Micro-power AMTEC systems

There are several terrestrial applications for energy conversion systems wi th electrical outputs of a few volts in the power range from hundreds of mi lliwatts to a few watts. Potential applications include: power for instrume ntation, 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 we describe the development and perform ance of AMTEC systems capable of producing 0.3 to 0.5 watts from a radioiso tope heat source limited to a total thermal output of less than 4 watts. Th e approach utilizes a new "chimney cell" design and a thermal insulation sy stem consisting of a specialized multi-layer insulation (MLI) package in co mbination with fibrous insulation. The cell operates at 0.4 W-c to over 0.5 W-c with an input surface temperature of 700 degreesC. Measurements of the thermal performance of a readily manufactured MLI package indicate that op eration at these temperatures will be achievable with a total heat input of similar to 4 W-th.