A Novel Technique for the Numerical Simulation of Hot Collision-Free Plasma; Vlasov Hybrid Simulation

Abstract

This paper reports a simple novel technique for the numerical simulation of hot collision-free plasmas. The method is termed Vlasov hybrid simulation (VHS). A time varying phase space simulation box and grid are defined, and the phase fluid within the box is filled with simulation particles. The distribution function F (or δF) is defined on the phase trajectory of each particle. At each timestep F (or δF) is interpolated from the simulation particles onto the phase space grid. Particles are followed continuously until exiting from the phase box and are not constantly recreated at phase space grid points. The algorithm is very efficient, stable, and has low noise levels. Distribution function fine structure is tolerated and the formalism does not require diffusion of the distribution function, The VHS method is particularly valuable when the flux of phase fluid across the phase box boundary is significant. In this case VHS codes have a dynamic population of particles—giving great efficiency gains over PIC codes with fixed particle populations. The VHS method has been applied to the numerical simulation of triggered VLF emissions in the magnetosphere and gives results in close agreement with observations.