Radioisotope Fueled Thermionic Space Power Systems

In order to understand better the interacting variables of the radioisotope fuel properties and the operating conditions for thermionic converters a parametric study was made of the heat source and system variables. Fuel bodies and converters of various geometric shapes were studied with planar, cylindrical, and spherical emitter surfaces. The problems relating to radiological safety and shielding of the isotope fuel were reviewed. Cost and availability information was obtained for some of the more promising isotope fuels. The results of this study show that there is no completely ideal radioisotope heat source for thermionic space power systems and that the more promising isotope fuels will require important compromises between system specific weight, radiation shielding, system efficiency, and isotope containment to produce usable space power systems.