Using high energy density facilities to explore matter from a few kilobar to several gigabar

Gilbert W. Collins, Lawrence Livermore National Laboratory

A new generation of materials experiments at high pressures-densities-temperatures is now possible due to a variety of high energy density (HED) facilities and new compression techniques. These facilities will be used over the next decade to measure equation of state and transport properties of materials at gigabar pressure and over 10-fold compression. I will describe recent shock wave and shockless compression experiments using HED facilities to give a flavor of our progress over the past couple of years. Recent shock compression experiments have measured the insulator-conductor transition and the high pressure equation of state of several low Z materials (C, H2), SiO2, H2, He) from Kbar to 10s of Mbar. For both He and H2 the initial density was varied by a factor of 3 with precompression using diamond anvil cell targets. The insulator-conductor transition is sometimes coincident with melting (diamond), a change in chemistry (i.e. SiO2) or thermal activation of carriers across a band gap (H2O). Shockless compression experiments are being used to explore "low temperature and high pressure" multi-phase diagrams and phase transition kinetics with loading rates ranging from 106 to 108 s-1. I will describe how we plan to extend these new techniques on HED facilities over the next decade.

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