LDRD ER Final Report: Recreating Planetary Cores in the Laboratory: New Techniques to Extremely High Density States
An accurate equation of state (EOS) for planetary constituents at extreme conditions is the key to any credible model of planets or low mass stars. However, very few materials have their high pressure (>few Mbar) EOS experimentally validated, and even then, only on the principal Hugoniot. For planetary and stellar interiors, compression occurs from gravitational force so that material states follow a line of isotropic compression (ignoring phase separation) to ultra-high densities. An example of the hydrogen phase space composing Jupiter and one particular Brown Dwarf is shown. At extreme densities, material states are predicted to have quite unearthly properties such as high temperature superconductivity and low temperature fusion. High density experiments on Earth are achieved with either static compression techniques (i.e. diamond anvil cells) or dynamic compression techniques using large laser facilities, gas guns, or explosives. The ultimate goal of this multi-directorate and multi-institutional proposal was to develop techniques that will enable us to understand material states that previously only existed at the core of giant planets, stars, or speculative theories. Our effort was a complete success, meeting all of the objectives set out in our proposals. First we focused on developing accurate Hugoniot techniques to be used for constraining the equation of state at high pressure/temperature. We mapped out an accurate water EOS and measured that the ionic->electronic conduction transition occurs at lower pressures than models predict. These data and their impact are fully described in the first enclosed paper ''The Equation of State and Optical Properties of Water Compressed by Strong Shock Waves.'' Currently models used to construct planetary isentropes are constrained by only the planet radius, outer atmospheric spectroscopy, and space probe gravitational moment and magnetic field data. Thus these data, which provide rigid constraints to these models, will have a significant impact on a broad community of planetary and condensed matter scientists, as well as our fundamental understanding of the giant planets. We then developed and tested precompressed and multiple shock techniques on water. Scientists around the world have teamed with us to conduct these complex and seminal high density experiments which allow access to the extreme core states of giant plants. Double shock experiments using a variety of anvils to compress water to densities higher and temperatures lower than accessible by single shock Hugoniot techniques. First a clear determination of the EOS and optical properties of the anvils needed to be measured. These properties for LiF and A1203 are written up in the second attached article, ''Shock-Induced Transformation of Sapphire and Lithium Fluoride into Semiconducting Liquids.'' An example double shock data record for water is shown. This data is being written up for publication.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15003387
- Report Number(s):
- UCRL-ID-151388; TRN: US0407008
- Resource Relation:
- Other Information: PBD: 7 Feb 2003
- Country of Publication:
- United States
- Language:
- English
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