Kerr Cell Photography of High Speed Phenomena

Abstract

Visible light photographs have been obtained of metal jets squirted from the lined conical cavities of high explosive charges. Since these jets travel through air at nearly meteoric velocities (7 to 12×105 cm/sec), their front ends are heated to incandescense and vaporized. The remainder of the jet is relatively nonluminous and is photographed by synchronizing a Kerr cell shutter (exposure time <1 μsec) and an exploding wire light source (peak intensity 4×108 candlepower) with the phenomenon. Schlieren type photography cannot be used because of the luminosity accompanying the phenomenon. Detail is obtained in the photographs by using a large lens with a seven-in. focal length. To maintain the effective aperture at f/4 requires a large Kerr cell which in turn requires a 25,000 volt pulse for its operation. The technique is used in studying the action of these jets on steel, water, glass, and Plexiglas. The technique is also used in studying the propagation of shock waves in solids and liquids when these phenomena are due to the action of the metal jets or to the more direct action of explosives.