Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session T5: Equation of State IX: Gases |
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Chair: Marius Millot, Lawrence Livermore National Laboratory, Dana Dattelbaum, Los Alamos National Laboratory Room: Grand I/J |
Thursday, June 18, 2015 11:15AM - 11:30AM |
T5.00001: Ethane-xenon mixtures under shock conditions Dawn Flicker, Rudolph Magyar, Seth Root, Kyle Cochrane, Thomas Mattsson Mixtures of light and heavy elements arise in inertial confinement fusion and planetary science. We present results on the physics of molecular scale mixing through a validation study of equation of state (EOS) properties. Density functional theory molecular dynamics (DFT/QMD) at elevated-temperature and pressure is used to obtain the properties of pure xenon, ethane, and various compressed mixture compositions along their principal Hugoniots. To validate the QMD simulations, we performed high-precision shock compression experiments using Sandia's Z-Machine. A bond tracking analysis of the simulations correlates the sharp rise in the Hugoniot curve with completion of dissociation in ethane. DFT-based simulation results compare well with experimental data and are used to provide insight into the dissociation as a function of mixture composition. Interestingly, we find that the compression ratio for complete dissociation is similar for ethane, Xe-ethane, polymethyl-pentene, and polystyrene, suggesting that a limiting compression exists for C-C bonded systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Thursday, June 18, 2015 11:30AM - 11:45AM |
T5.00002: Development of a Cryogenic Capability for Shock Compression of Liquid Helium on the Z machine Andrew Lopez, Seth Root, Keegan Shelton, Jose Villalva, David Hanson A cryogenic system has been developed to generate liquid helium (LHe) samples at 2.1 K for high precision equation-of-state (EOS) and isentropic compression measurements using the Z machine. Accurate data on He properties at Mbar pressures are critical to understanding gas giant planetary interiors and for validating first principles density functional simulations; however, limited high pressure He EOS data exist due to difficulty in condensing LHe samples (\textless 3.5 K) for gas guns, magnetic and explosive devices and laser facilities. To address this need, we have developed and demonstrated a cryogenic system to generate quiescent superfluid LHe samples (2.1 K). The cryostat system utilizes a conduction refrigerator with a pumped LHe reservoir to cool the cryocell. The cryostat design produces stable, controlled temperatures resulting in well-characterized initial states of liquid He samples, which is key for precision EOS measurements. Sandia National Laboratories is a multiprogram 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 No. DE-AC04-94AL85000. [Preview Abstract] |
Thursday, June 18, 2015 11:45AM - 12:00PM |
T5.00003: Shock Compression Response of the Light Noble Gases: Neon and Helium Seth Root, Luke Shulenburger, Kyle Cochrane, Andrew Lopez, Keegan Shelton, Jose Villalva, Thomas Mattsson Understanding material behavior at extreme conditions is important to a wide range of processes in planetary astrophysics and inertial confinement fusion. Modeling the high pressure - high temperature processes requires robust equations of state (EOS). For many materials, EOS models have been developed using low-pressure Hugoniot data. Assumptions are made to extrapolate the EOS models to Mbar pressure regimes, leading to different model behavior at extreme conditions. In this work, we examine the high pressure response of the light noble gases: neon and helium in the multi-Mbar regime. We perform a series of shock compression experiments using Sandia's Z-Machine on cryogenically cooled liquids of Ne (26 K) and He (2.2 K) to measure the Hugoniot and reshock states. In parallel, we use density functional theory methods to calculate the Hugoniot and reshock states. The experiments validated the DFT simulations and the combined experimental and simulation results are used to assess the EOS models. 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 Securities Administration under Contract No. DE-AC04-94AL85000. [Preview Abstract] |
Thursday, June 18, 2015 12:00PM - 12:15PM |
T5.00004: Hydrodynamic Simulations of Gaseous Argon Shock Experiments Daniel Garcia, Dana Dattelbaum, Peter Goodwin, John Morris, Stephen Sheffield, Michael Burkett The lack of published Argon gas shock data motivated an evaluation of the Argon Equation of State (EOS) in gas phase initial density regimes never before reached. In particular, these regimes include initial pressures in the range of 200-500 psi (0.025 -- 0.056 g/cc) and initial shock velocities around 0.2 cm/$\mu$s. The objective of the numerical evaluation was to develop a physical understanding of the EOS behavior of shocked and subsequently multiply re-shocked Argon gas initially pressurized to 200-500 psi through Pagosa numerical hydrodynamic simulations utilizing the SESAME equation of state. Pagosa is a Los Alamos National Laboratory 2-D and 3-D Eulerian hydrocode capable of modeling high velocity compressible flow with multiple materials. The approach involved the use of gas gun experiments to evaluate the shock and multiple re-shock behavior of pressurized Argon gas to validate Pagosa simulations and the SESAME EOS. Additionally, the diagnostic capability within the experiments allowed for the EOS to be fully constrained with measured shock velocity, particle velocity and temperature. The simulations demonstrate excellent agreement with the experiments in the shock velocity/particle velocity space, but note unanticipated differences in the ionization front temperatures. [Preview Abstract] |
Thursday, June 18, 2015 12:15PM - 12:30PM |
T5.00005: ABSTRACT WITHDRAWN |
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