Issued patent
Portable Compact Thermionic Power Cell
An issued NASA patent from the Technology Transfer catalog.
About this technology
Overview
Ideal power sources for portable equipment ideally should be small, compact, lightweight, and provide continuous power with high power density. Batteries meet all but the continuous power requirement. Radioisotope thermoelectric generators (RTG) meet the continuous power condition but none of the others. However, a compact, thermionic-based cell that converts heat to electricity can meet all the above requirements . A tightly spaced array of nanometer-scale emitter points efficiently converts the heat from Plutonium-238 (238 Pu) into usable electricity. The thermionic cell uses metals with low work-function, not semiconductors, and escapes many of the RTG limitations such as lower carrier concentration and mobility, and the difficult requirement of high electrical and low thermal conductivity. It delivers an estimated 10-20% vs. 7% efficiency for an equivalent-sized, 238Pu-based RTG. Such a power cell would be ideal for remote, hazardous or otherwise isolated applications such as remote sensors/transmitters in severe environments.