Recreating the Deep Interior Conditions of Gas Giants in the Laboratory: Phase Separation in Hydrogen-Helium Mixtures at Jovian Planet Conditions

Abstract:

Several new techniques are being developed and used to benchmark equation of state and transport theories implicit to gas giant planet evolution models. We will discuss two particular experiment campaigns; one set of experiments exploring the nature of H and He mixtures in the deep interiors of Jupiter and Saturn, and a second set of experiments exploring the nature of matter at multi-gigabar pressures. Whether or not H-He mixtures phase separate in Jovian planets is important to our understanding of the structure and evolution of Jupiter and Saturn.  Also integral to such planet models, as well as mechanisms for H-He phase separation, are the insulating-to-conducting and the molecular-to-atomic-hydrogen transitions in the H-He mixture. Coupling static and dynamic compression techniques has allowed us to make the first thermodynamic and transport measurements of H-He mixtures at deep Jovian planet conditions. These data provide evidence that the H-He fluid demixes at the high pressures and temperatures expected to exist deep inside Saturn and Jupiter. The second set of experiments explored how matter behaves at 10’s of billions of atmospheres pressure, well beyond the atomic unit of pressure required to distort core electron orbitals of mid-Z atoms. To achieve these conditions in the laboratory a new series of convergent shock techniques was developed. We present the first temperature-density and pressure data for this regime.