Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session J4: HD-2: Giant Planets |
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Chair: Marcus Knudson, Sandia National Laboratories Room: Hermitage D |
Tuesday, June 30, 2009 11:00AM - 11:30AM |
J4.00001: Interior structure of solar and extrasolar giant planets Invited Speaker: Molecular dynamics simulations combined with finite-temperature density functional theory (FT-DFT-MD) represent a powerful novel tool to calculate accurate equation of state (EOS) data. Comparison with shock wave experiments yields good agreement for the Hugoniot curve, the reflectivity, and the electrical conductivity for the most abundant materials in giant planets such as hydrogen, helium, and water, especially in the warm dense matter region. Based on this new ab initiodata we discuss the nonmetal-to-metal transition in hydrogen, the demixing of hydrogen and helium at megabar pressures, the location of the superionic phase in water, and the respective high-pressure phase diagrams. Most importantly, the availability of more data will lead to modified or completely new interior structure models for solar as well as extrasolar giant planets. Key issues are in this context the core mass, the metallicity, and the cooling curve. We present recent results for the interior structure of solar giant planets. First predictions for the structure and composition of selected extrasolar giant planets such as GJ 436b are also given based on ab initioEOS data. [Preview Abstract] |
Tuesday, June 30, 2009 11:30AM - 11:45AM |
J4.00002: Semiempirical multiphase equation of state of liquid hydrogen Pyalling Alexei Semiempirical equations of state for dielectric and plasma phases of liquid hydrogen were constructed. Dielectric phase was modeled as dissociating molecular -- atomic mixture. This allowed to reproduce experimental results for single shock compressed hydrogen. Equilibrium line of plasma phase transition was built. For quasi isentropic compression the plasma phase transition occurs at the pressure 130 GPa, according to the current model. Model reproduces the experimental results for conductivity of compressed hydrogen under assumption that plasma phase clusters are formed in the dielectric phase of hydrogen. [Preview Abstract] |
Tuesday, June 30, 2009 11:45AM - 12:00PM |
J4.00003: Conductivity measurements of multi-shock compressed deuterium J.R. Rygg, D.G. Hicks, R.F. Smith, G.W. Collins, O.L. Landen The transport properties of compressed hydrogenic materials affect the stability of accelerating inertial confinement fusion targets and the structure of gas-giant planets. Calculation of the electrical and thermal conductivities of hydrogen and deuterium is particularly challenging in the region of transition from an insulating molecular to a metallic state (near 1 MBar and several thousand K), because in this region the conductivities change by several orders of magnitude. Deuterium samples were compressed through this region up to multiple MBar by a sequence of laser-driven shocks. Results of simultaneous pressure, temperature, and optical reflectivity measurements of these samples will be reported. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM {\#}LLNL-ABS-405478. [Preview Abstract] |
Tuesday, June 30, 2009 12:00PM - 12:15PM |
J4.00004: Conductivity of multiple shock compressed hydrogen along 135 and 180 GPa isobars Vladimir Ternovoi, Alexei Pyalling, Dmitry Nikolaev, Sergey Kvitov The results of temperature and conductivity measurements of hydrogen, multiple shock compressed to the pressures 135 and 180 GPa are presented. Explosively driven steel plate with velocity up to 8 km/s was used for shock wave generation. Hydrogen with different initial pressures and temperatures was multiple shock compressed between steel bottom and sapphire window. Brightness temperature of hydrogen was measured by fast optical pyrometer. Electrical resistance of shocked hydrogen was measured simultaneously with optical pyrometer records. The conductivity of hydrogen decreased from 424 1/Om/cm at 2700 K down to 20 1/Om/cm at 6000 K along 135 GPa isobar. The conductivity of hydrogen decreased from 800 1/Om/cm at 5000 K down to 100 1/Om/cm at 6700 K along 180 GPa isobar. Experimental results are compared with different theoretical predictions. [Preview Abstract] |
Tuesday, June 30, 2009 12:15PM - 12:30PM |
J4.00005: Dynamic Conductivity of Dense Hydrogen in Wigner Formulation of Quantum Mechanics Vladimir Filinov, Pavel Levashov, Michael Bonitz, Vladimir Fortov Combining both molecular dynamics and Monte Carlo methods for solving the integral Wigner-Liouville equation we calculate the temporal momentum-momentum correlation functions, their frequency-domain Fourier transforms and dynamic electrical conductivity by the Kubo formula. Alternatively, at low temperature we use the density functional theory and the Greenwood formula to obtain frequency-dependent electrical conductivity. In the canonical ensemble at finite temperature for weakly coupled plasmas the obtained numerical results agree well with the Drude approximation. The growth of coupling parameter results in strong deviation of the frequency dependent conductivity and permittivity from low density and high temperature approximations. In particular, slowly-damping oscillations on the momentum-momentum temporary correlation functions can be observed, and the transparency window appears on the dependencies of electrical conductivity on frequency. We compare our results with experimental data and other theories. [Preview Abstract] |
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