Quasi-Isentropic Compression of Gaseous Helium and Deuterium in Spherical Structures at Terapascal Pressures

The results of four experiments on studying preliminarily statically compressed gaseous helium and deuterium during their subsequent compression in explosive spherical cascade structures providing quasi-isentropic gas compression are presented. For helium, the following parameters were achieved: in one experiment, the compression pressure is P mean ≈ 4.9 TPa at a density ρ max ≈ 6.4 g/cm 3 and the compression ratio is δ = ρ/ρ 0 ≈ 320; in another experiment, P mean ≈ 10.9 TPa, ρ max ≈ 10.3 g/cm 3 , and δ ≈ 470. For deuterium, these parameters are P mean ≈ 3.4 TPa, ρ max ≈ 6.0 g/cm 3 , and δ ≈ 162 in one experiment and P mean ≈ 13.3 TPa, ρ max ≈ 11.4 g/cm 3 , and δ ≈ 520 in another experiment. The gas density was determined by an X-ray method using the position of the boundaries of the steel shells compressing a gas. The experiments are simulated with a one-dimensional gasdynamic software package, in which the Kopyshev–Khrustalev equations of state are used for the gases under study. The pressures are determined using calculations, in which the dynamics of gas compression is satisfactorily simulated for the entire set of experiments.