Power Converters for Spacecraft
For over 30 years, NASA has used radioisotope thermoelectric generators (RTGs) to provide electrical power on a range of space exploration missions. Creare engineers are working with NASA on alternative radioisotope power conversion technologies. This is an ambitious attempt to improve the power conversion efficiency and reduce the weight and cost of the next generation of radioisotope power systems.
Creare has considered two alternative power conversion systems, one dynamic and the other static, that promise to improve conversion efficiency by a factor of two to four and reduce weight by a factor of two to three. Both of these projects have included demonstrations of breadboard power converters.
Dynamic power conversion concept is based on miniature turbomachinery technology used to compress and expand the working gas in a Brayton cycle at high temperature. The technical challenge for this system is the fabrication of miniature, high-speed (>150,000 rpm) rotating turbomachinery that operates at high temperature (1100 K) at the turbine end of the common shaft and at near-ambient temperature (350 K) at the compressor end. |
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Creare’s static power conversion system uses thermophotovoltaics (TPV) to convert radiant energy from the radioisotope heat source directly into electricity. The technical challenges for this concept include the fabrication of high-temperature (1350 K) emitter structures and the thermal design, development, and fabrication of converter hardware, advanced photovoltaic cells, and advanced filters to maximize efficiency.
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