Experimental Investigations with a 5-kW-Class Laboratory Model Closed-Drifted Hall Thruster

This final technical report summarizes research conducted at the Plasmadynamics and Electric Propulsion Laboratory (PEPL) to characterize the internal and plume plasma of a closed-drift Hall thruster (CDT). The project was composed of the following segments: 1) a 5-kW-class CDT (P5) was built and characterized in terms of performance and plume divergence; 2) the molecular-beam mass spectrometer (MBMS) was used to measure the ion energy distribution finction and charge state throughout the PS plume; 3) laser-induced fluorescence was used to measure the ion velocity and temperature in the near-field plume; 4) a 35 GHz microwave interferometer was developed to measure plasma oscillations and electron density in the plume; and 5) the near-field and internal plasma of the PS were characterized using the High-speed Axial Reciprocating Probe (HARP) system developed for this effort. The HARP system enabled, for the first time, the insertion and removal of probes from a CDT discharge channel while minimizing perturbation to thruster operation. The magnetic field, electron temperature, ion number density, plasma and floating potential, and Hall current were mapped throughout the PS discharge chamber at two operating conditions. Thruster perturbation, determined by monitoring discharge current, was less than 10% for the majority of measurements.