Shock compression of statically precompressed low-Z materials*

For advancing our understanding of the formation, evolution, and interior structure of icy planets (e.g. Uranus and Neptune), we performed accurate experimental measurements of the thermodynamic, optical, and transport properties and chemical bonds of low-Z systems and their mixtures at extreme conditions. To recreate the planetary conditions, static precompression with diamond anvil cells (DACs) is coupled to dynamic compression at laser facilities (Omega, NIF). We studied the shock pressure-density relation of precompressed nitrogen, revealing a gradual evolution in chemical bond; the dissociation of initial molecular nitrogen and L-shell ionization of dissociated atomic nitrogen. We also explored the shock pressure-density-temperature relation and optical property of water and water-based mixtures. Further, we have been developing a new DAC platform on NIF to explore unprecedented extreme conditions. With help from advanced quantum simulations, these results provide a more complete picture of the interior structure of giant planets and strong benchmark for future theoretical developments.