Barium Dispenser Cathode Operation in a Cesium Vapor Environment for Applications in Thermionic Converters

Abstract

Thermionic converters are devices that convert heat directly into electricity with no moving parts. Thermionics require a high current density emission source. Historically, Ba dispenser cathodes have not been used in thermionic converters due to practical limitations surrounding poor background pressure in thermionics. Here we measure the impact of cesium exposure on the performance of a Ba dispenser cathode that that had previously been exposed to air. Measurements indicate that cesium exposure accelerates cathode activation and increases current density, even in the case of unconventionally high base pressures (>10-7 Torr).