Arcjet Neutralization of Hall Thrusters. II: Experimental Demonstration

This paper examines the use of an arcjet to neutralize Hall thrusters, as such a hybrid arcjet-Hall thruster concept can fill a performance niche amongst available space propulsion options. We report on experiments that determine how much electron current can be drawn to a surrogate anode from the plume of low power arcjets operating on hydrogen and helium, and demonstrate the first successful operation of a low power Hall thruster-arcjet neutralizer package. In the surrogate anode studies, we find that the drawing of current from the arcjet plume has only a weak effect on overall arcjet performance (thrust), with a slight decrease in arc voltage with increased extracted current. A single arcjet-Hall thruster hybrid package was assembled for concept demonstration. When operating on helium with a nominal mass flow rate of 4.5 mg/s and at very low power levels (70-120W), the arcjet was able to effectively neutralize the 200-900W xenon Hall thruster causing little measurable departure from the hollow-cathode neutralized Hall thruster V-I characteristics up to 250V. At higher helium mass flow rates, the Hall discharge current was slightly perturbed from its expected values, most likely due to the ingestion of helium in the chamber background.