The urgent need for the Fusion Simulation Project is motivated by the fact that there are significant physics problems associated with ITER discharge scenario planning and control. Between now and the time that ITER construction is completed, controls must be developed to suppress large scale instabilities that can adversely affect confinement in ITER. Accurate predictions are needed for the edge transport barrier that enhances the core plasma confinement and for the edge instabilities that cause fluctuations in power to the divertor and first wall. Since each discharge in ITER is expected to cost about a million dollars, there will be a strong need to use whole device computer simulations to optimize discharge scenarios. It is be essential to have a fully verified and validated comprehensive integrated modeling capability to support ITER and other current and planned tokamaks.
An evolving opportunity for the Fusion Simulation Project results from the fact that computer hardware and software are rapidly evolving beyond all previous expectations. Within the next five years, we will be in the age of petascale computing (1015 FLOPS). High performance computing has been applied during the first round of SciDAC projects to the investigation of individual physical phenomena, such as turbulence or large scale instabilities, using first principles computations. A second round of SciDAC projects has been initiated to consider the pair-wise interaction of physical phenomena, such as the interaction between radio frequency heating and large scale instabilities. The intention of the Fusion Simulation Project is to use high performance computers to carry out whole device modeling in which many physical processes interact simultaneously and self-consistently. It is expected that comprehensive whole device modeling will be validated against tokamak experimental data and will be used for discharge scenario modeling and for the design of control techniques in the forthcoming ITER experiment.