A Seed-Free Supersonic Non-Equilibrium MHD Generator with an RF-Power Assist Plasma-Initiation

Abstract

We describe a nonequilibrium seed-free pure-argon plasma working supersonic magnetohydrodynamic (MHD) power generation using a radiofrequency (rf ) electromagnetic filed to assist plasma initiation. The power generation experiment is conducted using a shock-tube driven disk-shaped generator. Since the tangential homogeneously is advantageous for the disk generator, the inductively coupling method is employed. The rf filed distributes in rather upstream of the generator. The constant rf-field power (13.56 MHz, 5 kW) is continuously supplied. Thermal equilibrium ionization due to an inlet stagnation temperature increase up to 4600 K does not offer practical power generation. In contrast, the unseeded plasma is pre-ionized by the small rf-power assist even at the low inlet stagnation temperature of 4000 K. The rf-power assist plasma-initiation contributes to the increase in electron temperature up to 8000 K and the continuous power generation, where the resulting electrical power output is 15 – 25 kW.