Phase transition in a strongly nonideal deuterium plasma generated by quasi-isentropical compression at megabar pressures

High-explosive driven generators of cylindrical and plane shock waves in D-2 and H-2 were used for the generation of warm and dense strongly nonideal matter with an intense interparticle interaction and Fermi statistics. Highly resolved flash x-ray diagnostics were used to measure the adiabatic plasma compressibility. The thermodynamic measurements demonstrated the 20% increase of density at megabar pressure, just in the density range, where the electrical measurements indicated a sharp - 5 orders of magnitude - increase of electrical conductivity due to pressure ionization in strongly coupled plasmas.