RESEARCH ON THERMIONIC CONVERTERS USING BARIUM AND CESIUM VAPOR.
Abstract
Investigations of thermionic converter operations were conducted utilizing a dual vapor system of barium and cesium. Barium and cesium vapors were introduced into two differently designed converters. The first converter developed an internal short circuit due to the development of a low melting point eutectic of barium and palladium which shorted each of the segments of the collector to the base structure. The second converter (tungsten emitter-tungsten collector) was operated for more than 350 hours through more than 40 thermal cycles to gather double vapor I-V characteristics. The converter was operated first with cesium only, to develop several well defined data points at 1600 and 1700 C. The maximum power output measured was 15 watts/sq. cm at 1700 C and at 2-mil spacing. The addition of barium lowered the emitter work function and raised the collector work function as expected. Voltage output losses were observed to increase with increasing barium temperature. Ion generation was believed to be a function of both cesium and barium pressures. The net results was reduced performance with both barium and cesium, generally caused by a reduction in diode output voltage on the order of 0.5 volt. The barium, as well as cesium, appeared to provide ions for neutralization of the space charge. Neutralization was readily observed with very low cesium reservoir temperature (50 C) to an extent greater than predicted. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 15, 1967
- Accession Number
- AD0822913
Entities
People
- Jonathan David Long
Organizations
- Martin Marietta