Particle Simulation Studies on Behaviour of Rapidly-Expanding High-Beta Plasma Column in a Uniform Magnetic Field

Abstract

The macroscopic and microscopic behaviour of a plasma column with an extremely high initial plasma-beta in a uniform axial magnetic field has been studied by means of a “two-and-a-half-dimensional”, magnetostatic, collisionless particle simulation code. This study has been motivated by the results of laser-produced plasma experiments in magnetic fields. It includes not only a rapid initial plasma expansion but also subsequent complex phenomena such as the “re-thermalization” process, the formation of a high-beta sheath and the onset of flute-like plasma instability. The results found by the present simulation on the formation of “crater-wall-like” structures in both the plasma density and internal energy in the re-thermalization stage, the formation of the high-beta sheath with a thickness of the order of the “hybrid” Larmor radius (“Rosenbluth-sheath”) and a growth-rate of the instability nearly equal to that of the lower-hybrid-drift instability all appear to be consistent with the results of laser-produced plasma experiments hitherto performed by the present authors' group.