Measurements of the Equation of State of Deuterium at the Fluid Insulator-Metal Transition

Abstract

A high-intensity laser was used to shock-compress liquid deuterium to pressures from 22 to 340 gigapascals. In this regime deuterium is predicted to transform from an insulating molecular fluid to an atomic metallic fluid. Shock densities and pressures, determined by radiography, revealed an increase in compressibility near 100 gigapascals indicative of such a transition. Velocity interferometry measurements, obtained by reflecting a laser probe directly off the shock front in flight, demonstrated that deuterium shocked above 55 gigapascals has an electrical conductivity characteristic of a liquid metal and independently confirmed the radiography.

Inelastic X-Ray Scattering from Shocked Liquid Deuterium

“…The EOS of hydrogen for pressures <10 Mbar along the Hugoniot remains uncertain [15][16][17] where detailed validation of experimental techniques and numerical modeling is of utmost importance. While the present work has not obtained density measurements with accuracy below a few percent, it provides a needed alternative experimental platform where such validation could take place.…”

“…This research provides an experimental platform for the detailed study of compressed deuterium and is an important step toward measuring all the thermodynamic variables needed for EOS research, i.e., pressure (p), mass density (ρ), electron density (n e ), electron temperature (T e ), and ionization (Z), by combining inelastic x-ray scattering with shock velocity and optical pyrometry measurements [5,[15][16][17].…”

Novel diagnostic of low-Z shock compressed material

“…In principle this could be caused by two effects: (1) a rapid density jump causing proton density enhancement at the edge [18]; (2) an electric field at the edge of the slowly expanding plasma deflecting the protons outwards [19].…”

“…Inertial Confinement Fusion (ICF) success is also directly related to the understanding of shell pellet implosion and the final core compression. Both of these processes necessitate a precise knowledge of the microballoon material and the fuel (deuterium) EOS at very high pressures [2] (>100 GPa).…”

Time evolution of electron structure in femtosecond heated warm dense molybdenum

“…The data indicate a highly nonequilibrated state, 5 ps after heating. The study of Warm Dense Matter (WDM) shows a strong renewed interest, due to advances in transient techniques to create matter in this regime [1][2][3][4][5][6] , and in first principles calculations to simulate the physical properties 7,8 involved in various physical domains such as planetary physics 9 , inertial confinement fusion 10 , and applied laser processes 11 . The difficulty of modeling comes from the atomic level: disordered matter, partially degenerate electrons and strongly coupled ions.…”