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

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.