High Pressure Hugoniot Measurements Using Converging Shocks

Abstract

Plate impact experiments are a powerful tool in equation of state development, but are inherently limited by the range of impact velocities accessible to the gun. In an effort to dramatically increase the range of pressures which can be studied with available impact velocities, a new experimental technique is being developed. The possibility of using converging shock waves to produce a high pressure Mach reflection is examined. The technique proposed uses a composite target simply consisting of two concentric cylinders, with the only requirement being the initial shock speed in the outer cylinder is greater than that in the inner cylinder. Conically converging shocks will be generated at the interface due to the impedance mismatch and axisymmetric geometry of the composite target. Upon convergence, an irregular reflection must occur, at which point the conical analog of a Mach reflection develops. Once the Mach reflection reaches a steady state, the high pressure state in the Mach disk can be measured using velocity interferometry and impedance matching techniques. Experimental results on a copper inner cylinder are in good agreement with numerical simulations and data in the literature.