Modeling a Two-Stage High-Power Anode Layer Thruster and its Plume

A model of a two-stage thruster with anode layer is developed based on a two-dimensional hydrodynamic approach. Each stage is considered separately, while the solution of the first stage provides the boundary conditions for the second stage.Current-voltage characteristic of the discharge in thefirst stage is calculated and is found to be in agreement with experiment. In the acceleration channel the plasma-wall interactions are studied and expansion of the high-voltage sheath near the acceleration channel wall is investigated. It is predicted that under the typical conditions the 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. It is shown that near-wall sheath expansion leads to a shorter acceleration region.Wall erosion by the energetic ions is calculated. The erosion profiles and the total erosion rate generally agree well with available experimental data. Plasma flow analysis provides the boundary conditions for the plume expansion study. The plumemodel is partially validated by comparison of the ion current density distribution with experimental data.