Ion Collection in Hall Thruster Plumes

Abstract

HE Hall effect thruster’s (HETs) combination of high specific impulse, efficiency, and thrust density has increased its popularity for use as spacecraft propulsion. Currently, the widespread use of HETs is hindered by the limited understanding of plume interaction with the spacecraft. This situation is complicated by the wide rage of probe designs and test facilities used for HET investigations. This Note reports on two nude Faraday probes of differing design that are used simultaneously to measure the ion current density of a 5-kW Hall thruster. The results show that both probes measure similar thruster plume profiles over the range of angular positions investigated for all operating conditions, with small differences between the ion current density profiles of the probes attributed to material selection. Moreover, both probes measure the highest ion current density near thruster centerline at the highest facility operating pressure. A combination of charge-exchange collisions and vacuum chamber gas ingestion into the thruster is believed to cause this phenomenon. Experimental Apparatus