Reflectivity of Shock Compressed Xenon Plasma

Equation of state for shock compressed xenon in the ionization regime: ab initio study

Quantum molecular dynamic (QMD) simulations have been applied to study the thermophysical properties of liquid xenon under dynamic compressions. The equation of state (EOS) obtained from QMD calculations are corrected according to Saha equation, and contributions from atomic ionization, which are of predominance in determining the EOS at high temperature and pressure, are considered. For the pressures below 160 GPa, the necessity in accounting for the atomic ionization has been demonstrated by the Hugoniot curve, which shows excellent agreement with previous experimental measurements, and thre…

Reflectivity and Exact Asymptotic Forms of the Dielectric Function of Non-Ideal Plasmas

The problem of calculation of the reflectivity of non-ideal shock-compressed plasmas is revisited. The dielectric formalism based on the method of moments incorporating exact asymptotic forms and sum rules is applied to the new experimental data. The approach is based on the Ansatz of reflection of laser radiation from a thin shock-front and possesses one adjustable parameter which depends only on the thermodynamic conditions of the experiment. A self-consistent agreement with all available experimental data is achieved.

Explosive shock tube of xenon non-ideal plasma for proton radiography

A high explosive shock tube of non-ideal gaseous plasma for proton radiography is described. The gas dynamic flow in the shock compressed xenon at initial pressure of 7 bar was investigated in the tube. The velocity of the shock wave in xenon and the associated particle velocity were measured by a high-speed rotating mirror streak camera. Experimental time-distance data was used for approximation of the velocities by exponential decay functions. The shock tube is intended for generation of non-ideal plasma of xenon at the pressure of 5-12 kbar, the density of 0.24-0.3 g/cm3 when the initial pr…

Thermophysical properties for shock compressed polystyrene

We have performed quantum molecular dynamic simulations for warm dense polystyrene at high pressures. The principal Hugoniot up to 790 GPa is derived from wide range equation of states, where contributions from atomic ionizations are semiclassically determined. The optical conductivity is calculated via the Kubo-Greenwood formula, from which the dc electrical conductivity and optical reflectivity are determined. The nonmetal-to-metal transition is identified by gradual decomposition of the polymer. Our results show good agreement with recent high precision laser-driven experiments.

Characterising equation of state and optical properties of dynamically pre-compressed materials

Characterising materials at pressures of several megabar and temperatures of a few thousand Kelvin is critical for the understanding of the Warm Dense Matter regime and to improve planetary models as these conditions are typical of planets' interiors. Today, laser-driven shock compression is the only technique to achieve multimegabar pressures, but the associated temperatures are too high to be representative of planetary states. Double-shock compression represents an alternative to explore lower temperatures. Here we present a method to create well-controlled double-shocked states and measure…

压缩超快摄影揭示稠密气体激光击穿形成的等离子体在早期演化中内部过程占主导地位

Compressed Ultrafast Photography of Plasmas Formed from Laser Breakdown of Dense Gases Reveals that Internal Processes Dominate Evolution at Early Times

本文利用压缩超快摄影研究高压气体激光击穿等离子体的早期演化，发现其收缩而非膨胀，且内部输运主导冷却过程，为研究稠密等离子体状态方程和流体动力学提供了理想体系。