FPN02-48

2002 Fusion Summer Study Concluded

July 23, 2002

Over 280 fusion researchers, including over 30 non-US participants, concluded a two-week Fusion Summer Study in Snowmass, Colorado, on July 19. The gathering provided "a forum for the critical assessment of major next-steps in the (US) fusion energy sciences program," with the aim of providing "crucial community input to the long-range planning activities" undertaken by the US Department of Energy and its Fusion Energy Sciences Advisory Committee (FESAC). A primary focus of the meeting was to review three proposed magnetic fusion burning plasma experiments (Ignitor, FIRE and ITER) and to review progress and plans in the area of inertial fusion energy. The meeting produced six major conclusions in each area, as follows:

For magnetic fusion energy (MFE), the forum concluded:

1. The study of burning plasmas, in which self-heating from fusion reactions dominates plasma behavior, is at the frontier of magnetic fusion energy science. The next major step in magnetic fusion research should be a burning plasma program, which is essential to the science focus and energy goal of fusion research.

2. The three experiments proposed to achieve burning plasma operation range from compact, high field, copper-magnet devices to a power-plant-scale superconducting-magnet device. These approaches address a spectrum of both physics and fusion technology, and vary widely in overall mission, schedule and cost.

3. Ignitor, FIRE and ITER would enable studies of the physics of burning plasma, advance fusion technology, and contribute to the development of fusion energy. The contributions of the three approaches would differ considerably.

(i) Ignitor offers an opportunity for the early study of non-stationary burning plasmas aiming at ignition.

(ii) FIRE offers an opportunity for the study of burning plasma physics in conventional and advanced tokamak configurations under quasi-stationary conditions and would contribute to plasma technology.

(iii) ITER offers an opportunity for the study of burning plasma physics in conventional and advanced tokamak configurations for long durations with steady state as the ultimate goal, and would contribute to the development and integration of plasma and fusion technology.

4. There are no outstanding engineering-feasibility issues to prevent the successful design and fabrication of any of the three 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 an enhancement over the standard tokamak L-mode. However, the likelihood of achieving these enhancements remains an unresolved issue between the assessors and the Ignitor team.

5. The development path to realize fusion power as a practical energy source includes four major scientific elements:

(i) Fundamental understanding of the underlying science and technology, and optimization of magnetic configurations.
(ii) Plasma physics research in a burning plasma experiment.
(iii) High performance, steady-state operation
(iv) Development of low-activation materials and fusion technologies.

6. A strong base science and technology program is needed to advance essential fusion science and technology and to participate effectively in, and to benefit from, the burning plasma effort. In particular, the development path for innovative confinement configurations would benefit from research on a tokamak-based burning plasma experiment.

Further details are posted at the 2002 Fusion Summer Study web site (http://web.gat.com/snowmass/) or may be requested from G. Navratil (navratil@columbia.edu).

The magnetic fusion energy conclusions will be reviewed by a panel of the FESAC, chaired by Prof. Stewart Prager of the University of Wisconsin, at a meeting August 6-8 in Austin, Texas, and by the full FESAC at its September 11-12 in Gaithersburg, Maryland.

For inertial fusion energy, the forum concluded:

1. The National Ignition Facility (NIF) is expected to produce a burning inertial fusion plasma. The National Nuclear Security Administration is currently building the National Ignition Facility.

2. Laser systems for inertial fusion energy have made impressive progress in efficiency, pulse rate, and lifetime. KrF lasers require further improvement in lifetime, and solid-state lasers require improvement in the cost of major components.

3. The heavy ion fusion program has made excellent progress in basic beam science. Several new science experiments have recently begun operations. Integrated experiments at moderate beam energy and current, including focusing intense beams in the chamber environment remain the important technical issues.

4. 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.

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

6. There is broad international interest in fast ignition. If fast ignition is successful, it will produce higher energy gains than conventional targets. 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 is required.

Further details are posted at the 2002 Fusion Summer Study web site (http://web.gat.com/snowmass/) or may be requested from R. Bangerter (ROBangerter@lbl.gov).