Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session O4: Equation of State III |
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Chair: Sarah Stewart, University of California, Davis Room: Regency Ballroom A |
Wednesday, July 12, 2017 9:15AM - 9:45AM |
O4.00001: Experimental Discovery of Superionic Water with Dynamic Compression. Invited Speaker: Marius Millot The pressure-temperature phase diagram of water exhibits a striking degree of polymorphism with more than 15 polymorphs of molecular ice and the pressure-induced transition to the ionic ice X near 70 GPa. Upon further compression and at elevated temperature, several molecular dynamics studies have predicted that water becomes superionic, an extraordinary state with liquid-like hydrogen ions diffusing within a solid lattice of oxygen. We will report experimental evidence for superionic electrical conductivity above 100 GPa and 2000 K using velocimetry, pyrometry and optical property measurements of shock compressed $H_2O$ ice VII. We will also present in-situ x-ray diffraction of ice up to 4 Mbar using reverberation compression showing that the superionic conduction indeed exists in the presence of a solid oxygen lattice as predicted three decades ago. The new XRD data also suggest the discovery of a new solid ice phase having a face-centered-cubic oxygen lattice. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-724285. [Preview Abstract] |
Wednesday, July 12, 2017 9:45AM - 10:00AM |
O4.00002: Laser shock compression experiments on precompressed water in ``SG-II'' laser facility. Hua Shu, Xiuguang Huang, Junjian Ye, Sizu Fu Laser shock compression experiments on precompressed samples offer the possibility to obtain new hugoniot data over a significantly broader range of density-temperature phase than was previously achievable. This technique was developed in ``SG-II'' laser facility. Hugoniot data were obtained for water in 300 GPa pressure range by laser-driven shock compression of samples statically precompressed in diamond-anvil cells. [Preview Abstract] |
Wednesday, July 12, 2017 10:00AM - 10:15AM |
O4.00003: Complete Equation of State for Shocked Liquid Nitrogen: Analytical Developments J. M. Winey, Y. M. Gupta The thermodynamic response of liquid nitrogen has been studied extensively, in part, due to the long-standing interest in the high pressure and high temperature dissociation of shocked molecular nitrogen. Previous equation of state (EOS) developments regarding shocked liquid nitrogen have focused mainly on the use of intermolecular pair potentials in atomistic calculations. We present EOS developments for undissociated liquid nitrogen, incorporating analytical models, for use in shock wave continuum calculations. The analytical models, together with Hugoniot data, were used to extrapolate a low pressure reference EOS for nitrogen [Span, et al., J. Phys. Chem. Ref. Data 29, 1361 (2000)] to high pressures and high temperatures. Using our EOS, the calculated pressures and temperatures for single shock, double shock, and multiple shock compression of liquid nitrogen provide a good match to the measured results over a broad range of P-T space. These calculations provide the first comparison of EOS developments with recently-measured P-T states under multiple shock compression [Lacina and Gupta, J. Chem. Phys. 141, 084503 (2014)]. The present EOS developments are general and are expected to be useful for other liquids that have low pressure EOS information available. [Preview Abstract] |
Wednesday, July 12, 2017 10:15AM - 10:30AM |
O4.00004: Evaluating the equation-of-state models of nitrogen in the dissociation regime: an experimental effort Jiangtao Li, Qifeng Chen, Zhijian Fu, Yunjun Gu, Jun Zheng, Chengjun Li A number of experiments were designed so that pre-compressed nitrogen (~20 MPa) was shock-compressed reverberatively into a regime where molecular dissociation is expected to influence significantly the equation-of-state and transport properties. The equation of state of nitrogen after each compression process was probed by a joint diagnostics of multichannel optical pyrometer (MCOP) and Doppler pin system (DPS). The equation of state data thereby obtained span a pressure-density range of about 0.02-130 GPa and 0.22-5.9 g/cc. Furthermore, based on the uncertainties of the measurements, a Monte Carlo method was employed to evaluate the probability distribution of the thermodynamic state after each compression. According to Monte Carlo results, a number of equation-of-state models or calculations for nitrogen in the dissociation regime were assessed. [Preview Abstract] |
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