Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session V6: Equation of State IV |
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Chair: Scott Crockett, Los Alamos National Laboratory Room: Grand Ballroom VI |
Thursday, June 30, 2011 4:00PM - 4:30PM |
V6.00001: A New Wide-Range Equation of State for Xenon Invited Speaker: We describe the development of a new wide-range equation of state (EOS) for xenon. Three different prior EOS models predicted significant variations in behavior along the high pressure Hugoniot from an initial liquid state at 163.5 K and 2.97 g/cm$^3$, which is near the triple point. Experimental measurements on Sandia's Z machine as well as density functional theory based molecular dynamics calculations both invalidate the prior EOS models in the pressure range from 200 to 840 GPa [1]. The reason behind these EOS model disagreements is found to lie in the contribution from the thermal electronic models. A new EOS [2], based upon the standard separation of the Helmholtz free energy into ionic and electronic components, is constructed by combining the successful parts of prior models with a semi-empirical electronic model. Both the fluid and fcc solid phases are combined in a wide-range, multi-phase table. The new EOS is tabulated on a fine temperature and density grid, to preserve phase boundary information, and is available as table number 5191 in the LANL SESAME database [3]. Improvements over prior EOS models are found not only along the Hugoniot, but also along the melting curve and in the region of the liquid-vapor critical point. \\[4pt] {*}Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.\\[4pt] {[1]} S. Root et. al., Physical Review Letters 105, 085501 (2010).\\ {[2]} J. H. Carpenter et. al., EPJ Web of Conferences 10, 00018 (2010).\\ {[3]} http://t1web.lanl.gov/ [Preview Abstract] |
Thursday, June 30, 2011 4:30PM - 4:45PM |
V6.00002: Properties of dense xenon plasma under double--shock compression to 180 GPa Jun Zheng Warm dense plasmas having uniform, constant density, and temperature were generated by passage of planar shock wave through gas. The pressure of the Xe plasma was accurately measured by optical radiation method under double--shock compression to 180 GPa. The shock was produced using the flyer plate impact by accelerated up to $\sim $6 km/s with a two--stage light gas gun. The time-resolved optical radiation histories were acquired by using a multi--wavelength channel optical transience radiance pyrometer. Shock velocity was measured and particle velocity was determined by the impedance--matching methods. The equation of state of dense xenon plasma are calculated using the self--consistent fluid variational theory along the Hugoniot curve and compared with present experimental results over a wide range of pressures and temperatures. The observed shock compression ratios range from Ru/Ru0=3.7 for Ru0=2.2 g/cm$^{3}$ to Ru/Ru0=8.5 for Ru0=0.04 g/cm$^{3}$. The comparison of the Hugoniots in the Pressure-compression plane clearly shows how higher initial densities result in lower final compression. [Preview Abstract] |
Thursday, June 30, 2011 4:45PM - 5:00PM |
V6.00003: Shock compression of precompressed deuterium Michael Armstrong, Jonathan Crowhurst, Joseph Zaug, Alexander Goncharov, Sorin Bastea, Burkhard Militzer Hydrogen and deuterium are predicted to exhibit a number of exotic phenomena at high pressure ($>$ 50 GPa) and low temperature ($<<$ 1 eV), including a roll over in the melt temperature and metallization. Experimental work to confirm these predictions is challenging for both static and dynamic techniques. Hydrogen is difficult to contain in diamond anvil cells at high pressure and $\sim $1000 K, and reaches very high temperatures ($>$ 1 eV) under single shock compression to pressures greater than 50 GPa. We address these issues via shock compression of highly precompressed ($>$ 20 GPa) deuterium in a diamond anvil cell. Generally, this method enables variation of the final state over a two dimensional region of thermodynamic phase space through independent control of the precompression and the shock compression. For deuterium, this method enables access to high pressure, $\sim 1000$ K temperature in deuterium by shock heating from a high pressure, but low temperature initial state achievable in a DAC. We generate and characterize the shocked state using an ultrafast method which enables direct measurement of both shock and particle velocity in a single shot. Here we present the results of our first experiments. [Preview Abstract] |
Thursday, June 30, 2011 5:00PM - 5:15PM |
V6.00004: Ab initio equation of state of hydrogen for inertial fusion applications Lorin X. Benedict, Miguel A. Morales, Eric Schwegler, Isaac Tamblyn, Stanimir A. Bonev, Alfredo A. Correa, Daniel S. Clark, Steven W. Haan We describe {\it ab initio} electronic structure calculations (DFT molecular dynamics and quantum Monte Carlo) of the equation of state of hydrogen in a regime relevant for ICF applications. We find the computed EOS to be quite close to that of the most recent SESAME table (constructed by G. Kerley, 2004). A simple density-dependent correction brings the recent SESAME EOS into nearly perfect agreement with ours in the chosen region. Simulations of ICF applications with this {\it corrected} SESAME table are discussed. [Preview Abstract] |
Thursday, June 30, 2011 5:15PM - 5:30PM |
V6.00005: Complex Behavior of Noble Gases under Compression B.A. Nadykto When cooled or compressed, elementary monoatomic noble gases become a condensed liquid or solid. Further compression of condensed inert gases in static experiments (for example, in diamond anvils) and shock experiments revealed a number of interesting features in their behavior under compression. The paper provides a computational analysis of experiments based on the assumption that condensed noble gases change their electron structure under compression. Even at low pressures (up to 5 GPa), compressibility of argon was observed to change drastically, which is associated with its turning solid at a pressure of P = 1.3 GPa at room temperature. At high pressures, the change in the slope of the P($\rho )$ diagram can be interpreted as a change in the outer electron shell of atoms, which is fundamental to material properties. Parameters of the high-pressure phase of xenon fitted to describe experimental data at P $<$ 100 GPa are in very close agreement with recently published data for pressures up to 840 GPa. Data of temperature measurements at megabar shock-wave pressures for argon, krypton and xenon are analyzed. Effects of electron state excitation in atoms on heat capacity and measured temperature are discussed. [Preview Abstract] |
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