A simple method for the determination of unreacted Hugoniots in inert and energetic materials

We recently reported the development of a 25mm diameter Modified Small-Scale Gap Test (MSSGT-25) from which we were able to obtain the standard go / no-go criterion, run distance, detonation velocity, and pressure using contact pins along the side of the test and Photon Doppler Velocimetry (PDV). Using a modified version of the gap test arrangement we have also been able to derive the unreacted Hugoniot for the test sample. A range of shock states (pressures) can be produced by varying the gap thickness in the MSSGT-25 test. By determining the shock velocity through the test sample and measurement of the particle velocity over a range of input shocks the unreacted Hugoniot can be determined. The input shock wave was provided by the MSSGT-25 booster/attenuator assembly and the test sample was a right-regular cylinder 10mm in length and 25mm diameter with 1.5mm hole drilled along its axis. This allowed one velocimeter probe to be directed on to the attenuator output face. The second probe was positioned adjacent to the first, directed onto the rear face of the specimen. This arrangement allowed the shockwave to impinge on both PDV channels in a near planar manner. The shock velocity in the sample was determined from difference in arrival times at the two PDV channels and the particle velocity from the free surface velocity measurement from rear of the sample. In this paper we report the results of a number of tests using the new technique.