Cathode Species Contributions to Hall Thruster Plume Dynamics

By operating a Hall thruster with xenon flow through the cathode and krypton flow through the anode, we can spectroscopically distinguish between the cathode and ion emis- sions in the thruster plume. With narrow band-pass filters for well isolated neutral and ion emission lines for both xenon and krypton, we can image cathode neutral atoms or ions separately for this combination of gases. This imaging has revealed a non-uniform distribu- tion of cathode neutrals that changes with different anode discharge conditions, magnetic filed configurations, and facility base pressures. We also observe correlations between the strength of cathode-to-thruster coupling and discharge current oscillations, indicating the role of cathode interactions with thruster performance.