Publications

The noble gas xenon is a particularly interesting element. At standard pressure xenon is an fcc solid which melts at 161 K and then boils at 165 K, thus displaying a rather narrow liquid range on the phase diagram. On the other hand, under pressure the melting point is significantly higher: 3000 K at 30 GPa. Under shock compression, electronic excitations become important at 40 GPa. Finally, xenon forms stable molecules with fluorine (XeF{sub 2}) suggesting that the electronic structure is significantly more complex than expected for a noble gas. With these reasons in mind, we studied the xenon Hugoniot using DFT/QMD and validated the simulations with multi-Mbar shock compression experiments. The results show that existing equation of state models lack fidelity and so we developed a wide-range free-energy based equation of state using experimental data and results from first-principles simulations.

Shock and shockless compression methods were used to examine the loading path and rate dependence of single crystal x-cut quartz. Analysis of the transmitted wave profiles show remarkably different behavior between shock and shockless loaded samples. Shock loaded x-cut quartz shows inelastic deformation below 5 GPa. Ramp loaded samples do not show inelastic behavior until approximately 9 GPa, with the onset of this behavior dependent on sample thickness. The results demonstrate that both loading path and rate play important roles in the inelastic behavior of materials. © 2009 American Institute of Physics.

Abstract not provided.

Abstract not provided.