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Exascale computing
to fuel fusion energy
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“The fusion energy science or plasma physics area has been engaged in high-performance computing (HPC) for a long time,” says Tang, who co-chaired a major workshop on the subject sponsored by the Department of Energy (DOE) offices of Fusion Energy Sciences and Advanced Scientific Computing Research. (See sidebar, “Computational challenges in fusion energy research.”) “Some of our applications have computed at the bleeding edge throughout the history of high-performance computing, and that is still the case today.”
In the coming years, computer science and applied mathematicians will have to devise new algorithms to deal with ever-increasing concurrent operation in advanced HPC platforms, along with improved methods to manage, analyze and visualize the torrent of data more powerful simulations and larger experiments, such as ITER, will generate.
They will also need improved formulations for translating the physics of fusion, and other complex natural and engineered systems, into mathematical representations. This includes advanced techniques to develop integrating frameworks, effective workflows and the necessary tools to make comprehensive simulation models run efficiently on exascale machines.
Time-hungry models
Computer simulation is and will continue to be the only game in town for examining some aspects of fusion energy technology, says Zhihong Lin, a professor of physics and astronomy at the University of California, Irvine. “You can do some things (with computers) you can’t do now in experiments, because right now we don’t have burning plasma experiments” like ITER.
Lin leads a DOE Scientific Discovery through Advanced Computing (SciDAC) project to assess the effects of energetic particles on the performance of burning plasmas in ITER. The project has received grants of 20 million processor hours in 2010 and 35 million hours in 2011 from INCITE, DOE’s Innovative and Novel Computational Impact on Theory and Experiment program. The research uses Oak Ridge National Laboratory’s Jaguar, a Cray XT, rated one of the world’s fastest supercomputers.
“We’re always taking whatever computer time we can get our hands on” to make ever-larger simulations, Lin says, because even with millions of hours on supercomputers, models still must simplify the physics behind fusion.
