Environmental Exposure Impact on High-Current Barium Oxide Cathode Operation

In-space electric propulsion devices use hollow cathode assemblies (HCA) as the electron source for both ionizing the propellant and neutralizing the ion beam. The hollow cathode assembly typically has a cylindrical emitter that emits electrons. Contamination of the cathode emitter can occur during ground activities such as ground tests, handling, transporting, or storing the cathode in an uncontrolled environment. This can have short-term and long-term impacts on the cathode’s performance. Cathode exposure studies carried out at NASA Glenn Research Center (GRC) to understand the impact of emitter contamination on cathode performance have continued with high-current class cathodes. The results of testing multiple cathodes indicate that the impact of contamination experienced during extended exposure at launch conditions is minimal, not only for previously reported low-current BaO cathodes but also for high-current BaO cathodes following proper cathode conditioning.