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 T6: Equation of State II |
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Chair: Eric Chisolm, Los Alamos National Laboratory Room: Grand Ballroom VI |
Thursday, June 30, 2011 11:00AM - 11:15AM |
T6.00001: Adiabatic release of alpha-quartz from multi-Mbar states on the principal Hugoniot Marcus Knudson, Michael Desjarlais Quartz melts near 100 GPa on the Hugoniot into a conductive fluid with appreciable reflectivity, enabling interferometric methods to be used to directly measure the shock velocity. This property of quartz has recently been exploited to significantly improve the precision for impedance matching experiments at high pressure. However, the accuracy of measurements with quartz as a standard relies on knowledge of the off-Hugoniot response. To this end, the flyer plate capability at the Sandia Z machine was used to obtain release data for quartz using a low density aerogel. Direct impact of the aerogel provided a very precise determination of the Hugoniot for the aerogel. Measurements were then made for shock waves transmitted from quartz into aerogel, thereby enabling a measurement of the release adiabat from 300-800 GPa states on the quartz Hugoniot to 50-125 GPa states on the aerogel Hugoniot. Comparisons of the experimental measurements and Quantum Molecular Dynamics calculations of quartz release adiabats will also been presented. [Preview Abstract] |
Thursday, June 30, 2011 11:15AM - 11:30AM |
T6.00002: An Equation of State for Polymethylpentene (TPX) including Multi-Shock Response Tariq Aslam, Richard Gustavsen, Nathaniel Sanchez, Brian Bartram The equation of state (EOS) of polymethylpentene (TPX) is examined through both single shock Hugoniot data as well as more recent multi-shock compression and release experiments. Results from the recent multi-shock experiments on LANL's 2-stage gas gun will be presented. A simple conservative Lagrangian numerical scheme utilizing total-variation-diminishing interpolation and an approximate Riemann solver will be presented as well as the methodology of calibration. It is shown that a simple Mie-Gruneisen EOS based off a Keane fitting form for the isentrope can replicate both the single shock and multi-shock experiments. [Preview Abstract] |
Thursday, June 30, 2011 11:30AM - 11:45AM |
T6.00003: A Review of Reshock Data for PMMA above the Phase Transition and the Implied Gruneisen Coefficient Christopher Neel, Lalit Chhabildas, William Reinhart PMMA (poly methyl methacrylate) is an important material to characterize, both as a model glassy polymer and as a window for interferometry techniques. Recently, PMMA reshock experimental results have been reported which implied a large thermal pressure component for PMMA reshocked from about 45 GPa. This work calls into question the high pressure, primary Hugoniot data the original conclusions were based on and presents an alternative explanation, namely, that the average Gruneisen coefficient, as indicated by the Mie-Gruneisen EOS, is too small to be inferred by the experimental data. [Preview Abstract] |
Thursday, June 30, 2011 11:45AM - 12:00PM |
T6.00004: Characterization of Detonation Products of RSI-007 Explosive Timothy Ager, Christopher Neel, Lalit Chhabildas PDV and VISAR have been employed to characterize the detonation products of a production quality RSI-007 explosive. The explosive was part of an exploding foil initiator (EFI) detonator assembly in which the explosive was contained within a Kovar (Fe-Ni-Co alloy) cup. The free surface of the Kovar serves as the witness plate for the interferometry measurements. Detailed shock reverberations are recorded on the witness plate and the isentropic release path of the explosive is inferred though the velocity history. Two separate window materials are bonded to the Kovar cup in subsequent experiments and are used to further determine the release state in different pressure regimes. [Preview Abstract] |
Thursday, June 30, 2011 12:00PM - 12:15PM |
T6.00005: Shock/reload response of water and aqueous solutions of ammonium nitrate Mike Morley, David Williamson The response of water and aqueous solutions of ammonium nitrate to shock loading, below 10 GPa, has been experimentally investigated. In addition to determination of the principal Hugoniot, equation of state data have been measured through ``shock/reload'' experiments using a gas-gun driven plate-impact. A Mie-Gr\"uneisen type equation of state has been applied to the liquids under investigation. The effects of initial temperature, and of weight-percentage of ammonium nitrate, on the volume-dependent Gr\"uneisen parameter are reported [Preview Abstract] |
Thursday, June 30, 2011 12:15PM - 12:30PM |
T6.00006: Equation of State of Al Based on Quantum Molecular Dynamics Calculations Dmitry V. Minakov, Pavel R. Levashov, Konstantin V. Khishchenko In this work, we present quantum molecular dynamics calculations of the shock Hugoniots of solid and porous samples as well as release isentropes and values of isentropic sound velocity behind the shock front for aluminum. We use the VASP code with an ultrasoft pseudopotential and GGA exchange-correlation functional. Up to 108 particles have been used in calculations. For the Hugoniots of Al we solve the Hugoniot equation numerically. To calculate release isentropes, we use Zel'dovich's approach and integrate an ordinary differential equation for the temperature thus restoring all thermodynamic parameters. Isentropic sound velocity is calculated by differentiation along isentropes. The results of our calculations are in good agreement with experimental data. Thus, quantum molecular dynamics results can be effectively used for verification or calibration of semiempirical equations of state under conditions of lack of experimental information at high energy densities. [Preview Abstract] |
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