2002 Fusion Summer Study
Executive Summary

31 July 2002

2002 Fusion Summer Study
Executive Summary
The 2002 Fusion Summer Study was conducted from July 8-19, 2002, in Snowmass, CO,and carried out a critical assessment of major next-steps in the fusion energy sciences
program in both Magnetic Fusion Energy (MFE) and Inertial Fusion Energy (IFE). The
conclusions of this study were based on analysis led by over 60 conveners working withhundreds of members of the fusion energy sciences community extending over 8 months.
This effort culminated in two weeks of intense discussion by over 250 US and 30 foreign
fusion physicists and engineers present at the 2002 Fusion Summer Study. The objectivesof the Fusion Summer Study were three-fold:• Review the scientific issues in burning plasmas, address the relation of burning
plasma in tokamaks to innovative MFE confinement concepts, and address the relationof ignition in IFE to integrated research facilities.
• Provide a forum for critical discussion and review of proposed MFE burning plasma
experiments (IGNITOR, FIRE, and ITER) and assess the scientific and technologicalresearch opportunities and prospective benefits of these approaches to the study ofburning plasmas.
• Provide a forum for the IFE community to present plans for prospective integrated
research facilities, assess the present status of the technical base for each, and establish
a timetable and technical progress necessary to proceed for each.
In the MFE program, the world is now at a major decision point: to go forward with
exploration of a burning plasma, opening up the possibility of discoveries in a plasma
dominated by self-heating from fusion reactions and filling this crucial and now missing
element in the MFE program.
In the IFE program, the decision to construct a burning plasma experiment has already beenmade. The National Nuclear Security Administration is currently building the National
Ignition Facility (NIF) at Lawrence Livermore National Laboratory. The NIF, and otherfacilities worldwide are expected to provide the needed data on inertial fusion burning
plasmas. The IFE questions examined at the Fusion Summer Study revolve about the paceof development of the additional sciences and technologies needed for power production.

