Magnetic field and electrode geometry effects on vehicle discharging by neutral gas release

Abstract

In earlier work we quantified the effect of the Mach number of neutral gas release and neutral gas species on minimum breakdown potential in ionospheric‐like plasmas. The theoretical basis of this work incorporates the Townsend breakdown criterion to the ambient plasma to characterize the discharge. The results of a model based on this theory provide good agreement with the results of experiments in a variety of gases performed in the large Space Physics Simulation Chamber (SPSC) at the Naval Research Laboratory. The experiments in the SPSC used a 10 cm × 10 cm aluminum cylinder which contained a neutral gas release valve and variable Mach number nozzles. The cylinder was charged to high negative potential before neutral gas was released, causing breakdown to the ambient plasma for sufficient valve plenum pressure. We have recently incorporated both electrode geometry design changes and an external magnetic field produced by a permanent magnet in an effort to lower the breakdown voltage required. We have preliminary results which suggest that both an extended smaller cylinder and an external magnetic field can significantly lower the potentials required for breakdown. We are in the process of verifying these results by adding an adjustable constant magnetic field both perpendicular and parallel to the gas release direction.