Thermal Energy Storage and Heat Transfer Support Program. Task 4. Thermionic Energy Conversion Studies. Volume 2

This report provides the technical details on the research activities for Task - 4 on the fabrication and utility installation for the three thermionic diode test stations and the diode processing station are discussed along with the instrumentation for actually testing the diodes. Experimental results as well as analytical characterization results have been provided in the form of J-V characteristics and discrepancies between the two have been explained. Emitter temperature calibration results have also been provided. Efforts are currently directed towards developing an automated pulse generating circuit to sweep (voltage) the diminiode and generate in ignited mode J-V characteristic in less than 5 msecs thereby taking advantage of the converter's thermal inertia properties. Performance verification tests were conducted on a planar diminode with sintered Lanthanum Hexaboride as the emitter material and arc melted Lanthanum Hexaboride as the collection material. It was found that the performance of the diode was well in agreement with similar characteristics generated earlier.