Hydrogen and deuterium in shock wave experiments, ab initio simulations and chemical picture modeling

Abstract

Abstract. We present equation of state data of shock compressed hydrogen and deuterium. These have been calculated in the physical picture by using ab initio molecular dynamics simulations based on finite temperature density functional theory as well as in the chemical picture via the Saha-D model. The results are compared in detail with data of shock wave experiments obtained for condensed and gaseous precompressed hydrogen and deuterium targets in a wide range of shock compressions from low pressures up to megabars.

Thermodynamic Properties of Hydrogen Plasma to Megabars

“…Note that the Hugoniots are sensitive especially to the caloric EOS [31,34]. Such comparison was made in [2,31] and it exposed there satisfactory agreement of the data on all deuterium Hugoniots with the predictions of the SAHA-D EOS . This comparison has no information on temperature behaviour of shock compressed deuterium along adiabatic path.…”

“…Fig. 2 Compressibility factor of hydrogen plasma at density 10 −3 g/cm 3 : SCVH -well known approximation based on chemical picture [12], OPAL - [27] with ground state energy of hydrogen atom corrected in [25], DPIMC - [26], rigorous physical model - [25], the SAHA-S - [18], the SAHA-D - [1,2]. Approximate values of dissociation and ionization degree are notified on the right axis.…”

“…8 Compressibility factor of deuterium plasma on the Hugoniot ρ0 = 0.17 g/cm 3 . Comparison of experimental data Bailey et al [32], Brigoo et al [33] and the theoretical approaces SCVH - [12], DPIMC - [26], RPIMC - [7], DFT-MD - [2] and the SAHA-D [1, 2] -the current work.…”

“…Soft spheres approximation (SS) [21] modified for mixture of particles of different radii is used. In this case the effective packing fraction is calculated [2,13] through the individual diameters σ j = 2r j of particles in correspondence with one-fluid approximation.…”

“…There are a lot of experimental and theoretical investigations of the behaviour of hydrogen and its isotopes in a wide range of pressures and temperatures. Experimental investigations of shock and isentropically compressed hydrogen have a rather long history (See, for instance [1,2] and references therein). The essential part of experimental information consisting of results of shock-wave and quasi-isentropic compression is characterized by partial dissociation and ionization.…”