Magnetic Fusion Energy
Fusion energy shows great promise to contribute to securing the energy future ofhumanity. The science that underlies this quest is at the frontier of the physics of complex
systems and provides the basis for understanding the behavior of high temperatureplasmas. Grounded in recent excellent progress in the study of magnetically confinedplasmas, the world is now at a major decision point: to go forward with exploration of aburning plasma, opening up the possibility of discoveries in a plasma dominated by selfheating from fusion reactions.
This exciting next step to explore burning plasmas is an essential element in the Fusion
Energy Science Program whose mission is to “Advance plasma science, fusion science andfusion technology—the knowledge base needed for an economically and environmentally
attractive fusion energy source.” The study of burning plasmas will be carried out as part ofa program that includes advancing fundamental understanding of the underlying physics
and technology, theory and computational simulation, and optimization of magnetic
confinement configurations.
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The participants of the 2002 Fusion Summer Study developed major conclusions regarding
the opportunities for exploration and discovery in the field of magnetically confinedburning plasmas. Below are summarized the principal conclusions:
1. The study of burning plasmas, in which self-heating fromfusion reactions dominates plasma behavior, is at the frontierof magnetic fusion energy science. The next major step inmagnetic fusion research should be a burning plasma program,which is essential to the science focus and energy goal of
fusion research.
Study of burning plasmas is a crucial and missing element in the fusion energy sciences
program. It will make a large step forward in demonstrating magnetic fusion as a source ofpractical fusion energy for several applications, e.g., electric power generation andhydrogen production.
The tokamak is now at the stage of scientific maturity that we are ready to undertake theessential step of burning plasma research. Present experimental facilities cannot achieve theconditions necessary for a burning plasma. A new experimental facility is required toaddress the important scientific issues in the burning plasma regime. The conditions needed
to study the key physics phenomena expected in the burning plasma state have been
identified.
Burning plasmas afford unique opportunities to explore, for the first time in the laboratory,
high-temperature-plasma behavior in the regime of strong self-heating. Production of astrongly self-heated fusion plasma will allow the discovery and study of a number of new
phenomena. These include the effects of energetic, fusion-produced alpha particles onplasma stability and turbulence; the strong, nonlinear coupling that will occur between
fusion alpha particles, the pressure driven current, turbulent transport, MHD stability, andboundary-plasma behavior. Specific issues of stability, control, and propagation of thefusion burn and fusion ignition transient phenomena would be addressed.
Recent physics advances in tokamak research, aimed at steady-state and high performance,
demonstrate the potential to significantly increase the economic attractiveness of thetokamak. Therefore, Advanced Tokamak (AT) research capability is highly desirable in any
burning plasma experiment option.
Physics and technology learned in a tokamak-based burning plasma would be transferable
to other configurations. Scientific flexibility, excellent diagnostics, and close coupling totheory and simulation are critical features of a program in burning plasmas. Such a program
would contribute significantly to the physics basis for fusion energy systems based on thetokamak- and other toroidal configurations. The experience gained in burning plasma
diagnostics, essential to obtaining data to advance fusion plasma science, will be highly
applicable to burning plasmas in other magnetic configurations.
2. The three experiments proposed to achieve burning plasma
operation range from compact, high field, copper magnet
devices to a reactor-scale superconducting-magnet device.
These approaches address a spectrum of both physics andfusion technology, and vary widely in overall mission,schedule and cost.
The following mission statements were provided by the proposing teams:
IGNITOR is a facility whose mission is to achieve fusion ignition conditions in deuteriumtritium plasmas for a duration that exceeds the intrinsic plasma physics time scales. It
utilizes high-field copper magnets to achieve a self-heated plasma for pulse lengths
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comparable to the current redistribution time. IGNITOR will study the physics of theignition process and alpha particle confinement as well as the heating and control of aplasma subject to thermonuclear instability.
FIRE is a facility whose mission is to attain, explore, understand and optimize magneticallyconfined fusion-dominated plasmas. FIRE would study burning plasma physics inconventional regimes with Q of about 10 and high-beta advanced tokamak regimes with Q
of about 5 under quasi-stationary conditions. FIRE employs a plasma configuration withstrong plasma shaping, double-null poloidal divertors, reactor level plasma exhaust power
densities and pulsed cryogenically cooled copper coils as a reduced cost approach toachieve this mission.
The overall objective of ITER is to demonstrate the scientific and technological feasibility offusion energy. ITER would accomplish this objective by demonstrating controlled ignitionand extended burn of deuterium-tritium plasmas, with steady-state as an ultimate goal, bydemonstrating technologies essential to a reactor in an integrated system, and by
performing integrated testing of the high heat flux and nuclear components required toutilize fusion energy for practical purposes.
Construction schedules were reported as 5 years for IGNITOR, 6 years for FIRE, and 9
years for ITER. FIRE is not at the same level of readiness as ITER and IGNITOR and will
require some additional time to be ready for construction. ITER must complete international
negotiations and agreement before construction can commence.
Cost information was obtained from the ITER and FIRE teams and was assessed within thelimited resources available for the Snowmass work. All costs were converted to 2002-US
dollars. ITER assumes an international cost-sharing approach while FIRE costs are
estimated as a US project.
• The purpose of the ITER cost information is to provide accurate estimates of therelative “value” of all the tasks necessary for construction to facilitate international
negotiations on task sharing. The cost information is based on a large engineering
effort (about 1000 PPY) and a large R&D effort (about $900M) with prototypes ofall key components. Also, the ITER cost information (about 85 procurement
packages) is based on input from the industries in all the parties. The estimate of the
ITER total “value”, when converted to 2002 US dollars, is about $5 billion. The
actual cost estimate is to be developed by each party using its own procedures,
including the use of contingency. Thus, the ITER cost information does notincluded explicit contingency.
The US will need to carefully estimate the cost of any potential contributions to
ITER. These estimates should include adequate contingency and any additional
required R&D to mitigate against potential cost increases.
• The estimate for FIRE is about $1.2 B including about a 25% contingency. It isbased on an advanced pre-conceptual design using in-house and some vendor
estimates. However, substantial further engineering is needed as well as some
supporting R&D.
• As an Italian project, IGNITOR has been designed in detail with supporting R&D.
It has a detailed cost estimate that is confidential for business purposes and was notmade available to the assessment team.

