Heliotron
Laboratory directed by Prof. K. Uo at Kyoto University. Herethey were saved from failure by Wakatani’s quick thinking.
Professor Uo was then at the height of his career as theacknowledged “shogun” of stellarator/torsatron research inJapan. His Kyoto University laboratory was famous for
successful Heliotron experiments that produced high-quality
plasma confinement rivaling that of tokamaks, but without
large internal currents. After the U.S. visitors had presented
their vision for the proposed exchange program, it was clearthat Prof. Uo was ready to say “No” (in the indirect Japanesemanner). However, just before he uttered any irrevocablewords, Prof. Wakatani understood what the true problem wasand quickly said, “Uo-sensei, the exchanges would be with
U.S. theorists and modelers, and I will keep them upstairs in
my department.” After a long silence Prof. Uo managed apleasant face and said that such an exchange program could
be started in the Heliotron Laboratory – but with theunderstanding that the visitors were to stay out of theexperimental areas. One could say that due to Wakatani’s
perceptiveness, it became possible for the very successful
JIFT exchange program to be launched. Soon thereafter, Prof.
Russell Kulsrud from Princeton University spent a sabbaticalat Kyoto University, working on electron thermal transport inhelical systems. Subsequently a number of other U.S.
scientists followed in his path to work in Kyoto with Wakataniand his theory group.
Wakatani served as a vital member of the JIFT Steering
Committee for 13 years (Fig. 2) and, before that, a memberof the Japanese Management Committee for JIFT for nine
years). For two years (1998 and 1999), he also stepped in as
the interim JIFT executive secretary on the Japanese side.
Besides his administrative role in JIFT, Wakatani wasextremely active as an organizer of and participant innumerous workshops, both in Japan and in the U.S. Both of
us worked closely and productively with him over the years
in the arranging of JIFT activities and the organizing ofworkshops. In fact, Wakatani headed the delegation ofJapanese scientists to the first JIFT workshop, held in 1980
3
102

Fig. 1

Visiting U.S. delegation to promote JIFT in 1980, withJapanese hosts, in front of the Institute for Plasma
Physics, Nagoya University. Front row (left to right):
T. Kamimura, Y. Terashima, D. Baldwin, S. Hayakawa,
D. Nelson, H. Kakihana, J. Dawson, T. Taniuti, W.
Horton, M. Tanaka; back row (left to right): Y. Ohsawa,
T. Hatori, Y.H. Ichikawa, I. Kawakami, K. Nishikawa,N. Yajima, T. Sato, M. Wakatani.

Fig. 2

Participants at the 1990 meeting of the JIFT Steering
Committee (from the left): Y. Nishida, S. Stewart, M.
Kono, M. Wakatani, W. Sadowski, J. Van Dam, T.
Kamimura, D. Baldwin, W. Horton, and J. Dawson.

Van Dam J.W. et al., The Legacy of Masahiro WakataniFig. 4
Fig. 3

Participants in the 1980 JIFT Workshop on Theory of
Non-Axisymmetric Confinement Systems (University ofTexas at Austin, 8-12 December). Front row (left toright): T. Watanabe, A. Fukuyama, J. Todoroki, M.
Wakatani, D. Ross, T. Kamimura, H. Sanuki, W. Horton.
Second row: R. Hazeltine, K. Shaing, M. Schmidt, A.
Boozer, D. Spong, E. Maschke, C. Chu. Third row: J.
Van Dam, R. Cohen, H. Berk, T. Cayton, G. Miller, A.
Bayliss, D. Pearlstein, S. Yoshikawa, H. Strauss,
T. Kaiser.

Official photograph of participants at the 1986 JIFTWorkshop on Statistical Plasma Physics. Wakatani issecond from the right in the back row.

Table 1 List of U.S.-Japan Joint Institute for Fusion Theory workshops organized by Wakatani (title ofworkshop, names of co-organizers, date, and location).

