Hafnium carbide thermal sources in O2, CO and CO2 environments

Abstract

We have tested thermionic cathodes using (210) and (310) oriented hafnium carbide. These have been operated in UHV, and pressures of oxygen, CO₂ and CO to 5 × 10^-5 Torr. Emission data show slight initial improvements due to work function lowering. Relatively stable operation at 1900 K in oxygen or CO₂ at 1 × 10^-6 Torr is reported.