Thermionic converters for an Integrated Solar Upper Stage (ISUS)
- Thermacore, Inc., Lancaster, PA (United States)
The Integrated Solar Upper Stage (ISUS) is a solar bimodal system which combines thermal propulsion and electric power generation in a single integrated system. A thermionic converter was designed and fabricated for the ISUS system. The ISUS thermionic energy converters differ from previous designs, due to the significant changes in operating temperature prior to and during an eclipse, with the emitter temperature increasing from 1,900 K to 2,200 K, and then back again. A complete thermal and electrical model was developed for a planar diode to determine optimum operating dimensions and parameters. The model includes an overall energy balance for the diode, and changes the interelectrode gap spacing due to thermal expansion of the parts as the emitter and/or collector temperatures change. Cesium pressure can be chosen from an external liquid reservoir, an integral reservoir using cesium intercalated into graphite attached to the collector heat pipe, or optimum cesium pressure. With optimum cesium pressure, the maximum efficiency increases from 14% to 16% as the emitter temperature increases from 1,900 K to 2,200 K. The improvement in efficiency is only 2% as the emitter temperature is increased. Optimum efficiency requires an external, actively controlled liquid reservoir.
- OSTI ID:
- 438817
- Report Number(s):
- CONF-960805--
- Country of Publication:
- United States
- Language:
- English
Similar Records
GAISUS-1 thermionic converter for the integrated solar upper stage
Dynamic simulation of the thermal and electrical behavior of a thermionic converter coupled to a solar concentrator