Search Results

AMTEC systems have historically been operated with sodium as the working fluid, in large part because fabrication of beta”-alumina solid electrolyte (BASE) membranes has been substantially easier with sodium than with potassium or other alkali metals1. It has been anticipated that because potassium has a substantially higher vapor pressure for a given temperature, and because the best K-BASE conductivity falls only marginally below that for Na-BASE, potassium AMTEC cells could produce higher power at a given temperature or comparable power at a lower temperature than similar sodium cells. Operation at lower temperatures can reduce materials lifetime or compatibility problems, and for severely heat input constrained systems it could enhance efficiency by reducing parasitic thermal conduction losses. Recently K-BASE tubes have become available as a commercial product2 and conventional experiments to evaluate the performance of complete KAMTEC cells have become much more feasible.

An Advanced Radioisotope Power System (ARPS) in the 150 watt class is currently under development for space applications. The ARPS is a potential power source for potential NASA missions to Europa in 2003 and Pluto/Kuiper in 2004. The ARPS system, which has been described in recent literature (Hendricks, 1997), will utilize a multi-tube Alkali Metal Thermal to Electric Converter (AMTEC) cell design. Designated EPX-1, the cell is designed to survive ground handling and launch stresses and provide reliable power for the duration of the missions. The EPX-1 AMTEC cell is based on the PX series of demonstration cells (Borkowski, 1997, and Sievers, 1998). The planned operating temperatures and life requirements for these missions have made an all refractory metal design a requirement. Several other design enhancements have been implemented to meet specific mission requirements and improve predicted cell reliability.