Quasi-neutral Particle Simulations Of Magnetized Low Pressure Discharges,

Abstract

Particle simulations of bulk discharges are constrained by the Debye length scale, which is orders of magnitude less than any other scale length of interest in the bulk plasma. While artificial scaling of the parameters, and nonuniform grid spacing can somewhat alleviate the problem, it still represents a serious constraint. Quasi-neutral fluid and hybrid simulations are routinely done; however in many plasmas on the kinetic nature of both the electrons and ions play important roles. The authors report progress on the development of a quasi-neutral particle simulation for an ECR discharge. The quasi-neutral nature of the plasma means that the algorithms for advancing the ions, electrons and for calculating the electric field are very non-standard. The ions are initially advanced in three dimensions. However very fast time scale, short scale length electrostatic electric fields impose average quasi-neutrality perpendicular to the field. The ion motion in the simulation is slightly corrected to reflect this. Along the field line, quasi-neutrality is maintained by very fast electron oscillations. The electron motion is also slightly corrected to insure quasi-neutrality. Once the particles are convected, the electric field is calculated from the electron momentum equation.