EXPERIMENTAL STUDY OF THE HALL VOLTAGE IN A LARGE HALL PARAMETER LINEAR MHD GENERATOR.

Experiments were performed to isolate the primary causes of the Hall voltage reduction in large Hall parameter, linear MHD generators. The MHD generator working fluid was either shock heated Xenon or a shock heated 9.2 carbon monoxide - 90.8 Xenon gas mixture. The Hall parameter values in the generator ranged from 1 to 10. The transverse current level per electrode was varied from 10 amperes at which Lorentz force and non-equilibrium effects were negligible to 40 amperes at which both effects were appreciable. At all current levels, optical observations showed that the current in the generator is concentrated in streamers. However, at the lower current levels it was possible to obtain reasonably good agreement with a uniform non-equilibrium plasma, MHD generator theory. At higher current levels the experimental Hall voltage was below the value predicted by this theory. The deviation increased with increasing Lorentz force. It was optically observed that non-uniform electrode conduction sharply increased the current density and hence the Lorentz force near the electrodes. Thus it is concluded that in the present experiments the Lorentz force is a primary factor in reducing the Hall voltage. Author