Theory Seminar: A deep dive into the distribution function: understanding phase space dynamics using continuum Vlasov-Maxwell simulations

James Juno

University of Maryland, College Park

Wednesday, September 25, 2019



PSFC Seminars

Abstract: In collisionless plasmas, the particle distribution function is a rich tapestry of the underlying physics. However, actually leveraging the particle distribution function to understand the dynamics of a collisionless plasma is challenging, both because the Vlasov-Maxwell system of equations is a difficult equation system to numerically integrate, and traditional methods such as the particle-in-cell method introduce counting noise into the distribution function. Using a novel continuum Vlasov-Maxwell method implemented in the Gkeyll framework, I will present the phase space dynamics of a number of plasma instabilities. In particular, I will focus on the competition of small scale kinetic instabilities driven by unstable beams of plasma, and present a set of results where the generation of small scale structure in velocity space affects the overall macroscopic evolution of the plasma. I will also briefly discuss the computational challenges in developing a continuum Vlasov-Maxwell code, and motivate my efforts to develop this code by demonstrating how particle noise modifies the dynamics of the same set of simulations.


Bio: James (Jimmy) Juno received his B. Sc. in computational physics from Rice University in 2014. He is currently a Ph. D. candidate at the University of Maryland, College Park, working under the supervision of Professor Bill Dorland, and a visiting graduate student at the Princeton Plasma Physics Lab.

At the Princeton Plasma Physics Lab, he works with Dr. Ammar Hakim and Dr. Jason TenBarge in the Gkeyll project, developing the continuum Vlasov-Maxwell solver within the Gkeyll code for the simulation of instabilities and turbulence in space and astrophysical plasmas. His thesis work involves leveraging the high fidelity representation of the particle distribution function provided by a continuum Vlasov-Maxwell solver to understand detailed phase space dynamics.