4103

Van Dam J.W. et al., The Legacy of Masahiro Wakatani

Ben Carreras of Oak Ridge National Laboratory and others,
went on to lead a series of U.S.-Japan workshops on MHD
equilibrium and stability. At one point the JIFT Steering
Committee requested a report that would summarize the broad
range of research issues concerning macroscopic equilibrium
and linear and nonlinear stability properties of magneticallyconfined plasmas in a variety of configurations. A small,
invitation-only JIFT Workshop on 3D MHD Simulation,
including 11 Japanese scientists (with Wakatani as one of theimportant participants), was held in March of 1986 for thispurpose. The resulting report [18] described the major
computational achievements to date and then laid out future
directions for continued work. Our second comment is that
Wakatani was very instrumental in leading a benchmarking
study of helical system simulation codes. This constituted along-standing JIFT effort – carried out collaboratively by
Japanese, Russian, European, and U.S. scientists – to compare
stability predictions from various different MHD numericalcodes that had been applied to a common stellarator
equilibrium configuration. Eventually this effort resulted in a
major joint publication [19].
Finally, we note that in 1988 Wakatani had the honor ofbeing chosen as the JIFT Visiting Professor to the U.S. He
split his time between Oak Ridge National Laboratory andthe University of Texas.
In addition to his extensive involvement in U.S.-Japan
exchange activities, Wakatani was also an vigorous
contributor to other international fusion collaborations. He
played a leading role in the worldwide program to design theInternational Thermonuclear Experimental Reactor (ITER)
device. In particular, he was the chair of the international
Physics Expert Group on Confinement and Transport for
ITER. As such, he contributed as one of the editors of the
500-page “ITER Physics Basis” document [20], published asa special issue of Nuclear Fusion. Subsequently and until his
untimely death, he served as a member of the Topical Groupon Transport and Internal Transport Barrier Physics, one ofseveral such groups for the International Tokamak Physics
Assessment (ITPA) effort.

Culture, Sports, Science, and Technology, this center was
funded for five years (2002-2006). Among our lastcorrespondence with Prof. Wakatani were emails from him
announcing this award and arranging exchange visits with the
new center. He lived only three months longer. In a sense,
this Center of Excellence is a capstone to his career.

6. Legacy of student guidance
As a professor at Kyoto University, Wakatani attracted
and trained many outstanding students. Over the years we had
the privilege of meeting many of his successive students. We
watched them carry out their thesis research under his careful
oversight and develop into mature and productive scientificleaders in their own right. Typically, a paper written by a
Wakatani student was characterized by being well written,
involving smart physics, focusing on a hot topic, and applying
both skillful theoretical analysis and numerical simulations.
Moreover, Wakatani was very willing to share credit with his
junior colleagues. He usually put forward the student as thefirst author on a joint paper.
To his students he was always “Wakatani-sensei.” Yet hehad a human touch with them. In the autumn he and his
students always went on a hiking expedition; at New Year’s
they would have a party together; whenever a student
graduated, they held a send-off party [21]. Wakatani was thefirst to advocate an advanced graduate student as a participant
in the JIFT exchange program; previously all the exchange
scientists had been those already established in their careers.
He also continued to keep an encouraging eye on his former
students’ progress after graduation.
The uniformly high quality of the students he produced
is indeed impressive. In a review [22] written by Dr. John
Johnson, a frequent collaborator of his, concerning Wakatani’slast book, he made this comment: “I have always respected
the author for the quality of students he produces... Thesestudents are a good demonstration of the usefulness of thisbook.” Indeed, the Masters and Doctors theses of students
who graduated under his tutelage comprised source materials
for this excellent textbook.
We ourselves observed that in the 1990’s, theory groups
in Japan would even put in pre-requests to Wakatani for him
to produce students who would have certain specific skill sets
and for whom jobs would be already waiting.
Graduates of the “Wakatani school” now populate thevarious plasma theory groups in Japan. A list of the 17
graduate students whose Ph.D. thesis research he supervised
is given in Table 2. By carrying on his methods and ideas,
they constitute another vital part of his enduring legacy.

5. Legacy of university leadership
Wakatani strongly contributed in terms of administrative
leadership at Kyoto University, one of the premier institutionsof higher education in Japan and worldwide. Here we mention
two such areas.
He was a key member of the Kyoto University Council.
As such, he assisted with a major re-organization within
Kyoto University, which occurred in 1996. Also, he provided
valuable direction in preparing for the re-organization of theentire national university system in Japan, to become effectivein April 2004.
Second, he became Vice-Dean of the Graduate Schoolof Energy Science at Kyoto University in April 2002. In thiscapacity he led a successive effort to establish a 21st Century
Center of Excellence in Energy Science. In a national
competition sponsored by the Japanese Ministry of Education,

7. Legacy of family
It was very clear to us that Prof. Wakatani was a familyman, proud of his charming wife (Yasuko, a piano teacher)and their three musically talented daughters (Seiko, Ayako,
and Yohko). He especially enjoyed listening to his wife anddaughters perform classical chamber music for piano andviolin. Upon occasion he brought his family along with him
5104Van Dam J.W. et al., The Legacy of Masahiro Wakatani
Table 2 List of Ph.D. students supervised by Wakatani.

