Bulletin of the American Physical Society
56th Annual Meeting of the APS Division of Plasma Physics
Volume 59, Number 15
Monday–Friday, October 27–31, 2014; New Orleans, Louisiana
Session CO3: Equation of State |
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Chair: Marcus Knudson, Sandia National Laboratories Room: Salon D |
Monday, October 27, 2014 2:00PM - 2:12PM |
CO3.00001: ABSTRACT WITHDRAWN |
Monday, October 27, 2014 2:12PM - 2:24PM |
CO3.00002: Hugoniot measurements at pressures of 20-720 Mbar at the NIF Andrea Kritcher, Tilo Doeppner, Benjamin Bachmann, Dominik Kraus, Roger Falcone, Gilbert Collins, Otto Landen, Dave Chapman, Jim Hawreliak, Siegfried Glenzer, Joe Nilsen, Damian Swift Laboratory measurements of the Equation of State (EOS) of matter at high pressure, exceeding several hundred Mbar, are of great importance in the understanding and accurate modeling giant planetary formation and benchmarking dense matter models is relevant for fusion energy experiments. For example, at Gbar pressures atomic shell effects may come into play, which can change the predicted compressibility at given pressure due to pressure and temperature ionization. In this work we present the first laboratory measurements of the strong shock hugoniot at pressures up to 720 Mbar for CH and 630 Mbar for High Density Carbon (HDC). X-ray radiography has been applied to measure the shock speed and infer the mass density profile, enabling determining of the material pressure and absolute shock Hugoniot. We will also present a comparison to postshot HYDRA simulations. [Preview Abstract] |
Monday, October 27, 2014 2:24PM - 2:36PM |
CO3.00003: Penumbral Imaging of micrometer size plasma hot spots at shock stagnation in Gbar EOS experiments on the National Ignition Facility Benjamin Bachmann, A.L. Kritcher, L.R. Benedetti, R.W. Falcone, S. Glenn, J. Hawreliak, N. Izumi, D. Kraus, O.L. Landen, S. LePape, T. Ma, F. Perez, D. Swift, T. Doeppner We have developed an experimental platform for absolute equation of state (EOS) measurements up to Gbar pressures on the National Ignition Facility (NIF). We use a symmetry-tuned hohlraum drive to launch a spherical shock wave into a solid CH sphere. Streaked Radiography is the primary diagnostic to measure the density change at the shock front as the pressure increases towards smaller radii. At shock~stagnation in the center of the capsule, we observe short and bright x-ray self emission from high density (50 g/cm$^3$) plasma at 1 keV. Here, we present results obtained with penumbral imaging, carried out to characterize the size of the hot spot emission. A detailed understanding of this size and~emission strength allows for benchmarking radiation-hydro simulations in a regime that is not accessible to radiography. The application of penumbral imaging extends existing NIF diagnostic capabilities to higher spatial resolution (currently 10 $\mu$m to 1 $\mu$m) and higher sensitivity. At peak emission we find the hot spot radius to be as small as 5.8 $+$/- 1 $\mu$m, corresponding to a convergence ratio of 200. [Preview Abstract] |
Monday, October 27, 2014 2:36PM - 2:48PM |
CO3.00004: Direct Measurements of Shock-Wave Propagation in CH Using Streaked X-Ray Radiography and VISAR C.R. Stillman, P.M. Nilson, M. Lafon, C. Mileham, R. Boni, T.R. Boehly, D.D. Meyerhofer, D.H. Froula, D.E. Fratanduono Measurements of shock-wave propagation in CH were carried out with one-dimensional streaked x-ray radiography and a line-imaging velocity interferometer. The shock was driven with a 2.5-ns laser pulse at focused intensities of up to $4 \times 10^{14}$ W/cm$^2$. The shock-velocity measurements show good agreement with each other to within experimental error. This combination of techniques is being investigated for future applications in absolute equation-of-state studies. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and the Stewardship Science Graduate Fellowship Grant Number DE-NA0002135. [Preview Abstract] |
Monday, October 27, 2014 2:48PM - 3:00PM |
CO3.00005: Design and analysis of laser shock wave equation-of-state experiments on low-Z materials R. London, A. Lazicki, J. Castor, G. Collins, J. Nilsen, F. Coppari, D. Erskine, D. Fratanduono, J. Hawreliak, M. Morales-Silva, H. Whitley The equation-of-state (EOS) of low-Z materials is important for inertial confinement fusion, planetary astrophysics, and high energy density physics. Lithium hydride is both technologically important and a common benchmark for theoretical models. Experimental data at pressures above 3 Mbar was lacking, resulting in uncertainty in the high pressure EOS. Experiments at the Omega Laser Facility are being pursued to study the EOS at higher pressures. The experiments use the impedance matching technique, in which the EOS is determined from VISAR measurements of a laser-generated shock wave propagating into a LiH sample from a quartz reference. Modeling of the laser-target interaction and shock propagation using the HYDRA radiation-hydrodynamic computer program is described. We use the results to specify parameters such as the composition and thicknesses of various target layers and the laser pulse profiles. The role of x-ray and hot electron preheat on the propagation of the shock wave and the VISAR beam are described. Results are presented for the EOS of LiH between 2.5 and 10.5 Mbar. The results are compared to previous experimental data, tabulated models, and recent quantum molecular dynamics calculations. [Preview Abstract] |
