Ionization and acceleration processes in a small, variable channel width, permanent-magnet Hall thruster

A 200 W-class permanent-magnet Hall thruster has been operated with different channel widths. A series of experiments have been carried out for each geometry over a broad range of propellant mass flow rates and applied voltages to investigate the impact of a channel cross-section area variation on discharge and plume properties. Measurement outcomes allow calculation of several quantities, namely the propellant utilization, the beam voltage, the equilibrium wall temperature and the energy flux towards the walls. This study reveals that widening the channel of a low-power Hall thruster enhances ionization and acceleration processes and broadens the operating envelope. Two mechanisms are proposed to explain experimental observations. The surface-to-volume ratio decreases with h, which reduces wall-losses. The magnetic field strength near walls increases with h, which leads to a better plasma confinement.