Two-dimensional hybrid-direct kinetic simulation of a Hall thruster discharge plasma

A direct kinetic (DK) simulation is capable of modeling the nonequilibrium state of plasma as it evolves in the discharge region of a Hall thruster without the numerical noise that is inherent to particle-based methods since the velocity distribution functions are obtained in a deterministic manner. In this work, a hybrid-DK simulation utilizes a quasi-one-dimensional fluid electron model in conjunction with a two-dimensional DK method to simulate neutral atoms and ions in a Hall thruster channel and near-field plume. Instantaneous and time-averaged plasma properties calculated using the hybrid-DK simulation are benchmarked against the results obtained from a two-dimensional hybrid-particle-in-cell (PIC) simulation with an identical fluid electron model. For both high and low-frequency oscillations, the two simulations show good agreement for time-averaged and dynamic plasma properties. Numerical noise tends to randomize plasma oscillations in the PIC simulation results, whereas the DK results exhibit coherent oscillatory behavior.