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Applied Plasma Physics and Fusion Energy Seminar Series

Fall 2002

Tuesday, 3:30-4:30 PM in 479 EBU-II


October 22

Jill Dahlburg
General Atomics

ABSTRACT:

Fusion is a potentially inexhaustible energy source whose development entails understanding complex plasmas under extreme conditions. The development of a science-based predictive capability for high temperature, fusion-relevant plasmas is a challenge central to fusion energy science. The combination of extreme separation of time and spatial scales, extreme anisotropy, the macroscopic effects of microscopic physics, the importance of geometric detail, and the requirement of causality makes this problem among the most challenging in computational physics. The exponential growth of computational capability, coupled with the high cost of operating large-scale experimental facilities, makes the development of a fusion simulation initiative a timely and cost-effective opportunity.

Numerical modeling has played a vital role in magnetic fusion for over four decades, with increases in the breadth and scope of feasible simulation enabled by improvements in hardware, software and algorithms. Currently, sophisticated computational models are under development for many individual features of magnetically confined plasmas. However, full predictive understanding of fusion plasmas also requires cross-coupling of a wide variety of physical processes. While integrated models using simplified descriptions of a number of physical processes exist and have been widely used in the program, the capabilities needed for full predictive simulation and optimization of a burning plasma require major qualitative improvements in physics models, algorithms, computational platforms, and the ability to integrate codes from a large number of research teams working on different elements of the problem. An integrated simulation capability would dramatically enhance the utilization of such a facility and the optimization of toroidal fusion plasmas in general.

Recently, the US DOE Fusion Energy Sciences Advisory Committee, the FESAC, recommended that a major new programmatic initiative be undertaken, referred to as the Fusion Simulation Project (FSP); please see http://www.isofs.info for a copy of the interim report that was delivered to the Office of Science in July, 2002. The purpose of the initiative is to make a significant advance within five years toward the ultimate objective of fusion simulation - to predict accurately the behavior of plasma discharges in a toroidal magnetic fusion device on all relevant diverse time and space scales. This is in essence the capability for carrying out "virtual experiments" of a burning magnetically confined plasma, implying predictive capability over many energy-confinement times, faithful representations of the salient physics processes of the plasma, and inclusion of the interactions with the external world (sources, control systems and bounding surfaces).

In the same time frame as the above-quoted FESAC recommendation was issued, U.S. fusion physicists met to plan the next stage of their research, the creation of the first burning plasma experiment (in the laboratory). This will be a true, experimental fusion reactor, perhaps the proposed International Thermonuclear Energy Reactor. A product of this 2002 Snowmass Fusion Summer Study meeting was the Snowmass Development Pathway Subgroup: Development Path Scenarios document. In this report, fusion pathway planners recommended that the five major next step plasma physics facilities in the International Portfolio Approach for Burning Plasma Physics and Configuration Optimization should be: (1) advanced tokamak physics facilities; (2) burning plasma facility(s); (3) a Fusion Plasma Simulator; (4) non-tokamak facilities; and, (5) a strong base program. In particular, the Fusion Plasma Simulator is envisioned 'to contain comprehensive coupled self-consistent models of all important plasma phenomena that would be used to guide experiments and be updated with ongoing experimental results. Most importantly, the FPS would serve as the intellectual integrator of physics phenomena in advanced tokamak configurations, advanced stellerators and tokamak burning plasma experiments. It would integrate the underlying fusion plasma science with the Innovative Confinement Concepts thereby accelerating their development. This is envisioned as a major long term effort requiring additional resources of about $0.4B over a 15 year period.'

This seminar describes the FSP planning activities to date, and provides a forum for input to the FESAC ISOFS Subcommittee regarding suggestions for FSP goals and strategies. The final FESAC report of the ISOFS planning activity is due to Dr. Ray Orbach (DOE Office of Science) on 1 December, 2002.

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