Scientific Discovery via Supercomputing in Plasma Physics

William Tang, Princeton University Chief Scientist, Princeton Plasma Physics Laboratory (PPPL) and Associate Director, Princeton Institute for Computational Science and Engineering

Advanced computing is generally recognized to be an increasingly vital tool for accelerating progress in scientific research during the 21st Century. For example, the Department of Energy’s “Scientific Discovery through Advanced Computing” (SciDAC) Program was motivated in large measure by the fact that formidable scientific challenges in its research portfolio could best be addressed by utilizing the combination of the rapid advances in super-computing technology together with the emergence of effective new algorithms and computational methodologies. The imperative is to translate such progress into corresponding increases in the physics fidelity and the performance of the scientific codes used to model complex physical systems, including those encountered in high temperature plasma research. If properly validated against experimental measurements and analytic benchmarks, these codes can provide reliable predictive capability for the behavior of a broad range of complex natural and engineered systems. This talk reviews recent progress and future directions for advanced simulations with some illustrative examples taken from the plasma physics application area. Significant recent progress in both particle and fluid simulations of fine-scale turbulence and largescale dynamics in magnetically-confined plasmas have been enabled by the combination of access to powerful supercomputing resources together with innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning a huge range in time and space scales. In particular, the plasma science community has made excellent progress in developing advanced codes for which computer run-time and problem size scale well with the number of processors on massively parallel machines (MPPs). A good example is the effective usage of the full power of multi-teraflop (multi-trillion floating point computations per second) MPPs to produce three-dimensional, general geometry, nonlinear particle simulations which have accelerated progress in understanding the nature of plasma turbulence in fusion-grade high temperature plasmas. These calculations, which typically utilize billions of particles for thousands of time-steps, would not have been possible without access to powerful present generation MPP platforms together with modern diagnostic and visualization capabilities to help interpret the results. In general, new insights gained from advanced simulations provide great encouragement for being able to include increasingly realistic dynamics to enable deeper physics understanding of plasmas in both natural and laboratory environments. The associated scientific excitement should serve to stimulate improved cross-cutting collaborations with other fields and hopefully also to help attract bright young talent to the rapidly growing area of interdisciplinary computational science.

Abstract Author(s): William Tang