Researchers led by C.S. Chang of the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have been awarded major supercomputer time to address key issues for ITER, the international experiment under construction in France to demonstrate the practicality of fusion energy. The award, from the DOE's Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program, renews the third and final year of the team's supercomputer allocation for the current round.
Among the largest awards
The proposal was one of the six awards featured in the INCITE announcement of the 47 science projects approved for 2020, and was one of the largest awards.
Fusion, the power that drives the sun and stars, combines light elements in the form of plasma -- the hot, charged state of matter composed of free electrons and atomic nuclei -- that generates massive amounts of energy. ITER represents the next generation experiment of magnetic fusion facilities called "tokamaks" that aim to create fusion on Earth for a virtually inexhaustible supply of power to generate electricity.
"Previous allocations brought us part of the way to predicting ITER's performance," said Chang, whose team uses the high-performance XGC particle code that PPPL has developed to model ITER edge plasma. "This renewal will provide the additional computer time needed."
The third-year allotment consists of 1.5 million node hours on the Theta supercomputer at the Argonne Leadership Computing Facility, and 0.97 million node hours on Summit, the world's most powerful supercomputer, at the Oak Ridge Leadership Computing Facility. Since every computer node has thousands of processing cores, or data processors, a single node hour equals thousands of core hours.
High priority challenges
The multi-year project studies three high-priority ITER edge-plasma challenges:
- Gauging the heat-load that will strike the material surrounding the plasma in ITER. The narrower the heat-load the more damage it could do to metal plates in the divertor that will exhaust waste heat from fusion reactions. Previous high-fidelity studies by Chang's group have predicted that the load could be far wider than other research suggests, and "new simulations will help formulate a new scaling law," Chang said.
- Understanding the physics behind the transition from low-to-high ITER plasmas. A previous Chang team created an earlier model of the spontaneous transition, which will be required for ITER to achieve the goal of producing 10 times more energy than it will take to heat the plasma.
- Studying turbulence at the edge of ITER plasmas that could damage the interior of the fusion facility. Understanding and controlling the "blobby" turbulence at the plasma edge will be crucial to producing fusion energy in ITER.
The INCITE announcement of the renewal called the studies "time-urgent for the successful planning of ITER operation" and ones that require "an intensive, concentrated computing effort using extreme-scale supercomputers."
Members of the Chang team include PPPL physicists Michael Churchill, Stephane Ethier, Robert Hager, Seung-Hoe Ku, Aaron Scheinberg and others. Also participating are members at Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, Los Alamos National Laboratory and Oak Ridge National Laboratory, together with researchers at the University of Colorado Boulder and Denver, the University of California San Diego, The University of Texas at Austin, and Rensselaer Polytechnic Institute.
PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas -- ultra-hot, charged gases -- and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy's Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science.