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 E4: High Energy Density Physics/Warm Dense Matter I |
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Chair: Tommy Ao and Gordon Leifeste, Sandia National Laboratories Room: Grand H |
Monday, June 15, 2015 3:30PM - 3:45PM |
E4.00001: Ab initio and experimental studies of glow-discharge polymer used in Laser M\'{e}gaJoule capsules Pierre Colin-Lalu, Ga\"el Huser, Vanina Recoules, Gwenael Salin Equations of state tables used in Initial Confinement Fusion capsule design tools are highly dependent on the cold curve in the multimegabar range. Original ab-initio molecular dynamic simulations were performed to get accurate cold curves of glow-discharge polymer (GDP) plastics. Furthermore the effect of oxygen absorption by GDP structure is studied on the cold curve, as well as its impact on the Hugoniot curves. Results are compared with Hugoniot experimental data obtained in a recent experiment at the LULI2000 laser facility in France. This study leads to improve equation of states knowledge of ablator materials, which is of primary importance for NIF and LMJ experiments. [Preview Abstract] |
Monday, June 15, 2015 3:45PM - 4:00PM |
E4.00002: Analysis of NIF experiments Yi-Ming Wang A minimal energy implosion-scaling model was recently developed to characterize the physical properties of the hot spot in terms of the peak implosion energy. In this model, the hot spot energy, volume, pressure, mass and areal density at the stagnation time are uniquely determined by the peak implosion velocity, the equation of state and the adiabat of the pusher and the DT fuel (cold and hot) at the peak implosion time. In this work, we apply this model to a number of published low-foot and high-foot experiments performed at the National Ignition Facility. Our model analysis is in a good agreement with the experimental data when a high adiabat is assumed for both low and high foot experiments. Implications of the results are discussed. [Preview Abstract] |
Monday, June 15, 2015 4:00PM - 4:30PM |
E4.00003: High Energy Density Studies at the OMEGA laser facility Invited Speaker: Thomas Boehly The primary emphasis of the scientific program at the Laboratory for Laser Energetics is laser-driven inertial confinement fusion. We report on high-energy-density (HED) experiments that use the OMEGA laser to produce multi-megabar shocks in materials of interest to the national fusion effort and the associated HED sciences. We present measurements of the behavior of shocked diamond, in both the single-crystal and ultranano-crystalline forms used as an ablator material in fusion capsules. Using the impedance-matching technique both the Hugoniot and release behaviors are measured with respect to multiple reference materials. The release of shocked diamond into liquid deuterium is also measured. We present the results of sound-speed measurements in shocked quartz which is also used as a reference for sound speed measurements in CH and fused silica. This is done using an unsteady wave analysis that tracks the propagation of small perturbations in shock pressure as they traverse the shocked material from `piston' to shock front. The arrival times of these perturbations, as compared to the same in a reference material, provides the sound speed in the shock material. We also present results of optical and x-ray probing of shock waves in foam targets and solid targets, as well as the release plumes of shock material after shock breakout. The import of these measurements to the fusion program and basic HED science will be discussed and plans for future work presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. [Preview Abstract] |
Monday, June 15, 2015 4:30PM - 4:45PM |
E4.00004: Direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium Marcus Knudson, Michael Desjarlais, Andeas Becker, Raymond Lemke, Kyle Cochrane, Mark Savage, David Bliss, Thomas Mattsson, Ronald Redmer Recently a so-called shock-ramp platform has been developed on the Sandia Z Accelerator to access off-Hugoniot states in liquids. The accelerator delivers a two-step current pulse; the first accelerates the electrode to a reasonably constant velocity, which upon impact with the sample cell creates a well-defined shock, the subsequent current rise produces ramp compression from the initially shocked state. This technique generates relatively cool ($\sim$1-2 kK), high pressure ($>$300 GPa), high compression ($\sim$10-15 fold compression) states, allowing experimental access to the region of phase space where hydrogen is predicted to undergo a first-order phase transition from an insulating molecular-like liquid to a conducting atomic-like liquid. In this talk we will discuss the experimental platform, survey the various theoretical predictions for the liquid-liquid, insulator-to-metal transition in hydrogen, and present the results of experiments that clearly show an abrupt transition to a metallic state. 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. [Preview Abstract] |
Monday, June 15, 2015 4:45PM - 5:00PM |
E4.00005: Density functional theory approach for calculation of dielectric properties of warm dense matter Ilnur Saitov The reflectivity of shocked xenon was measured in the experiments of Mintsev and Zaporoghets for wavelength 1064 nm [1]. But there is no adequate theoretical explanation of these reflectivity results in the framework of the standard methods of nonideal plasma theory. The assumption of significant width to the shock front gives a good agreement with the experimental data. However, there are no evidences of this effect in the experiment. Reflectivity of shocked compressed xenon plasma is calculated in the framework of the density functional theory approach as in [2]. Dependencies on the frequency of incident radiation and on the plasma density are analyzed. The Fresnel formula for the reflectivity is used. The longitudinal expression in the long wavelength limit is applied for the calculation of the imaginary part of the dielectric function. The real part of the dielectric function is calculated by means of the Kramers-Kronig transformation. The approach for the calculation of plasma frequency is developed [3]. \\[4pt] [1] V.B. Mintsev, Yu.B.Zaporogets. Contrib. Plasma Phys. 29, 493 (1989).\\[0pt] [2] M.P. Desjarlais. Contrib. Plasma Phys. 45, 300 (2005).\\[0pt] [3] G.E. Norman, I.M. Saitov, V.V. Stegailov, P.A. Zhilyaev Phys. Rev. E. (2015) (in press.) [Preview Abstract] |
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