Scientific and computational challenges of the Fusion Simulation Project (FSP)

This paper will highlight the scientific and computational challenges facing the Fusion Simulation Project (FSP). The primary objective is to develop advanced software designed to use leadership class computers for carrying out multi-scale physics simulations to provide information vital to delivering a realistic integrated fusion simulation model with unprecedented physics fidelity. This multi-physics capability would be unprecedented in that in the current FES applications domain, the largest scale codes are used to carry out first-principles simulations of mostly individual phenomena in realistic 3D geometry while the integrated models are much smaller scale lower dimensionality codes with significant empirical elements used for modeling and designing experiments. The FSP is expected to be the most up-to-date embodiment of the theoretical and experimental understanding of magnetically-confined thermonuclear plasmas and to provide a living framework for the simulation of such plasmas as the associated physics understanding continues to advance over the next several decades. Substantive progress on answering the outstanding scientific questions in the field will drive the FSP toward its ultimate goal of developing a reliable ability to predict the behavior of plasma discharges in toroidal magnetic fusion devices on all relevant time and space scales. From a computational perspective, the fusion energy science application goal to produce high fidelity, whole-device modeling capabilities will demand computing resources in the petascale range and beyond together with the associated multi-core algorithmic formulation needed to address burning plasma issues relevant to ITER – a multibillion dollar collaborative device involving seven international partners representing over half the world’s population. Even more powerful exascale platforms will be needed to meet the future challenges of designing a demonstration fusion reactor (DEMO). Analogous to other major applied physics modeling projects (e.g., ASCI), the FSP will need to develop software in close collaboration with experimental researchers and validated against experimental data from tokamaks around the world. Specific examples of expected advances which are needed to enable a premier comprehensive integrated modeling capability will be discussed.