Role of anomalous electron transport in a stationary plasma thruster simulation

TLDR

Stationary plasma thrusters use a gas discharge to ionize and accelerate propellant, and experimental electric potential distributions can only be reproduced if anomalous electron transport is stronger outside than inside the channel. The model characterizes the ill‑understood anomalous electron transport in SPTs with empirical parameters and demonstrates their influence on simulation results. The two‑dimensional hybrid model reproduces experimentally measured 10–20 kHz oscillations, predicts additional 100–200 kHz oscillations, and, although optimal parameter values remain unclear, captures many SPT features and shows how these oscillations affect the ion beam energy distribution.

Abstract

Stationary plasma thrusters (SPTs) are advanced propulsion devices that use a gas discharge to ionize and accelerate the propellant. We present simulation results obtained with a two-dimensional hybrid model of an SPT discharge. The model characterizes the ill-understood anomalous electron transport in SPTs by empirical parameters, of which we demonstrate the influence on the simulation results. Although no optimal values for these parameters can clearly be identified, the model predicts many features of the SPT behavior and yields interesting insights in the SPT physics. Experimentally observed electric potential distributions can only be reproduced if the anomalous electron transport is assumed to be stronger outside than inside the SPT channel. The simulations reproduce experimentally measured oscillations at 10–20 kHz and predict additional oscillations at 100–200 kHz. We discuss the dynamics of these oscillations and their influence on the energy distribution of the ion beam leaving the thruster.