Generating extreme densities in water using laser-driven shocks in diamond anvil cells

Laser-driven shock waves can generate very high-pressure conditions at high temperatures; in contrast, diamond anvil cells (DAC) are uniquely suited to producing high pressures at low temperatures. We describe experiments that combine these two techniques in order to produce extremely high-density states of water, off the principal Hugoniot. Water was initially compressed in a DAC up to ~ 10 kbar. The DAC was then irradiated using the Vulcan laser at Rutherford-Appleton Laboratory. The pressure and density of the water and reflectivity of the water shock front were determined using a VISAR technique while temperatures were determined using optical pyrometry.