Thin foil acceleration method for measuring the unloading isentropes of shock-compressed matter

The thin foil acceleration method was tested in explosively-driven experiments with shock compressed PMMA and polyethylene at shock pressures up to 35 GPa. A transition was observed from the behavior expected for condensed matter to the gas-like response of the PMMA samples. Measurements of the PMMA unloading isentrope have been completed by modification of the equation of state in the vaporization region.