Characterization of a low-power steady-state magnetoplasmadynamic device for non-propulsive applications

Abstract

The design, construction and operation of a low-power (5 - 15 kW) steady-state magnetoplasmadynamic (MPD) device is described. Its performance when operated on argon, nitrogen and oxygen-bearing gases is detailed, and typical operational data for runs with argon given, together with a current - voltage characteristic for the device. The electrode supports are water cooled; water temperature measurements show that thermal equilibrium is reached, thus enabling the anode and cathode power sinks to be determined and the device efficiency to be estimated. These figures are similar to those obtained from another device also operated in the tens of kilowatts power range. Electrode erosion and passivation mechanisms encountered in the device are described for the different propellants. Analysis of the cathode shows that the majority of the erosion occurs at the relatively cool cathode root and backplate. Passivation of the actively cooled anode due to deposited layers, when operated on oxygen-bearing gases, is discussed. Non-propulsive applications of such an MPD device for materials processing or for atomic oxygen production are discussed, together with proposed modifications to lengthen run times.