Steady-state, controlled-discharge, linear nonequilibrium magnetogasdynamic generator.

Abstract

Experimental results are presented which demonstrate the basic feasibility of extracting steady electrical power from a plasma in a state of significant nonequilibrium ionization when flowing at high speed through a magnetic field. The work was carried out in a cesiumseeded argon blowdown facility at a stagnation temperature of 1500 °K, Mach numbers up to 0.6, and a magnetic field strength of 22,500 gauss. Each of the eleven channel electrode pairs was equipped with a discharge holder in the form of a small diameter ceramic tube between the electrodes. This device controlled the current path through beneficial interference by acting in a manner analogous to a simple flame holder, producing, especially at the generator entrance, a considerable improvement in both discharge steadiness and voltage efficiency. During uniform Faraday mode power extraction from the last seven electrode pairs the transverse electrical conductivity was approximately 150 times the corresponding thermal equilibrium value, and traversable probe readings showed that the induced Faraday electric field exceeded 90% of the theoretical value. It was concluded that pure magnetically induced ionization is impractical on account of the low ionization rate at temperatures up to 1500°K, and in the present experiment this problem was overcome by the expenditure of appreciable input preionization power through the first four electrode pairs.