Compressibility of Nonideal Deuterium and Helium Plasmas up to 20 TPa

We present our experimental results on the compressibility of strongly coupled (nonideal) degenerate deuterium and helium plasmas quasi-isentropically compressed to pressures P ~ 20 TPa in devices with a spherical geometry. The trajectories of the plasma-compressing metallic shells were recorded with the help of powerful pulsed X-ray sources (betatrons) with a boundary electron energy of 60 MeV. A high-current accelerator with a penetrability of objects with an equivalent thickness of 250-mm of lead has been used for the first time as an X-ray source in our experiments. Plasma densities up to ρ ≈ 14 g cm –3 were determined from the measured radius of the shell at the instant of its “stopping.” We derived the compressed-plasma pressure based on our gasdynamic computations including the real characteristics of the experimental devices.