Experiments on Quasi-Isentropic Compression of Deuterium and Helium to Extreme Pressures of ≈3000 GPa

Experiments were performed to study the spherical compression of deuterium and helium to pressures of ≈3000 GPa in a quasi-isentropic regime. The process was recorded by a multiframe radiographic system which produces up to nine x-ray images of a cavity with gas at different times in one experiment. X-ray images show that explosive devices provide a nearly spherically symmetric shape of the cavity with gas up to the maximum compression of the gas. The experimental data are in good agreement with the results of calculations using the equations of state of the gases studied. From the results of these calculations, the parameters of the region of the compressed gas states obtained in the experiments were determined: for deuterium, a density of 5.5 g/cm3 and a pressure of 3.6 TPa; for helium, a density of 4.7 g/cm3 and a pressure of 2.4 TPa.