HIGH TEMPERATURE THERMOELECTRIC RESEARCH

Nominal 50-watt (e) and 15-watt (e) laboratory model generators were designed, fabricated and subjected to sustained and thermal cycling tests at a hot-junction temperature of about 1200C, and cold junctions of about 570C in a vacuum of 10-5 - 10-6 torr. Both generators, constructed of solid-state, bonded, segmented, p- and n-type thermoelements showed good resistance to degradation under these conditions. Improvements in the properties of thermoelectric materials and interface bonding techniques for thermoelements were achieved to yield p-n couples with 17% higher performance, relative to 1962-63 couples. Nuclear reactor, radioisotope, and solar-heated, high- temperature, thermoelectric, spacepowered system concepts were proposed and preliminarily investigated. These studies showed that high-temperature, (1200C) thermoelectric space-type power units, ranging in size from a few watts to several hundred KW output, can be designed for performances from 335 lbs./KW(e) for a solar-concentrating type system to 15 lbs./KW(e) for 350 KW(e) or larger space power systems utilizing fast-reactor heat sources. See also AD422854, AD427285, AD437280.