Endurance operation of a heaterless C12A7 electride plasma cathode and post operation material analysis

A heaterless plasma cathode using disc shaped C12A7 electride as emitter material is being developed for electric propulsion systems in space. C12A7 electride is a calcium-aluminate ceramic (12CaO center dot 7Al2O3) with a low work function of about 2.4 eV. The material has been optimized for improved thermionic emission and discharge stability. Due to the low work function of the emitter material, the cathode can be easily ignited from room temperature, eliminating the need of a complex and delicate heater. The cathode has been operated continuously for more than 950 h with the results being presented. After this endurance operation, a detailed material analysis (phase composition and microstructure) has been conducted and is presented.