Micro-power AMTEC systems

There are several terrestrial applications for energy conversion systems with electrical outputs of a few volts in the power range from 100 milliwatts to a few watts. Potential include: power for instrumentation, communication and device actuation in severe or harsh environments, as well as a variety of low duty cycle monitoring tasks for the military. For cost and/or packaging reasons, some of these applications are severely heat source limited. In this paper, the authors describe the development and performance of AMTEC systems capable of producing 0.3 to 0.5 watts from a radioisotope heat source limited to a total thermal output of less than 4 watts. The approach utilizes a new, `chimney cell´ design and a thermal insulation system consisting of a specialized multi-layer insulation (MLI) package in combination with fibrous insulation. The cell operates at 0.4 W_e to over 0.5 W_e with an input surface temperature of 700°C. Measurements of the thermal performance of a readily manufactured MLI package indicate that operation at these temperatures will be achievable with a total heat input of ~4 W_th