Segmented electrode losses in MHD generators with nonequilibrium ionization.

Abstract

A theory is proposed which accounts for the effect of Joule dissipation near a segmented electrode wall, on the electrical conductivity near the wall. In MHD generators which are designed to produce nonequilibrium ionization due to electron heating, the elevation of conductivity will occur first near the electrode wall, be cause the Joule heating of the fluid is much greater there than in the free stream. This local increase of conductivity will tend to cause a flow of current in the Hall direction which amplifies the dissipation, and greatly reduces the current density and elevation of electron temperature which can be attained in the generator. A theory is proposed which accounts for these phenomena in predicting generator performance as a function of the usual variables, plus the ideal electron temperature rise. The predicted maximum Hall potentials agree qualitatively with those measured by Klepeis and Rosa in a 1/2 x 3-inch generator channel. (Author)