Measurement of Quasi-Isentropic Compressibility of Gaseous Helium at a Pressure of ~10 TPa

A nonideal helium plasma has been compressed to a density of ~9 g/cm3 by a pressure of P ~ 10000 GPa produced by an explosive charge of 85 kg of TNT in a spherical two-cascade device. The experiment has been performed on an X ray setup using simultaneously three betatrons with a boundary energy of about 60 MeV and a multichannel optoelectronic system of recording X-ray images. The pressure of the compressed helium has been determined from the gas-dynamic calculation.