of Prof. Wakatani’s talks, during which many of the scientists
in the audience initially missed his key discovery of the onsetof sheared flows in a collisional drift wave simulation, aphenomenon that is now invoked as the basis for transportbarriers in many toroidal plasmas. In this respect perhaps it
would have been helpful for Wakatani to be more emphaticor dramatic – but of course that would have been inconsistent
with his reserved nature.
To work with Wakatani was both a privilege and apleasure. It was, however, also a responsibility, because heexpected much from his collaborators. He always attracted
the brightest co-authors.
His personal integrity, in addition to his scientificcreativity and leadership, were highly respected by theinternational scientific community. An indication of theinternational esteem in which he was held is the fact that hewas selected to give the theory summary talk at the 1988
IAEA Fusion Energy Conference [23]. Wakatani was widely
known to be modest, deep thinking, and reliable, with
impeccable ethical standards. Interestingly, in his stellarator
textbook, in the chapter that describes the reduced MHD
equations for helical systems, he does not cite his own
pioneering work, but instead, with characteristic modesty,
gives a reference to the paper by Strauss [24] that generalized
these equations to finite plasma pressure.
One of his former students told us that Wakatani-sensei
had in his office a picture of Buddha with a peaceful face,
and that Wakatani never got angry with his students, but wasalways very patient. Once, when a student was scolded by
the laboratory director because the computer room was messy,
Wakatani himself pitched in and helped the student clean itup.
Reviewing the list of papers he published, the books hewrote, the students he guided, and the international activities
he was involved in, one realizes how incredibly diligent hewas. Prof. Obiki in his obituary noted that at home, Wakatani
often worked into the night after his family had gone to bed.
Obiki also commented that instead of simply relying on his
natural talents, Wakatani went on to make achievements thatwere obviously undergirded by layers upon layers of hardwork.
His excessive obligations may have contributed to his
early death. Very likely there were other important projects
that he wanted to tackle. It certainly had been expected that
he would continue to make great contributions toward
Japanese and world progress in fusion energy.

on visits to the U.S.
Dr. John Johnson of the Princeton Plasma Physics
Laboratory and his wife, Barbara, told us that Wakatani once
wanted his middle daughter to have an opportunity to practiceher English. Consequently, when he went to Princeton for aweeklong workshop, he took her along. While he stayed at a
hotel and attended the meeting, his daughter stayed with theJohnsons at their home. She was quite a help to them because
at the time Mrs. Johnson had broken her arm. Dr. Johnson
recalled that once when he tried to help wash dishes, thedaughter shooed him out of the kitchen, saying, “A Japanesehusband wouldn’t do that!”
Wakatani understood that scientific progress often occurs
through discussions carried out away from the pressure-filledatmosphere of conferences and workshops. He and his
students often took visitors to see famous temples and otherhistorical sights in Kyoto and Nara, while informallycontinuing to talk about scientific issues. In this way, making
progress on a research problem with Wakatani was awonderful experience.
He and his wife also extended many personal invitations
to visit their home in Nara. In this respect, too, both of us are
fondly grateful for their kind hospitality. Fortunately we hadsome opportunities to host Prof. Wakatani and his family here
at Texas. He particularly enjoyed visiting the Alamo, a shrine
to the battle for Texas independence in 1836 (which date hethought was comparatively recent, relative to Japanese
history).

8. Legacy of personal characterIn our opinion, a significant part of Wakatani’s greatness
was his outstanding personal character. As a scientist,
collaborator, administrator, teacher, friend, and human being,
he was a complete gentleman – courteous, dignified, calm,
gracious, and considerate of others. He looked for praiseworthy characteristics in other people; he disliked being
critical of others. When leading discussions he always gave
all participants an opportunity to express their individual
views. Even to those who opposed him, he was willing tolisten, be fair, and provide helpful information.
His own presentations were thoughtful and reasoned,
convincing his hearers on the basis of logical arguments andexperimental evidence. He well understood that actions speak
louder than words. We ourselves learned to listen carefully toevery word he said, because he would proceed logicallythrough his material – only once. One of us (WH) recalls one
6105Van Dam J.W. et al., The Legacy of Masahiro Wakatani

