NERSC Simulations Shed Light on Fusion Reaction Turbulence

HEC Wire September 19, 2017

Understanding fusion reactions in detail – particularly plasma turbulence – is critical to the effort to bring fusion power to reality. Recent work including roughly 70 million hours of compute time at the National Energy Research Scientific Computing Center (NERSC) is helping clarify turbulence behavior characteristics.

A team of physicists from the University of California at San Diego (UCSD), MIT’s Plasma Science and Fusion Center and Princeton Plasma Physics Laboratory (PPPL) ran a series of multiscale gyrokinetic simulations at Lawrence Berkeley National Laboratory’s National Energy Research Scientific Computing Center (NERSC) to determine whether electron energy transport in a tokamak plasma discharge is multiscale in nature.

Visualization of temperature fluctuations from a high-resolution simulation of a plasma discharge in the DIII-D tokamak. The DIII-D plasma was designed to match many of the plasma parameters targeted in ITER operation. Image: Chris Holland

The simulation added strong evidence that electron energy transport is indeed a multi-scale phenomenon. Being able to accurately predict electron energy transport is critical for predicting performance in future reactors such as ITER, a global collaboration to build the largest tokomak fusion reactor, currently under construction in Cadarache, France.

“In a fusion reactor, most of the heat generated in the plasma will be transported by the electrons,” said Chris Holland, a research scientist in the Center for Energy Research at UCSD and lead author on a recent study in Nuclear Fusion describing this work. This study builds on previous research by Holland and colleagues at MIT and General Atomics in which they used multiscale simulations to more precisely study the turbulence instabilities that cause plasma heat loss.

These latest simulations, which were performed with the GYRO gyrokinetic plasma turbulence code and used nearly 70 million hours of computing time on NERSC’s Edison system, corresponded to conditions measured in a plasma run at the DIII-D tokamak reactor using the ITER baseline scenario. Edison is a Cray XC30, with a peak performance of 2.57 petaflops/sec, 133,824 compute cores, 357 terabytes of memory, and 7.56 petabytes of disk.

Link to paper on the work: Gyrokinetic predictions of multiscale transport in a DIII-D ITER baseline discharge

Link to NERSC article: Multiscale Simulations Help Predict Unruly Plasma Behavior