With OLCF resources, Fox is replicating the behaviors of astrophysical plasmas 

Will Fox, a research scientist at the US Department of Energy’s (DOE’s) Princeton Plasma Physics Laboratory (PPPL) and long-time user of the Oak Ridge Leadership Computing Facility (OLCF), has received the 2019 Thomas H. Stix Award for Outstanding Early Career Contributions to Plasma Physics Research from the American Physical Society.

Will Fox of Princeton Plasma Physics Laboratory examined the relationship between high-density plasma and magnetic fields. Credit: PPPL

Using the Titan supercomputer at the OLCF, a DOE Office of Science User Facility at DOE’s Oak Ridge National Laboratory, Fox and his team were able to simulate the behavior of high-energy-density plasmas, which are used in laboratory experiments that study fundamental plasma processes that may explain several mysteries in cosmic plasmas. Key questions for plasma astrophysicists include how the ubiquitous magnetic fields of the cosmos are generated and what role they play in accelerating particles to enormous energies.

The researchers studied how magnetic fields are generated in these plasmas by the Biermann battery effect and Weibel processes. They also studied, by merging two magnetized plasmas, how the magnetic fields could violently dissipate through a process called magnetic reconnection that accelerates high-energy particle populations. Magnetic reconnection gives rise to phenomenon such as northern lights, solar flares, and geomagnetic space storms.

Finally, reconnection showed how colliding supersonic plasmas can form collisionless shocks, which occur, for example, in exploding supernova and may be responsible for the acceleration of cosmic ray particles to extreme energies.

Fox is a primary developer of the first-principles particle-in-cell Plasma Simulation Code, and his simulations on Titan have proven crucial in designing and making predictions to compare with the experiments.

A unifying theme of the work is that the plasma processes occur in both the laboratory and cosmos with few collisions between plasma particles. Kinetic simulations track the individual particles in the plasma and their self-consistent evolution with electromagnetic fields. Such kinetic simulations with experimentally relevant parameters and geometry require leadership-scale computation on machines such as Titan.

 UT Battelle LLC manages ORNL for the US Department of Energy’s Office of Science. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, New Jersey, 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. Princeton manages PPPL for the Office of Science.

 The Office of Science is the largest single 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, please visit https://energy.gov/science.