Characterization of LaB6 Emitters in an Inductively Coupled Plasma Facility for Electron Transpiration Cooling Applications

A platform was developed to characterize materials for electron transpiration cooling concepts in the University of Vermont 30 kW Inductively Coupled Plasma Facility. In this study we investigate the effect flow speed may have on promoting the convection of electrons from the emitter downstream to the collector. We also investigate a low work function material LaB6 that is commonly used as a robust low work function emitter. We compare these results to baseline performance of POCO graphite emitters. Initial results show that increasing flow velocity does increase measured current levels. We also saw that the LaB6 emitter measurements show appreciably more current than the POCO graphite emitter. This is even with the thermal shock failure and thin surface oxide scale growth of the LaB6 emitter.