9. Conclusion

Physics 5, 14.1 (2003) (http://www.njp.org/).
[12] Y. Idomura, M. Wakatani and S. Tokuda, Phys. Plasmas
7, 2456 (2000); Y. Idomura, S. Tokuda, Y. Kishimoto and
M. Wakatani, Nucl. Fusion 41, 437 (2001).
[13] K. Nishikawa, K. Ohbayashi and M. Wakatani, Physics
of Continuous Fluids (Asakura Shoten, Tokyo, 1981, inJapanese).
[14] K. Nishikawa and M. Wakatani, Plasma Physics: Basic
Theory with Fusion Applications (Springer-Verlag,
Berlin, first edition 1990, second edition 1993, thirdrevised edition 2000).
[15] F. Bauer, O. Betancourt, R. Garabedian and M. Wakatani,
The Beta Equilibrium, Stability, and Transport Codes:
Applications to the Design of Stellarators (Academic
Press, San Diego, 1987).
[16] W. Horton, A. Wootton and M. Wakatani, editors, U.S.Japan Workshop on Ion Temperature Gradient-Driven
Turbulent Transport, Austin, TX 1993 (AIP Press, New
York, 1994).
[17] Masahiro Wakatani, Stellarator and Heliotron Devices(Oxford University Press, New York/Oxford, 1998).
[18] B. Carreras and T. Sato, U.S.-Japan 3D MHD
Workshops: Report on the Activities of the Last Five
Years (1986).
[19] Y. Nakamura et al., J. Comp. Physics 128, 43 (1996).
[20] ITER Physics Basis Editors, ITER Physics Expert Group
Chairs and Co-Chairs, and ITER Joint Central Team andPhysics Integration Unit, Nucl. Fusion 39, 2137 (1999).
[21] Photographs taken by students at these various social
events are posted on the fusion science and plasma
processing group web page at http://www.center.iae.
kyoto-u.ac.jp/wakak/index.html.
[22] J. Johnson, “Review of Stellarator and Helical Devices
by M. Wakatani,” Nucl. Fusion 39, 293 (1999).
[23] M. Wakatani, “Summary on magnetic confinement
theory,” in Plasma Physics and Controlled Nuclear
Fusion Research 1988, Twelfth Conference Proceedings,
Nice, 12-19 October 1988 (International Atomic Energy
Agency, Vienna, 1980), vol. 3, pp. 605.
[24] H.R. Strauss, “Stellarator equations of motion,” Plasma
Phys. 22, 733 (1980).

Summed up, the achievements of Prof. Masahiro
Wakatani can well be represented as a beautiful, towering
mountain, like Mt. Fuji. The analogy is further appropriate
since he stood at the summit of the fusion effort, his research
was of zenith quality, and he was at the peak of his powers
when he was unexpectedly taken from us.
Speaking for ourselves personally, but also on behalf ofthe entire worldwide community of fusion plasma physicists– we have lost a valuable scientific colleague and a closefriend. Masahiro Wakatani is greatly missed. We will always
honor his memory with deep respect and genuine affection.

References[1] The electronic file for this talk is posted at http://peaches.ph.utexas.edu/ifs/jift/.
[2] T. Obiki, J. Plasma Fusion Res. 79, 191 (2003) inJapanese. This obituary is also posted at http://
jspf.nifs.ac.jp/7902tuitou/.
[3] S. Hamaguchi, A. Hasegawa and J.W. Van Dam,
“Masahiro Wakatani,” Physics Today, p. 91 (November
2003).
[4] M. Wakatani and R. Itatani, “Collisional diffusion in a
toroidal pinch,” J. Phys. Soc. Jpn. 34, 181 (1973).
[5] M. Wakatani, Nucl. Fusion 18, 1499 (1978).
[6] See, for example, the excellent review paper by M.
Wakatani and S. Sudo, Plasma Phys. Control. Fusion 38,
937 (1996), and references therein.
[7] M. Yokoyama, Y. Nakamura and M. Wakatani, Nucl.
Fusion 34, 288 (1994).
[8] A. Hasegawa and M. Wakatani, Phys. Rev. Lett. 50, 682(1983).
[9] A. Hasegawa and M. Wakatani, Phys. Rev. Lett. 59, 1581
(1987).
[10] G.R. Tynan, M. Burin, C. Holland, G. Antar and P.H.
Diamond, “Radially sheared azimuthal flows andturbulent transport in a cylindrical helicon plasma
device,” to be published in Phys. Plasmas (2004).
[11] See, for example, the references in the review papers by
W. Horton, Rev. Mod. Phys. 71, 735 (1999) and W.
Horton, B. Hu, J.Q. Dong and P. Zhu, “Turbulent
electron thermal transport in tokamaks,” New Journal of7106