Parametric design study of ``mini-generator`` with 6-watt heat source

The Fairchild study showed that generator designs based on a single 1‐watt RHU had very poor thermal efficiencies. At their optimum operating point, more than half of the generated heat was lost through the thermal insulation. This resulted in system efficiency of only 2.2%, compared to 7.2% for current Radioisotope Thermoelectric Generators (RTGs). Moreover, there were serious doubts about the fabricability of the required multicouples, particularly of the series/parallel connections between the large number (900) of thermoelectric legs of very small cross‐section (0.21 mm square). All in all, the preceding paper showed that neither JPL’s Power Stick design nor the Fairchild‐generated derivatives based on the 1‐watt heat source looked promising. The present paper describes a similar parametric study of a mini‐generator based on a 6‐watt heat source, and compares its performance and fabricability to that of the optimum Power Stick derivative and of the current RTG design for the same mission.