Role of plasma science in the studies of planetary fluids

Summary form only given, as follows. Summary form only given. Accurate phase diagrams for simple molecular fluids (H/sub 2/, H/sub 2/O, NH/sub 3/ and CH/sub 4/) and their constituent elements at temperatures of several thousand Kelvin and pressures of several Mbar are integral to planetary models of the gas giant planets ( Jupiter, Saturn, Uranus and Neptune). Experimental data at high pressure has, until recently, been linuted to around 1 Mbar with both dynamic (ie. two-stage light-gas guns) and static (ie. diamond anvil cells) techniques. Current high intensity laser facilities can now produce tens of Mbar pressures in these light fluids, reaching the dense plasma states required for understanding the cores of giant planets and low mass stars. This presentation will first describe recent Hugoniot data for water at pressures up to 8 Mbar and carbon up to 30 Mbar At Hugoniot pressures near 1 Mbar, water transitions from an ionic to electronic conductor as observed from the shock front reflectivity. Pressure-densitytemperature data follow the Sesame database up to 8 Mbar where water is a dense plasma. Carbon starting from the chamond phase is shown to metallizes at Hugoniot pressures extending from 6 to 11 Mbar.