Shock compression of liquid helium to 360 GPa

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Abstract
Data for the shock equation of state of helium are obtained up to 360 G Pa , nearly doubling the pressure of previous experimental measurements. The helium samples are first precompressed to 0.35–0.42 g c m − 3 in a diamond anvil cell prior to laser-driven shock compression at the Omega Laser Facility. Time-resolved Doppler velocimetry and pyrometry reveal significant reflectivity and greater compressibility compared to the predictions of existing broad-range tabular equation of state models, which may be caused by the onset of ionization. These experimental observations, however, are largely captured with molecular-dynamics simulations based on density functional theory, affirming the ability of first-principles techniques to capture complex physics, while enabling critical insight for the behavior of warm dense helium in Jovian interiors and white dwarf atmospheres.
Funding Information
  • Lawrence Livermore National Laboratory (B632749)
  • Lawrence Livermore National Laboratory (DE-AC52-07NA27344)
  • U.S. Department of Energy (DE-NA0004146)
  • U.S. Department of Energy (De-NA0003960)
  • U.S. Department of Energy (DE-NA0004147)
  • Laboratory Directed Research and Development (19-ERD-031)
  • National Science Foundation (PHY2020249)
  • Fusion Energy Sciences (DESC0020340)
  • Fusion Energy Sciences (DESC0023341)

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