Isentropes and Hugoniot curves for dense hydrogen and deuterium

Equation-of-state measurement of dense plasmas heated with fast protons

Using an ultrafast pulse of mega-electron-volt energy protons accelerated from a laser-irradiated foil, we have heated solid density aluminum plasmas to temperatures in excess of 15 eV. By measuring the temperature and the expansion rate of the heated Al plasma simultaneously and with picosecond time resolution we have found the predictions of the SESAME Livermore equation-of-state (LEOS) tables to be accurate to within 18%, in this dense plasma regime, where there have been few previous experimental measurements.

Generalized x-ray scattering cross section from nonequilibrium plasmas

We propose a modified x-ray form factor that describes the scattering cross section in warm dense matter valid for both the plasma and the solid (crystalline) state. Our model accounts for the effect of lattice correlations on the electron-electron dynamic structure, as well as provides a smooth transition between the solid and the plasma scattering cross sections. In addition, we generalize the expression of the dynamic structure in the case of a two-temperature system (with different electron and ion temperatures). This work provides a unified description of the x-ray scattering processes in warm and dense matter, as the one encountered in inertial confinement fusion, laboratory astrophysics, material science, and high-energy density physics and it can be used to verify temperature relaxation mechanisms in such environments.

Evanescent high pressure during hypersonic cluster-surface impact characterized by the virial theorem

Matter under extreme conditions can be generated by a collision of a hypersonic cluster with a surface. The ultra-high-pressure interlude lasts only briefly from the impact until the cluster shatters. We discuss the theoretical characterization of the pressure using the virial theorem and develop a constrained molecular-dynamics procedure to compute it. The simulations show that for rare-gas clusters the pressures reach the megabar range. The contribution to the pressure from momentum transfer is comparable in magnitude and is of the same sign as that ("the internal pressure") due to repulsive interatomic forces. The scaling of the pressure with the reduced mechanical variables is derived and validated with reference to the simulations.

Reaction ensemble Monte Carlo technique and hypernetted chain approximation study of dense hydrogen

In spite of the simple structure of hydrogen, up to now there is no unified theoretical and experimental description of hydrogen at high pressures. Recent results of Z-pinch experiments show a large deviation from those obtained by laser driven ones. Theoretical investigations including ab initio computer simulations show considerable differences at such extreme conditions from each other and from experimental values. We apply the reaction ensemble Monte Carlo technique on one hand and a combination of the hypernetted chain approximation with the mass action law on the other to study the behavior of dense hydrogen at such conditions. The agreement between both methods for the equation of state and for the Hugoniot curve is excellent. Comparison to other methods and experimental results is also performed.