Development of a Hollow Cathode Assembly for the High Voltage Hall Accelerator

Abstract

*† ‡ § The results of the H Igh Voltage Hall A Ccelerator ( HIVHA C) cathode d evelopment task are presented. The goal of th is task was to develop a cathode configuration that operate d in spot mode with minimal keeper power for the prescribed HIVHAC throttle table anode current levels and flow rates . Cathodes with equal cathode tube diameter but varied cathode orifice diameter, keeper configuration, and cathode orifice plate -keeper plate gap were tested. The nominal cathode configuration was that of the International Space Station (ISS ) plasma contactor cathode . The ca thode configuration that best satisfie d the HIVHAC throttle table has a cathode orifice diameter that is 40 % of the ISS plasma co ntactor cathode orifice diameter and a keeper configuration and cathode orifice plate -keeper plate gap identical to that of the ISS plasma contactor cathode . I. Introduction he H Igh Voltage Hall ACcelerator ( HIVHAC ) development program was selected under NASA’s In -Space Propulsion Technology Cycle 2 NASA Research Announcement (NRA) solicitation for “kilowatt solar electric prop ulsion system technology .” NASA Glenn Research Center (GRC) performed mission analysis comparing Hall thruster technology to NASA Evolutionary Xenon Thruster (NEXT) technology for deep space design reference missions (DSDRM) to Saturn and Neptune . The an alysis showed that if a spacecraft uses Hall thruster technology for earth orbit escape and interplanetary transfer, the spacecraft will obtain either a trip time reduction or a payload increase over a spacecraft employing a chemical propulsion system . Ba sed on these findings, NASA GRC proposed to develop a 6-8 kW Hall thruster that operates at a specific impulse of 22 00 -2800 seconds, uses xenon propellant, and has a thrust er efficiency of higher than 62 %. In May of 2003, HIVHAC was selected for award wit h NASA GRC leading partners Aerojet Redmond Rocket Center, the Jet Propulsion Laboratory (JPL), and the University of Michigan. 1 In 2004, the HIVHAC power requirement decreased to 0.3 -2.8 kW in order to expand the applicability of HIVHAC to Discovery clas s missions and New Frontiers class missions . 2