High Accuracy Isentropic Compression Studies with High Explosive Pulsed Power

Summary form only given. An extensive study of the one-dimensional isentropic compression experiment (ICE), performed with High Explosive Pulsed Power (HEPP), has been completed. The study has demonstrated that accurate, high pressure, isentropic equations of state (EOS) data may be obtained with this technique. The physics of electromagnetic loading in the ICE technique is presented. It is shown that the HEPP-ICE load configuration is capable of producing magnetic pressures that are uniform to 1 part in 1000 over the central 87% of the sample faces, and that HEPP-ICE provides exact matching of the pressures between opposing samples. This magnetic uniformity and matching are necessary for the highest accuracy isentropic EOS data. Isentropic EOS data have been obtained with a prototype HEPP-ICE system, and the results for tungsten and copper demonstrate the inaccuracy of the technique, which may be as low as 0.2% in pressure. Moreover, some interesting structure was observed in the elastic to plastic failure of tungsten, and this differs from published shock data. It is shown that a large-scale HEPP-ICE system (now being designed) is capable of producing shock-free loading up to 2.2 TPa in 10-mm thick tungsten samples. The study also shows that HEPP-ICE is well suited to the production of high accuracy, high-pressure, shock-free EOS data because of the long risetime currents that can be attained with it; risetimes in excess of 2 mus are possible in comparison to 500 ns on other machines.