Two PPPL-led teams win increased supercomputing time to study conditions inside fusion plasmas
Researchers led by scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have won highly competitive allocations of time on two of the world’s fastest supercomputers. The increased awards are designed to advance the development of nuclear fusion as a clean and abundant source of energy for generating electricity.
The allocations marked the second year of three-year grants from a DOE program to accelerate scientific discovery. The nationwide program, called Innovative and Novel Impact on Computational Theory and Experiment (INCITE), awards millions of computer core — or processor — hours for cutting-edge research on energy projects. For example, 100 million core hours on a supercomputer would equal roughly 100 million hours — or 11,000 years — on a desktop computer powered by a single processor. Powering supercomputers, by contrast, are hundreds of thousands of processors that run simultaneously and can accomplish in minutes what a desktop computer would take years to carry out.
The PPPL recipients:
A multi-institutional center led by PPPL physicist C.S. Chang that studies the turbulent edge of the superhot, electrically charged plasma gas that fuels fusion reactions. Chang’s team, the Center for Edge Physics Simulation (EPSI), won a total of 229 million core hours — more than double the 100 million core hours the center received in its first-year and among the top three allotments in the INCITE program. Control of the edge will be crucial for sustaining a fusion reaction in ITER, an international tokamak under construction in France to demonstrate the feasibility of fusion power.
Participants in the center include physicists, mathematicians and computer scientists from PPPL and 10 other U.S. institutions. “We have been making very good progress in both physics and computation,” said Chang, whose EPSI team is developing a high-performance computer code to simulate the edge of the plasma in donut-shaped fusion facilities called tokamaks.
The team recently succeeded in modeling “blobby” — or intermittent — nonlinear plasma-edge turbulence for the first time using the so-called gyrokinetic simulation method, which captures the complex dynamic behavior of plasma particles. Such studies had only been done in the past using simple fluid-modeling codes. The researchers employed most of the nodes of central-processing and graphical-processing cores on “Titan,” the Cray XK7 supercomputer at Oak Ridge National Laboratory, to carry out this first fully kinetic simulation of the “blobby” edge turbulence.
The team’s new award consists of 129 million core hours on the Titan, the world’s second most powerful supercomputer, and 100 million core hours on the IBM Blue Gene/Q supercomputer at Argonne National Laboratory. EPSI could consume the time relatively quickly since the team’s comprehensive, high-performance computer codes can utilize hundreds of thousand of cores in a single hour of massively parallel computing. PPPL researchers who will make use of the newly awarded time include Seung-Hoe Ku, Jianying Lang, and Robert Hager.
An international team led by PPPL physicist William Tang that is developing a high-performance code to study the properties of plasma confinement. Such a code will be an essential ingredient for designing an efficient fusion reactor. The team, which includes U.S. and German researchers, won 50 million core hours on the IBM Blue Gene/Q machine at Argonne, up from 40 million core hours in the previous year’s allotment.
“The goal of this project is to gain new insights on confinement scaling by using powerful, world-class supercomputing systems to carry out simulations with unprecedented resolution and temporal duration,” said Tang. “Findings will also address the key question of how the turbulent transport of plasma particles and associated confinement scale from present generation devices to much larger ITER-size plasmas.”
Results from the first year of Tang’s INCITE project found that the improvement in confinement as devices grow larger takes place far more gradually, and with significantly lower loss rates, than less-powerful computer simulations have indicated. These first-year results received a “High Performance Computing Innovation Excellence Award” from International Data Corp. for Tang and physicists Stephane Ethier of PPPL and Bei Wang of Princeton University. Wang highlighted the results in a paper and talk presented at “SC13,” an international supercomputing conference that drew more than 10,000 attendees when it was held in Denver in November.
The supercomputing awards to PPPL were among four 2014 INCITE awards to researchers at Princeton University. Also winning supercomputing time were Emily Carter, the Gerhard R. Andlinger Professor in Energy and the Environment, and a professor of mechanical and aerospace engineering & applied and computational mathematics; and Jeroen Tromp, a professor of geosciences, applied and computational mathematics, and Blair Professor of Geology. Carter and collaborator Lin-Wang Wang of Lawrence Berkeley National Laboratory won 25 million core hours on Titan to simulate processes inside nanosystems—systems measured in billionths of a meter. Tromp, who also is director of the Princeton Institute for Computational Science and Engineering (PICSciE), and co-investigator Olaf Schenk of the University of Lugano, Switzerland, received 100 million core hours on Titan to develop computer models of the interior of the Earth.