The Saha Equation for a Two-Temperature Plasma

Abstract

A generalization of the Saha equation for the case of a two-temperature plasma is derived from thermodynamic considerations. The resulting equation depends in first approximation on the electron temperature only. A more rigorous approach concerns the application of the Zubarev formalism. This is done for arbitrary heat flow between the electrons and the internal states of the heavy particles on one hand and the kinetic degrees of freedom of the heavy particles on the other hand. In the case of zero heat flow the equation mentioned with electron temperature only is recovered. In general corrections to this are found which depend on the ratio of electron and heavy particle masses, the temperature difference and the specific atomic structure. For hydrogen plasmas the results indicate that corrections may be of the order of 10%.