Estimation of in-space thruster performance of a Hall effect thruster through extrapolation of plasma states using extended Kalman filter

Abstract

Prediction of in-space operating conditions from measurement data obtained in ground tests, i.e., in vacuum chambers, plays an important role for spacecraft electric propulsion systems. Typically, the in-space thruster performance, such as thrust and dynamic behavior, is predicted by extrapolating the thruster performance data obtained with different background pressures in ground tests to the zero-background pressure limit. In this paper, we propose a computational framework where the underlying plasma states of the ground tests are first estimated, which are then extrapolated to evaluate the thruster performance at zero background pressure. The time-dependent plasma properties in a Hall effect thruster are estimated using discharge current and thrust measurement at different background pressures using an extended Kalman filter with a 0D global model. The numerical results suggest that the phases of the ion density, ion bulk velocity, and electron bulk velocity oscillations are functions of the background pressure. Using the extrapolated plasma estimates, the time average and oscillation amplitude of the discharge current and thrust are evaluated at zero background pressure, providing a prediction of the time-dependent thruster dynamics in the zero pressure limit.