SBIR-STTR Award

Alkali Metal Thermal to Electric Converters (AMTEC) convert heat to electricity at high efficiency without moving parts at temperatures compatible with current solar receiver technology. A Phase I program is proposed which will deliver an integrated, high-temperature thermal storage/high-efficiency AMTEC cell system concepts and a small-scale thermal energy storage (TES) test article for materials compatibility testing. This will begin demonstrating a radiation-tolerant, eclipse-compatible solar AMTEC power systems for medium-earth and geosynchronous orbits. Solar AMTEC systems have the inherent advantage of tolerance to the high-energy radiation environments encountered in MEO and GEO. This Phase I work is directed toward development of high power solar AMTEC systems for future US Air Force (USAF) spacecraft missions using advanced multi-tube AMTEC cells. Successful development will provide AMTEC power systems for USAF missions, such as Space-Based Radar and Integrated Solar Upper Stage, requiring system power output of 10-50 kW, conversion efficiencies over 30%, cell specific powers over 100 W/kg, and system specific powers of 12-14 We/kg in medium-earth and geosynchronous orbits. This program will begin developing the efficient thermal energy storage systems, through basic materials compatibility research, which allow solar AMTEC systems to operate through eclipse phases of various MEO and GEO environments.

Solar AMTEC systems are modular, inherently radiation hard, low mass, and capable of high thermal-to-electric conversion efficiency without moving parts at temperatures compatable with current solar receiver technology. Future USAF missions, such as Space Based Radar and Space Based Laser, require high power, output (50-100 kWe) and high efficiency from solar AMTEC systems. The Phase I program has generated a concept design for a 500 We solar-heated radial AMTEC cell. The cells will employ thermal energy storage (TES) media to provide continuous power through eclipse periods at LEO, MEO, and GEO altitudes. TES materials compatability was also investigated in Phase I. Phase I also investigated novel approaches to creating isothermal conditions on AMTEC electrodes which will be validated both analytically and experimentally for the large beta"-alumina solid electrolyte tubes appropriate for high power applications. The proposed Phase II program will focus on completion and demonstration of a specific 500 We design tailored to high power USAF missions. Cell power densities approaching 150 W/kg are expected in systems with specific power of 12 - 14 W/kg, including all subsystems. A TES/radial cell integration study for future system ground testing relevant to high power missions will be performed.

Benefits:
If successful, this program will develop 500 - 1,000 Watt AMTEC modules that can be assembled into solar driven, power systems capable of enabling satellite operations requiring electric power delivery at 50 - 100 kWe, at MEO and GEO altitudes. In addition to high power AF missions, a wide variety of commercial satellite and terrestrial applications can also be supported. The program is designed to produce demonstration hardware at the 500 We level