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3. IGNITOR, FIRE, and ITER would enable studies of the physics
of burning plasma, advance fusion technology, and contribute to thedevelopment of fusion energy. The contributions of the three
approaches would differ considerably.
• IGNITOR offers an opportunity for the early study of burning
plasmas aiming at ignition for about one current redistribution
period.
• FIRE offers an opportunity for the study of burning plasma
physics in conventional and advanced tokamak configurations
under quasi-stationary conditions (several current redistribution
time periods) and would contribute to plasma technology.
• ITER offers an opportunity for the study of burning plasma
physics in conventional and advanced tokamak configurations forlong durations (many current redistribution time periods) withsteady state as the ultimate goal, and would contribute to thedevelopment and integration of plasma and fusion technology.
The three candidate burning plasma devices would contribute a number of key benefits,i.e., capabilities for studies of the physics and technology of burning plasmas (under theassumption that each facility will achieve its proposed performance).
Common benefits from all three candidate burning plasma devices include the following:
PHYSICS
1. Strongly-coupled physics issues of equilibrium, stability, transport, waveparticle interactions, fast ion physics, and boundary physics in the regime ofdominant self-heating.
TECHNOLOGY
2. Plasma support technologies (heating, fuel delivery, exhaust, plasma-facing
components, and magnets) will benefit most because parameters and plasma
conditions will be close to those required for power production.
3. Nuclear technologies (remote handling, vacuum vessel, blankets, safety andmaterials) will advance as a result of the experience of operating in a nuclear
environment. The level of benefit will depend on tritium inventory, pulse
length, duty factor, and lifetime fluence.
Key benefits from IGNITOR are the following:
PHYSICS
1. Capability to address the science of self-heated plasmas in a reactor-relevant
regime of small ρ* (many Larmor orbits) for globally MHD-stable plasmas at
low βN (normalized plasma pressure).
2. Capability to study sawtooth stability at low beta with isotropic alpha particles
and self-consistent pressure profile determined by dominant alpha heating.
TECHNOLOGY
3. Development of high-field copper magnets with advanced structural features,
including bucking and wedging and magnetic press.
4. Development of high-frequency RF antennas for wave heating in a burning
plasma environment.

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Key benefits from FIRE are the following:
PHYSICS
1. Capability to address the science of self-heated plasmas in reactor-relevant
regimes of small ρ* (many Larmor orbits) and high βN (normalized plasmapressure) with a large fraction of non-inductive current sustained for up to a few
current relaxation times.
2. Exploration of high self-driven current regimes with strong shaping and active
MHD stability control.
3. Study of removal of helium ash and impurities with exhaust pumping.
TECHNOLOGY
4. Development of electrical insulation for high-field pulsed copper magnets in ahigh neutron fluence environment.
5. Development of high heat flux plasma-facing components with steady-state heatremoval capability (tungsten/beryllium).
Key benefits from ITER are the following:
PHYSICS
1. Capability to address the science of self-heated plasmas in reactor-relevant
regimes of small ρ* (many Larmor orbits) and high βN (plasma pressure), andwith the capability of full non-inductive current drive sustained in near steadystate conditions.
2. Exploration of high self-driven current regimes with a flexible array of heating,current drive, and rotational drive systems.
3. Exploration of alpha particle-driven instabilities in a reactor-relevant range oftemperatures.
4. Investigation of temperature control and removal of helium ash and impurities
with strong exhaust pumping.
TECHNOLOGY
5. Integration of steady-state reactor-relevant fusion technology: large-scale highfield superconducting magnets; long-pulse high-heat-load plasma-facing
components; control systems; heating systems.
6. Testing of blanket modules for breeding tritium.

