Deformation of Shock Wave in Supersonic Plasma Jet Caused by Applied Magnetic Field

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An experimental study of underexpanded plasma jet was carried out to reveal the effects of applied magnetic field on flow behavior around the normal shock wave, that is, Mach disk. Photographic images of the flow were taken with a digital single-lens reflex camera. The light intensity is extracted from uncompressed RAW files of the images. Angles of barrel and reflected shock wave to the flow direction at the reflected shock starting point were determined from the gradient of the light intensity. The angle of reflected shock wave increases with magnetic field intensity. On the other hand, the angle of barrel shock wave tends to decrease with increases in the field strength. Contour plots of the light intensity in downstream region from Mach disk significantly changes with applied magnetic field compared to those without the field. The effects of magnetic field on oblique shock wave around a conical probe in supersonic region of the jet were also studied using the light intensity . The local Mach number in the jet, evaluated from the oblique shock angle using Taylor-Maccoll equation, shows a tendency to increase with the field strength.