Radioisotope AMTEC power system designs for spacecraft applications

The authors describe and compare small (two-module) and larger (16-module) AMTEC (alkali metal thermal-to-electric converter) radioisotope powered systems and describe the computer model developed to predict their performance. The high efficiency and static conversion process combined with minimized parasitic losses and operating temperatures that allow the use of current materials while still maintaining a competitive radiator area are found to make AMTEC an excellent candidate for enhanced performance space power systems. AMTEC has the capability of reducing mission costs relative to other static conversion systems because of its high efficiency. AMTEC can also reduce cost relative to dynamic systems simply by being less massive (10 to 5000 W level), and its use eliminates the torque and vibration issues of dynamic systems     

Design and integration of a solar AMTEC power system with anadvanced global positioning satellite

A 1,200-W solar AMTEC (alkali metal thermal-to-electric conversion) power system concept was developed and integrated with an advanced global positioning system (GPS) satellite. The critical integration issues for the SAMTEC with the GPS subsystems included: (1) packaging within the Delta II launch vehicle envelope; (2) deployment and start-up operations for the SAMTEC; (3) SAMTEC operation during all mission phases; (4) satellite field of view restrictions with satellite operations; and (5) effect of the SAMTEC requirements on other satellite subsystems. The SAMTEC power system was compared with a conventional planar solar array/battery power system to assess the differences in system weight, size, and operations, Features of the design include the use of an advanced multitube, vapor anode AMTEC cell design with 24% conversion efficiency, and a direct solar insolation receiver design with integral LiF salt canisters for energy storage to generate power during the maximum solar eclipse cycle, The modular generator design consists of an array of multitube AMTEC cells arranged into a parallel/series electrical network with built-in cell redundancy. Our preliminary assessment indicates that the solar generator design is scaleable over a 500 to 2,500-W range. No battery power is required during the operational phase of the GPS mission. SAMTEC specific power levels greater than 5 We/kg and 160 We/m² are anticipated for a mission duration of 10 to 12 years in orbits with high natural radiation backgrounds     

Radioisotope powered AMTEC systems

Alkali Metal Thermal to Electric Converter (AMTEC) systems are being developed for high performance spacecraft power systems, including small, General Purpose Heat Source (GPHS) powered systems. Several design concepts have been evaluated for the power range from 75 W to 1 kW. The specific power for these concepts has been found to be as high as 18-20 W/kg and 22 kW/m³. The projected area, including radiators, has been as low as 0.4 m²/kW. AMTEC power systems are extremely attractive, relative to other current and projected power systems, because AMTEC offers high power density, low projected area, and low volume. Two AMTEC cell design types have been identified. A single-tube cell is already under development and a multi-tube cell design, to provide additional power system gains, has undergone proof-of-principle testing. Solar powered AMTEC (SAMTEC) systems are also being developed, and numerous terrestrial applications have been identified for which the same basic AMTEC cells being developed for radioisotope systems are also suitable