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4. There are no outstanding engineering-feasibility issues toprevent the successful design and fabrication of any of thethree options. However, the three approaches are at different
levels of design and R&D.
There is confidence that ITER and FIRE will achieve burning
plasma performance in H–mode based on an extensive
experimental database. IGNITOR would achieve similar
performance if it either obtains H–mode confinement or anenhancement over the standard tokamak L–mode. However, thelikelihood of achieving these enhancements remains anunresolved issue between the assessors and the IGNITOR
team.
The three options are at very different stages of engineering development.
• ITER and IGNITOR have well-developed engineering designs.
• ITER has been supported by a comprehensive R&D program. Also, ITER has
demonstrated full-scale prototypes for essentially all major components of thefusion core and their maintenance.
• FIRE is at the advanced pre-conceptual design level. It has benefited from previous
R&D for CIT/BPX/IGNITOR and, most recently, from ITER R&D.
• IGNITOR has carried out R&D and built full-size prototypes for essentially all
major components.
Projections for the three options are based on present understanding of tokamak physics.
• Based on 0D and 1.5D modeling, all three devices have baseline scenarios whichappear capable of reaching Q = 5 – 15 with the advocates’ assumptions. ITER
and FIRE scenarios are based on standard ELMing H–mode and are reasonable
extrapolations from the existing database.
• IGNITOR’s baseline scenarios, based on cold edged L–mode, depend on a
combination of enhanced energy confinement and/or density -peaking. An
unresolved issue arose as to whether an adequate database exists (proposers) ordoes not exist (assessors) for assessing confinement projections in the proposed
IGNITOR operational modes: L–mode limiter or H–mode with x-point(s) near thewall. Further research and demonstration discharges are recommended.
• More accurate prediction of fusion performance of the three devices is not currently
possible due to known uncertainties in the transport models. An ongoing effort
within the base fusion science program is underway to improve the projections
through increased understanding of transport.
• Each device presents a reasonable set of advanced scenarios based on present
understanding. ITER and FIRE have moderate- and strong-shaping respectively
and the control tool set needed to address the issues of high beta and steady-state
related to Advanced Tokamak regimes. FIRE has the capability to sustain theseregimes for one to three current redistribution times, while ITER has the capability
to sustain these regimes for up to 3000 s allowing near steady-state operation.
IGNITOR presents credible advanced performance scenarios using current ramps
and intense heating to produce internal transport barriers on a transient basis.
A number of issues have been identified and are documented in the body of the report. For
example, on ITER and FIRE, the predicted ELM-power loads are at the upper boundary ofacceptable energy deposition; ELM-control and amelioration is needed. On FIRE, controlof the neoclassical tearing mode by lower hybrid current drive is not sufficiently validated.

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Also, FIRE has a concern about radiation damage of magnet insulators. On ITER, tritium
retention is a concern with carbon-based divertor materials. These issues are the subjects ofcontinuing R&D.
5. The development path to realize fusion power as a practicalenergy source includes four major scientific elements:• Fundamental understanding of the underlying science andtechnology, and optimization of magnetic configurations• Plasma physics research in a burning plasma experiment• High performance, steady-state operation• Development of low-activation materials and fusion technologies
A diversified and integrated portfolio consisting of advanced tokamak, ICCs, andtheory/simulation is needed to achieve the necessary predictive capability. A burning
plasma experiment should be flexible and well-diagnosed in order to provide fundamental
understanding.
Fusion power technologies are a pace-setting element of fusion development. Developmentof fusion power technologies requires:• A strong base program including testing of components in a non-nuclear
environment as well as fission reactors.
• A materials program including an intense neutron source to develop and qualify
low-activation materials.
• A Component Test Facility for integration and test of power technologies in fusion
environment.
An international tokamak research program centered around ITER and including thesenational performance-extension devices has the highest chance of success in exploringburning plasma physics in steady-state. ITER will provide valuable data on integration of
power-plant relevant plasma support technologies. Assuming successful outcome(demonstration of high-performance AT burning plasma), an ITER-based development
path would lead to the shortest development time to a demonstration power plant.
A FIRE-based development plan reduces initial facility investment costs and allows
optimization of experiments for separable missions. It is a lower risk option as it requires“smaller” extrapolation in physics and technology basis. Assuming asuccessful outcome, a
FIRE-based development path provides further optimization before integration steps,
allowing a more advanced and/or less costly integration step to follow.
IGNITOR allows early demonstration of an important fusion milestone, burning plasmas
with a low initial facility investment cost. Because of its short pulse length, IGNITOR
cannot thoroughly investigate burn control and/or advanced tokamak modes. IGNITOR
could be an element of a portfolio of experiments supporting ITER-based or FIRE-based
development scenarios.

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Fig 1. Schematic of development path based on ITER-class burning plasma experiment.

Fig. 2. Schematic of development path based on FIRE-class burning plasma experiment.

