Modeling of a high-power thruster with anode layer

Abstract

Among Hall thruster technologies, the thruster with anode layer (TAL) has much wider technical capabilities, especially in the high-power regime of operation. In this paper, various aspects of the plasma flow in a high-power thruster with anode layer are studied. Based on a 2D hydrodynamic model, the formation of a space-charge sheath near the acceleration channel wall and the sheath expansion in the acceleration channel are calculated. It is found that the high-voltage sheath near the channel wall expands significantly and the quasineutral 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 (which is typically a few cm). In addition, a simplified quasi-1D model is developed to study the anode acceleration layer, which is confined by channel walls. It is found that near-wall sheath expansion leads to an increase in current density along the channel, and this in turn causes decrease of the acceleration region length. This is an important finding as it has implications for high-power TAL behavior, in which contact of the plasma with acceleration channel walls can be limited.