Model of the Plasma Flow in High-Power TAL

Abstract

Recently great emphasize was put forward int o high power Hall thruster development. Among Hall thruster technologies, the thruster with anode layer (TAL) seems to have much wider technical capabilities. In this paper, various aspects of the plasma flow in a high power thruster with anode layer are studied. A model of plasma flow in the TAL channel is developed based on a 2D hydrodynamic approach. In particular, plasma –wall interactions are studied in detail. Formation of the sheath near the acceleration channel wall and sheath expansion in the accel eration channel are calculated. Both single and two -stage TALs are investigated. It is found that the high voltage sheath expands significantly and the quasi -neutral plasma region is confined in the middle of the channel. For instance, in the case of a 3 kV discharge voltage, the sheath thickness is about 1 cm, which is a significant portion of the channel width. An effect of sheath expansion on the acceleration region is studied using a quasi 1D simplified model. It is found that sheath expansion decrease s the acceleration region length. The single stage, high voltage TAL (D -80) is studied. The model predicts a non -monotonic behavior of thruster efficiency with discharge voltage. The location of maximum efficiency is found to be in agreement with experimen t.