ABSTRACT
Thermionic energy conversion (TEC) is the process of converting heat directly to useful electrical work by the phenomenon of thermionic electron emission. This fundamental concept can be applied to a cylindrical version of the planar converter, considered the building block for space nuclear power systems (SNPS) at any power level. This chapter discusses thermoelectric devices which are based on two transport phenomena: the Seebeck effect for power generation and the Peltier effect for electronic refrigeration. The schematic of a thermoelectric device, or module illustrates the three different modes of operation: power generation, cooling, and heating. The chapter examines design of a thermionic SNPS which is a user-defined compromise between the required output power and the need to operate reliably for a specified lifetime. Based on the type of contact the emitter has with the nuclear fuel, the power systems can be categorized as "incore" or "out-of-core" power systems.