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6. A strong base science and technology program is needed toadvance essential fusion science and technology and toparticipate effectively in, and to benefit from, the burning
plasma effort. In particular, the development path forinnovative confinement configurations would benefit fromresearch on a tokamak-based burning plasma experiment.
It has been a much-affirmed premise of the current fusion energy program that astrong base program forms a foundation for the field. The base program develops a broadarray of underlying fusion physics and technology, and provides the knowledge base to
optimize the magnetic configuration for plasma confinement. The science associated withburning plasma science requires a major step beyond the base program. The science
associated with a significant variety of other critical, fundamental issues constitutes the baseprogram.
The base program is also essential to the successful and full exploitation of aburning plasma effort. U.S. participation in a burning plasma experiment clearly requires acadre of fusion physicists and engineers. In addition tokamak experiments are needed tocontribute to the database that helps guide and influence a burning plasma experiment. For
the U.S. to benefit fully from a burning plasma experiment requires not only
experimentalists and engineers, but also theorists and computational scientists who caninterpret the results, and generalize them for application to future tokamak experiments andnon-tokamak configurations.
The development of innovative confinement configurations would benefit from aburning plasma experiment based on the tokamak configuration. Research in innovative
configurations is essential for the broad development of fusion science and for theevolution of an optimal approach to fusion energy. The results from a tokamak burning
plasma experiment will be sufficiently generic to accelerate the development of othertoroidal fusion configurations. The tokamak shares many physics features with thespectrum of toroidal configurations, including nonaxisymmetric tori (the stellarator family),axisymmetric tori with safety factor q > 1 (including advanced tokamaks and sphericaltokamaks), and axisymmetric tori with q < 1 (including the reversed field pinch,
spheromak, and field reversed configurations). The behavior of alpha particles in these
configurations is expected to have features in common, so that tokamak results caninfluence research in other configurations.
There are many geometric differences between a tokamak and these neighboring
configurations; however, if the results from a tokamak burning plasma experiment areunderstood at the level of fundamental physics, then these results can be transferredthrough theory and computation. This transferability is expected to apply to the classicalconfinement of alpha particles, alpha-generated instabilities, the effect of alpha particles on
existing instabilities, the effect of turbulence and MHD instabilities on alpha confinement,
and aspects of burn control. Clearly, the transferability is largest for configurations that are
geometrically closest to the tokamak. However, nearly all physics results obtained in thetokamak configuration have had influence on the large family of toroidal configurations,and it seems clear that this influence will extend to results from tokamak burning plasma
experiments.
The technological information learned from a tokamak burning plasma experimentwill strongly apply to other configurations. Areas of technology transfer include
superconducting magnets, plasma facing components, fueling, heating sources, blankets
and remote handling.

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Inertial Fusion Energy
In 1990 the Fusion Policy Advisory Committee recommended that magnetic fusion energy
and inertial fusion energy be developed in parallel. This policy was reaffirmed by the
Fusion Energy Sciences Advisory Committee in 1999 and The Secretary of Energy
Advisory Board in 2000.
As noted earlier, the programmatic issues facing inertial and magnetic fusion are quite
different. The burning plasma experiments for inertial fusion, namely the National Ignition
Facility (NIF) in the United States and the LMJ in France, are already under construction.
Currently plasma ignition on NIF is expected around FY2010, depending on future
funding decisions about the pace of funding for diagnostics and cryogenic capabilities.
Existing facilities in the United States (e.g., Omega, Z, and Nike) and other facilities
worldwide are providing information leading to burning plasma experiments at the NIF andat the LMJ. The domestic facilities have been built, or are being built, under the auspices of
the National Nuclear Security Administration (NNSA), primarily for defense purposes.
Although the NIF will provide the needed data on burning IFE plasmas, it does not havethe capability to operate at high repetition rates or to manage the fusion power that highrepetition rates produce. Moreover the NIF has neither the efficiency nor the durability
needed for commercial power production. Substantial scientific and technical issues must
be studied and resolved in parallel to enable high repetition rates, good efficiency, andadequate lifetime. The modularity of IFE drivers and the separability of power plantcomponents make it possible to study these issues and issues associated with supporting
subsystems in scaled facilities. The IFE community refers to these facilities as “integrated
research facilities” or IREs. They are the next major steps in inertial fusion. They are
expected to be substantially less expensive than either the magnetic burning plasma
experiment or the NIF. While the NIF can demonstrate the creation of fusion energy insingle shots, the IREs will provide the foundation of science and technology needed for thesubsequent demonstration of net fusion power, and the delivery of net fusion electricity to
the grid.
OVERVIEW OF IFE
An IFE power plant will produce energy by focusing intense beams of light or charged
particles, or concentrating intense x rays, onto a small target containing fusion fuel. The
fuel will ignite with a burst of fusion reactions releasing much more energy than wasinvested to cause ignition. The fusion heart of the power plant will have several importantsystems:•

The fusion targets containing the fuel.

