Efficiency of the Plasma Thermocouple

Abstract

The efficiency of a thermionic converter containing cesium ions is calculated for the regime, in which the plasma density is sufficiently high so that the random current density, nev̄/4, is large compared to the actual current density. Under these circumstances, positive space charge barriers are set up at the electrodes, and the plasma region is many free paths in length. The output voltage V is determined for various currents by a consistent solution of the electrical and thermal conduction problems. The efficiency of the thermocouple is then deduced from the calculated current‐voltage characteristic and the appropriate electron temperature distribution. Overall efficiencies up to 32% are predicted for a typical thermocouple circuit.