A Study Program on Cesium Vapor Filled Thermionic Converters Having High Vacuum Work Function Emitter Materials

摘要

Ruthenium, a material having relatively low neutron absorption cross section, was investigated both as an emitter and collector in a thermionic converter. Both hot pressed and plasma sprayed ruthenium emitters were found to behave like high vacuum work function materials (i.e., display high output current densities at relatively low cesium pressures). Significant differences were noted, however, in the performance of the two ruthenium emitters prepared by the different processes. The performance of the ruthenium emitters is compared to that of iridium and rhenium emitters. Generally, the ruthenium data shows a higher output power density, particularly at relatively wide (10 to 30 mil) interelectrode gaps. The ruthenium plasma sprayed collector assumes its minimum value at a temperature which is lower than that for a molybdenum collector by approximately 100K. The value of collector work function at optimum is indicated to be approximately equal for ruthenium and molybdenum. (Author)