Design of conductively coupled multi-cell thermionic fuel element

Design and fabrication of a novel multi-cell thermionic fuel element (TFE) is in progress. The multi-cell approach helps minimize ohmic losses in the electrodes by reducing the electrode area of each cell. Series connected small cells result in higher output voltage and lower ohmic losses. A critical component is the intercell connector, which must accommodate any thermal expansion mismatch between the emitters and collectors and minimize electrical and thermal losses. Three designs for the intercell connector were evaluated. The multi-cell TFE incorporates one continuous fuel clad that is accessible with a single full-length TFE heater and is therefore testable with an electric heater. Furthermore, a multi-cell TFE system can be scaled to multi-megawatt power levels. With moderate design changes, the multi-cell concept can be incorporated into a solar thermal power system.