•A factory designed to fabricate millions of targets per year.

•

A chamber approximately 6 meters or more in diameter to capture the energy producedby the fusion pulses.

•

An injection system to inject or place the targets into the chamber.

•

A driver to produce the energy needed for ignition.

•

A focusing or concentration system to deliver the driver energy to the target.

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There are several types of drivers and focusing systems, many different types of targets,and several types of chambers. To some extent these systems or components are
independent so there are many possible combinations. This independence allows modular,
cost-effective research on key issues with synergy among the integrated concepts.
There are currently three main kinds of drivers: heavy ion accelerators, lasers, and z
pinches driven by pulsed power. The drivers are expected to be the single most expensive
part of the power plant. There are substantial research programs in heavy ion acceleratorsand in krypton fluoride lasers (KrF) and diode pumped solid-state lasers (DPSSLs). The
heavy ion fusion program is currently funded through the Office of Fusion Energy
Sciences (OFES) and the laser programs are funded through NNSA. There is a smaller,
concept exploration program in z pinches that builds on an expanding z-pinch programsupported by the NNSA for defense purposes. There are also important IFE programs intarget physics, target fabrication (including mass production techniques), target injection,chambers, and focusing systems. These programs are funded through both OFES andNNSA. Despite different funding sources, all the various inertial fusion research programsare very well coordinated
As noted above, there are many types of targets. In all IFE targets the fusion fuel iscompressed before it is ignited. There are two broad methods of compression and two
methods of ignition. The fuel is compressed either through an implosion driven directly by
the driver beams (direct drive) or by converting the driver energy to x rays that then drive
the implosion (indirect drive). The two classes of ignition are hot-spot ignition and fast
ignition.
Chambers also fall into a number of general types. The types currently receiving the mostattention are dry-wall chambers, wetted-wall chambers, and chambers in which the wall is
protected by thick liquid layers. Often the dry wall chambers contain some gas to protect
the wall from x-rays, charged particles, and target debris. The wetted walls use thin liquid
layers on the wall or sprays of fluid in the chamber to do the same. Thick liquid layers areused to protect the wall from neutrons as well as from x-rays, charged particles, and target
debris.
Although there are many possible combinations of drivers, targets, and chambers,
resources do not allow the exploration of all combinations. Each integrated approach puts
most of its effort into the combination that currently appears to be most compatible. The
various combinations of drivers, targets, and chambers must work together and not all
combinations are equally compatible or self-consistent. Currently the laser programs
emphasize directly driven targets and dry wall chambers. The heavy ion and z pinch
programs emphasize indirectly driven targets and thick liquid wall protection.
IFE PLANS
Several years ago the IFE community developed a program plan or roadmap (Fig. 3)
leading to the integrated research experiments and ultimately to a demonstration power
plant.

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IFE Demo(~1000 MWe)

Results from ETF provide
design basis for Demo?

(Phase III)

Engineering Test Facility(~150 MW e )Power Technologies for Demo

Design basis for ETF from
NIF and IRE programs?
(NNSA/DP funded)• Facility — NIF — and ignition
program• Explore high -yield approaches
Ion beamdevelopment isfunded by
the Office of
Fusion Energy
Science while
High Average
Power Lasers(HAPL) are
funded by NNSA

Integrated ResearchExperiment(s)– IRE –
(Laser and/or ions)

Advanced driverand target R&D
Supporting
technology R&D?
KryptonFluoride
Laser

Diode pumped
Solid -state
LasersTargetdesign &technology
R&D?

