High Current Cathode Development for 50 kW Class Hall Thrusters

Abstract

50 kW class Hall thrusters developed at NASA G lenn Research Center (GRC) requir ed holl ow cathodes to operate at emission currents up to 100 A. Future Hall thruster designs may operate at over 100 kilowatts , requiring cathodes capable of operating at emission currents over 200 A. A test program was undertaken to det ermine the hollow cathode geometr y needed to meet the se high emission current requirements while provid ing long life. To enable this, a laboratory model hollow cathode assembly with a reconfigurable geometry was designed and characteriz ed at emission curr ents up to 100 A . This cathode design incorporated some characteristics of the NASA plasma contactor design but was modified for integration along the central axis of a Hall thruster. The reconfigurable geometry allowed for variation of the following par ameters: cathode orifice size, emitter & cathode diameter, cathode -keeper spacing , and propellant flow rate. Cathode temperature s were measured to determine the optimal geometry for an emission current of 100 A.