Equations of State of Matter at High Energy Densities

Abstract

Abstract:The physical properties of hot dense matter over a broad domain of the phase diagram are of interest in astrophysics, planetary physics, power engineering, controlled thermonuclear fusion, impulse technologies, enginery, and other applications. The present report reviews the contribution of modern experimental methods and theories to the problem of the equation of state (EOS) at extreme conditions. Experimental techniques for high pressures and high energy density cumulation, the drivers of intense shock waves, and methods for the fast diagnostics of high-energy matter are considered. It is pointed out that the available high pressure and temperature information covers a broad range of the phase diagram, but only irregularly and, as a rule, is not thermodynamically complete; its generalization can be done only in the form of a thermodynamically complete EOS. As a practical example, construction of multi-phase EOS for tungsten is presented. The model's results are shown for numerous shock-wave data, the high-pressure melting and evaporation regions and the critical point of tungsten.

Experimental and Theoretical Determination of the Effective Penetration Depth of Ultrafast Laser Radiation in Stainless Steel

“…The tensile stress of the rarefaction wave transforms the stable liquid into a metastable liquid, in which the binodal is crossed, and cavitation below the surface is induced if the time under negative pressure exceeds the time for forming a stable bubble. As a result, the spallation Schematic temperature-density-pressure and phase diagram according to [33][34][35][36][37][38][39] including four typical trajectories of a point slightly below the surface for spallation: white and light purple, and for phase explosion: purple and dark purple. The darker the color of the trajectory, the higher the fluence of the laser radiation.…”

Ab initio calculations of the thermodynamic parameters of lithium, sodium, and potassium oxides under pressure

“…The thermodynamic poten tial of the free energy is most suitable for the descrip tion of the system. Knowing the free energy of a homogeneous system under the conditions of thermo dynamic equilibrium, we can determine the partial derivatives of the free energy, which, in turn, allow us to obtain the other thermodynamic functions [23,24].…”

Approaching the “cold curve” in laser-driven shock wave experiment of a matter precompressed by a partially perforated diamond anvil

“…To be able to describe such physical events at a verity of different conditions, the entire pressure-temperature-volume range between the cold isotherm and principal Hugoniot must be considered. In the past, static and dynamic conditions of materials were extensively studied using diamond anvil cells (DACs) (Hemley, 2010) and shock wave techniques (Fortov & Lomonosov, 2010), respectively. DAC's static high pressure experiments usually follows an isotherm at room temperature and are limited to pressures of up to about 5 Mbar (Popov, 2010), when combined with laser heating techniques, the temperature can reach up to about 4000 K (Errandonea, 2006).…”

“…DAC's static high pressure experiments usually follows an isotherm at room temperature and are limited to pressures of up to about 5 Mbar (Popov, 2010), when combined with laser heating techniques, the temperature can reach up to about 4000 K (Errandonea, 2006). Dynamic shock measurements using gas gun facilities are limited to pressures of up to about 10 Mbar, while laser driven shocks can reach up to about 1000 Mbar (Fortov & Lomonosov, 2010), both techniques are constrained to the principal Hugoniot curve. In shock wave experiments, it is not possible to control the temperature independently from the shock pressure; also, the compression is limited since above a certain value most of the shock energy is converted to heating the sample instead of compressing it.…”