155 / 2023-04-14 22:28:04

Adiabatic Sound Speed of Shock-Compressed Liquid Deuterium up to 800 GPa

deuterium, sound speed, shock wave

高压物理与材料科学 > 动高压-I

Hydrogen, the most abundant element in the universe, is of fundamental importance for astrophysics and technological applications such as inertial confinement fusion (ICF) [1]. The adiabatic sound speed c_s derivative from EOS is a more sensitive and crucial variable to verify existing theories since the sound speed behind a shock front in fluids defines the local slope of the isentrope along the shock states in the pressure-density frame as . In this work, we report the laser-driven experiments of adiabatic sound speed measurements on the ShenGuang (SG) series 100-kilojoule laser facility at Laser Fusion Research Center (LFRC) for shock-compressed liquid deuterium at a broad pressure range of 200 < P < 800 GPa, providing the highest-pressure data to date for constraining theoretical models. The existing EOS models obviously overestimate the sound speed than the experimental data at pressures between 200 to 350 GPa, although data beyond 350 GPa are in agreement. The experimental results are consistent with our modified direct path-integral Monte Carlo (M-DPIMC) simulations, which demonstrate that atomic ionization is quite essential for the accurate prediction of sound speed in the partial ionization regime. This work is of significant importance for the development of the high-pressure response properties of hydrogen’s isotopes, directly related to inertial confinement fusion and astrophysics.