Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session B6: HED: Silicates and Oxides |
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Chair: Christopher Seagle, SNL Room: Broadway III/IV |
Monday, June 17, 2019 9:15AM - 9:45AM |
B6.00001: Quantum Hydrodynamics and Warm Dense Matter Invited Speaker: Frank Graziani The experimental and computational investigation of both equilibrium and non-equilibrium strongly coupled systems with partially or fully degenerate electrons is an intellectually stimulating and scientifically challenging problem. Warm dense matter (WDM) is of particular interest since it “ exists in the lower-temperature portion of the high energy density regime, under conditions where the assumptions of both condensed-matter theory and ideal-plasma theory break down, and where quantum mechanics, particle correlations, and electric forces are all important.” [FESAC 2009]. Interiors of giant planets, brown dwarfs, and neutron star envelopes are all examples of WDM. A wide variety of theoretical methods have been developed and are in routine use for studying warm dense matter. This includes density functional theory, time-dependent density functional theory, and quantum kinetic theory. Recently, there has been a resurgence in interest in using a “simpler” approach to investigating WDM based on quantum hydrodynamics. Quantum Hydrodynamics (QHD) has a long and interesting history, dating back to the first developments by Madelung and Bohm. In this talk, we discuss the historical and recent developments in QHD, including its advantages and limitations. We discuss recent numerical approaches using QHD, including the work of Larder et al. based on Bohmian trajectories and the work of D. Michta who has developed a hybrid QHD-molecular dynamics code with an application to stopping power in WDM. [Preview Abstract] |
Monday, June 17, 2019 9:45AM - 10:00AM |
B6.00002: Multiphase equations of state for magnesium oxide, silicon dioxide, and forsterite Travis Sjostrom We detail new extended range multiphase equations of state for MgO, SiO$_2$, and Mg$_2$SiO$_4$. Particular attention is paid to the warm dense liquid regime where we have performed density functional theory (DFT) based quantum molecular dynamics for densities up to 3 times ambient density and temperatures up to 100 eV. Additionally we make use of DFT results to constrain the EOS for thermally excited solids phases and the melt curve. Significant comparisons are made with experimental data and distinction is made between the accuracies of the simulation and experimental data. [Preview Abstract] |
Monday, June 17, 2019 10:00AM - 10:15AM |
B6.00003: Equation of State Calculations of Warm Dense MgSiO$_3$ Felipe Gonzalez, Henry Peterson, Francois Soubiran, Burkhard Militzer The equation of state of MgSiO$_3$ is of significant interest in planetary science and high pressure physics. In order to provide a comprehensive theoretical description of this material at extreme conditions, we combine results from path integral Monte Carlo (PIMC) and density functional molecular dynamics simulation, and generate a consistent equation of state for MgSiO$_3$. We consider a wide range of temperature and density conditions ranging from 10$^4$ to 10$^8$ K and 0.1- to 20-fold the ambient density. We derive the shock Hugoniot curve and compare with experimental results. We study how the L and K shell electrons are ionized with increasing temperature and pressure. Finally we analyze the heat capacity and structural properties of the liquid. [Preview Abstract] |
Monday, June 17, 2019 10:15AM - 10:30AM |
B6.00004: An Extended X-Ray Absorption Fine Structure Spectroscopy Study of Iron and Iron Oxide David Alexander Chin, Philip Nilson, John Ruby, Gilbert Collins, Tom Boehly, Ryan Rygg, Dustin Trail, Yuan Ping, Federica Coppari, Marion Harmand To increase our understanding of the formation and evolution of the Earth and iron-rich exoplanets, extended x-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe and FeO ramp compressed to core Earth conditions. On the OMEGA laser,\footnote{ T. R. Boehly \textit{et al.}, Opt. Commun. \textbf{133}, 495 (1997).} Fe and FeO were laser compressed to 500 GPa and probed with a broadband x-ray source. A velocity interferometer system for any reflector (VISAR) characterized the pressure in the compressed material. A newly constructed von Hamos geometry spectrometer, with a highly annealed pyrolytic graphite (HAPG) crystal, obtained the absorption spectrum from the Fe and FeO. The EXAFS data was analyzed using FEFF and GNXAS to determine the local structure, density, and temperature of the compressed material. Preliminary data will be discussed herein. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority. [Preview Abstract] |
Monday, June 17, 2019 10:30AM - 10:45AM |
B6.00005: The equation of state of Invar alloy and systematic uncertainties in modeling the re-shock Hugoniot in quartz Chad McCoy The high-pressure equation of state provides constraint on the material response at extreme conditions relevant to planetary interiors. Invar, a Fe0.64Ni0.36 alloy, helps constrain the properties of the cores of Earth and other terrestrial planets when combined with the EOS of pure Fe and Ni. Furthermore, it is a common alloy frequently used in high-precision optics and electronics due to its low thermal expansion. Measurements of the principal Hugoniot between \textasciitilde 200 and \textasciitilde 1000 GPa using impactors launched via 2-stage light gas gun, magnetically-accelerated flyer plates, and laser-driven shocks are presented. Results demonstrate a systematic difference between direct-impact and laser-driven experiments which can be attributed to use of the quartz release model to calculate the re-shock Hugoniot. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology {\&} Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. [Preview Abstract] |
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