Slanting of a Magnetically Stabilized Electric Arc in Transverse Supersonic Flow

Abstract

Experimental observations are presented which indicate the existence of a convective interaction mechanism affecting the direction and stability of electric current in a flowing gas. The observations were made of an electric arc confined in transverse supersonic flow by means of a nonuniform magnetic field mutually orthogonal with the freestream velocity field and the applied electric field. The positive column exhibits remarkable stability when allowed to slant across the applied electric field, approximately parallel to the freestream Mach line. The direction of slant is the Hall direction, cathode root downstream, but the magnitude of the slant angle does not appear to vary with the Hall parameter ωeτe. At the Mach numbers investigated, 2.0, 2.5, and 3.5, the inclination of the stable arc to the freestream is near the Mach angle, which is near the angle corresponding to a maximum in the discharge parameter E∥/Ps, the ratio of parallel component of electric field to pressure at the upstream boundary of the arc. Under conditions where the column could not assume its characteristic slant angle, a highly unstable discharge was observed.