Experimental characterization of the C12A7 hollow cathode and its joint operation with a low-power Hall thruster

Abstract

As essential components of an electrical propulsion system, traditional hollow cathodes, such as BaO-W and LaB6, have stringent requirements on the ignition procedure and propellant purity. The C12A7 hollow cathode with electride inserts, with a reported low work function and resistance to poisoning effects, has shown great potential in replacing traditional cathodes. To avoid the primary problems of frequent melting and degradation of the C12A7 emitter, which might be caused by the heaterless ignition process, a designed C12A7 hollow cathode with a heater was tested and successfully ignited with Xe propellant in this study. The emitting temperature of the C12A7 hollow cathode is estimated to be approximately 1000–1100 °C. The operational characteristics of the C12A7 hollow cathode in diode and triode configurations are presented, including the operating parameters when the discharge mode transition occurred. The C12A7 hollow cathode was subsequently jointly operated with a classic SPT-type Hall effect thruster (HET) for a nominal power of 400W. The HET was specially designed for Iodine propellant and has been tested with a LaB6 hollow cathode. It is successfully ignited by the C12A7 hollow cathode and works stably at 200 W for approximately 3 h. After more than 10 h of operation in a month with multiple exposures to the atmosphere, no obvious degradation of the C12A7 emitter is detected. The experimental results of the C12A7 hollow cathode show comparable performance and fast ignition and thus offer great potential in replacing traditional hollow cathodes, especially in low-power missions.