Correlation between nonequilibrium thermodynamic theory and V-I curves of a thermionic converter

Abstract

The methods of irreversible thermodynamics have been used as a basis for developing a transport theory applicable to thermionic cesium diodes. This theory was applied in describing certain aspects of experimental voltage-current (V-I) characteristic curves of a thermionic diode. Emphasis, in obtaining the description, is placed on the open-circuit voltage and short-circuit current of the V-I curves, obtained at the Jet Propulsion Laboratory. Experimental results show that the open-circuit voltage is essentially independent of the interelectrode spacing, whereas the short-circuit current varies inversely with the interelectrode separation. The inverse dependence is in agreement with the results of this present analysis and also with results expected from diffusion theory, which has been used in other analyses. In fact, the theory used in this present investigation reduces to diffusion theory under special assumptions. Deviations from diffusion theory, which were found in experimental results, can be accounted for using the theory developed in this paper.