Fast Ignitor

Z-Pinches

Ion
Beams
(+ IBX)(Phase II)
Establish design basis
for IRE Program:
Scaled technology
experiments(Phase I)
Concept exploration todetermine potential for amore aggressive program

Fig. 3. The Inertial Fusion Energy Roadmap
This plan has three phases preceding a demonstration power plant. The first phase contains
research elements at the levels referred to as concept exploration and proof of principle. The
IFE community has developed specific milestones that must be met at each level before aconcept is ready to advance to the next step.
Phase I, the current phase of the plan, consists of the research preceding the integrated
research experiments. In this phase there are research programs in target physics, target
fabrication and injection, fusion chambers, and driver physics and technology. The target
physics program includes research on the so-called fast ignition approach; an approach that
may lead to higher target energy gains at reduced driver energy. In Phase I, two laser driverfacilities, Electra and Mercury are under construction and are making excellent progress.
Electra is a krypton fluoride (KrF) laser and Mercury is a diode pumped solid-state laser.
The needed Phase I facility for heavy ion fusion, the Integrated Beam Experiment (IBX),
has not yet been approved. Another driver option, the z-pinch approach, is currently being
studied but does not yet have official Department of Energy funding.
In Phase II, those drivers that meet their milestones advance, using the IREs, to the pointthat the driver information, together with the NIF and advanced research in chambers andtarget technologies provide the information to determine if IFE is ready to proceed to an
Engineering Test Facility (ETF). The ETF will provide a test bed for demonstration of all
IFE plant systems at reduced scale, including tritium breeding and recovery and power
conversion, as well as accelerated materials and component reliability testing. Informationfrom scaled testing of all IFE plant subsystems will be used in decision making todetermine if a full-scale IFE demonstration power plant (Demo) should be built. If thedecision is positive, the ETF will also provide the information that is necessary to design
and build all plant systems in the Demo.

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Assessment of the plans and status at this workshop led to three important conclusions:•

The various driver programs (lasers, heavy ion accelerators, and Zpinches) are advancing at different rates because of funding differences
and their relative maturity. The most advanced programs are unlikely to
be in position to propose an integrated research experiment for several
years.

•The inertial fusion community (both proponents and critics of theindividual approaches) believes that the Phase I research plans are
sound and that they address the correct technical issues.

•

Phase I funding rates are the programmatic issue. Resolution of thisissue will require coordination of the inertial and magnetic programs.

Regarding the second conclusion, it is important to note that there is less agreement about
Phase II and some of the quantitative aspects of the milestones needed to advance to Phase
II. The various disagreements must be resolved by additional workshops and peer review.
Regarding the third conclusion, there are several important points: The laser approaches
have been funded, as a Congressional initiative through NNSA, at approximately the rate
recommended by the Fusion Energy Sciences Advisory Committee in 1999. Nevertheless,there is an important issue: The budgets submitted by NNSA do not contain funding forthese important laser activities so future funding is uncertain. The heavy ion fusion
approach, funded through the Office of Fusion Energy Sciences, has been funded at a little
over half the rate recommended by the Fusion Energy Sciences Committee; and, as noted
above, the IBX has not yet been approved. The z-pinch approach has not been officially
funded and the target physics program (including fast ignition research) is inadequately
funded.
PROGRESS AND ISSUES
Despite the significant near-term issues relating to funding, there has been important
progress since the last Snowmass Summer Study. We conclude with a summary of thisprogress and a summary of some of the important remaining issues:•

Laser systems have made impressive progress in efficiency, pulse rate,and lifetime. Efficiency and lifetime remain important issues for KrF
lasers. Cost of major components and beam quality are important issues
for solid state lasers.

•

The heavy ion fusion program has made excellent progress in basic
beam science. Several new science experiments have recently begun
operations. Fielding integrated experiments (for example the IBX) at
moderate beam energy and current and focusing intense beams in thechamber environment remain the important technical issues.

•

There has been impressive progress in z-pinch targets and good
progress in conceptual power plant designs. Producing economical
recyclable transmission lines at low cost remains the most important
issue.

page 14 of 15•Recent calculations indicate that fluid instabilities in the targets may becontrolled by appropriate choice of pulse shape. Both directly driven
and indirectly driven targets appear to be feasible.

•

Chamber technology and target fabrication and injection are being placedon a sound scientific basis. For example, experiments on dry-walldamage limits are underway. Scaled hydraulics experiments haveidentified nozzle designs that can create all liquid jet configurations
required for thick liquid chambers, and a target injection experiment isunder construction. For heavy-ion fusion there is now a chamber
design where the final focus magnets and chamber structures havepredicted lifetimes exceeding 30 years.

•

There is broad international interest in fast ignition. If fast ignition is
successful, it will produce higher energy gains than conventionaltargets. So far the target experiments have been encouraging,particularly the recent Japanese results. Fast ignition power production
is at a rudimentary level for all drivers. An integrated research plan isrequired.

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