Data-Driven Estimation of Electrical Facility Effects on Anomalous Electron Transport in Hall Effect Thrusters

Past studies have demonstrated that a global ionization oscillation, referred to as the breathing mode, is one of the dominant oscillations in Hall effect thrusters over a wide range of operating conditions. It has been experimentally observed that plasma properties, including the anomalous electron mobility, and current collected at the conductive walls of the vacuum chamber test facility oscillate periodically in time. To study the coupling that occurs between the anomalous electron mobility and the test facility electrical configuration, a zero-dimensional (0D) global plasma ionization oscillation model of a Hall effect thruster is combined with a circuit model of a vacuum chamber test facility. The ion and neutral number densities, electron temperature, ion and electron velocities, and a minimal set of circuit parameters (i.e., current or voltage) are estimated. An extended Kalman filter (EKF) allows for the estimation of anomalous electron mobility using time-dependent experimental data. The effects of the electrical circuit on the plasma oscillations will be discussed.