Influence of kinetic effects on long wavelength gradient-drift instability in high-frequency range in Hall thruster

Abstract

A typical for Hall thruster discharges strong inhomogeneity of plasma parameters is a source of various types of instabilities. Some types of such instabilities (long high-frequency waves, in particular) are assumed to contribute to anomalous electron conductivity, which is essential to understand for the development of a reliable modelling tool for Hall thrusters. In this paper, the results of an analytical study of the influence of kinetic effects on dispersion properties of high-frequency perturbations in Hall thruster plasmas are presented, including the effect of the gradient magnetic electron drift on the long wavelength high-frequency instability. It was shown that when the long waves with phase velocity on the order of the unperturbed electron drift motion occur, the electron guiding center deviates significantly from the electric field equipotential line. The observed phenomenon leads to a self-sustained cycle of an intensive energy exchange between the waves and the electrons and a long-wavelength high-frequency instability inciting each other.