Monday, October 27, 2014 3:00PM - 3:12PM |
CO3.00006: Measurements of Sound Speeds in Shocked Materials C.A. McCoy, M.C. Gregor, T.R. Boehly, D.D. Meyerhofer, D.E. Fratanduono, P.M. Celliers A new method to measure the sound velocity in shocked materials is described. The non-steady wave correction allows one to relate the shock profile in a sample to that in a reference material with a known equation of state. A comparison of arrival times of characteristic shock features in a sample to those in the reference material provides a relative measure of the sound velocity in the shocked sample. Data are presented for these sound-speed measurements in LiF and fused silica along with an absolute measurement of the sound velocity in shocked quartz---the standard to which these samples are referenced. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Monday, October 27, 2014 3:12PM - 3:24PM |
CO3.00007: Probing the Release of Shocked Material D.N. Polsin, C.A. McCoy, M.C. Gregor, T.R. Boehly, T.C. Sangster, D.E. Fratanduono, P.M. Celliers The behavior of shocked material as it releases to lower pressures is important for equation-of-state experiments and inertial confinement fusion research. We present results of experiments that used a 10-ps, 266-nm probe beam to image the release plumes of various target materials shocked to multi-megabar pressures by the OMEGA EP laser. Simultaneous VISAR (velocity interferometer system for any reflector) measurements provide the initial shocked state from which these materials release. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Monday, October 27, 2014 3:24PM - 3:36PM |
CO3.00008: The Release Behavior of Diamond Shocked to 15 Mbar M.C. Gregor, C.A. McCoy, D.N. Polsin, T.R. Boehly, D.D. Meyerhofer, D.E. Fratanduono, P.M. Celliers Ultrananocrystalline diamond (UNCD) is used as an ablator material for inertial confinement fusion experiments at the National Ignition Facility. Both the Hugoniot and the release behavior of the UNCD ablators are needed to accurately model the implosion process. The OMEGA laser was used to perform experiments in which two types of high-density carbon released into sample materials with known Hugoniots (quartz, 200 mg/cm$^{3}$ SiO$_{2}$ foam, liquid deuterium, and polystyrene). We present preliminary results of the release behavior of both UNCD and single-crystal diamond in the 5- to 15-Mbar regime. Models for the release isentropes of UNCD and single-crystal diamond will be developed using a Mie--Gr\"{u}neisen equation of state. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
Monday, October 27, 2014 3:36PM - 3:48PM |
CO3.00009: Studying the Equation of State of Isochorically Heated Al Using Streaked Optical Pyrometry D. Haberberger, P.M. Nilson, M.C. Gregor, T.R. Boehly, D.H. Froula The thermal equilibration rates of warm (few eV) dense ($\sim$ 10$^{23}$ g/cm$^3$) matter is important in high-energy-density physics. The OMEGA EP laser was used to isochorically heat a 20-$\mu$m-thick Al target using a short-pulse beam with 250 J in a 10-ps pulse. Twenty OMEGA beams were used to drive a Ti backlighter to radiograph the expansion of the foil using an x-ray framing camera (XRFC). The short duration of the heating laser pulse and the subsequent hot-electron energy deposition inside the target ensure minimal hydrodynamic expansion during the target heating phase. Streaked optical pyrometry (SOP) was used to measure the surface temperature of the foil. Together, these two measurements can be used to determine the equation of state along the release isentrope of the isochorically heated Al foil.\footnote{ M. E. Foord, D. B. Reisman, and P. T. Springer, Rev. Sci. Instrum. \textbf{75}, 2586 (2004).} Initial analysis of the SOP and XRFC data indicate the Al foil was heated to temperatures of tens of eV. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [Preview Abstract] |
(Author Not Attending)
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CO3.00010: Model for atomic dielectric response in strong, time-dependent laser fields T.C. Rensink, T.M. Antonsen, J.P. Palastro, D.F. Gordon A nonlocal quantum mechanical model is explored for calculating the atomic response to a strong laser electric field. By replacing the Coulomb potential with a nonlocal potential in the Schrodinger equation, a 3+1D calculation of the time-dependent electric dipole moment is reformulated as a 0+1D integral equation that retains the 3D dynamics. The model is benchmarked against an established ionization theory and \textit{ab initio} simulation of the time-dependent Schrodinger equation. An extension to include multiple bound states, as well as 2 color THz generation predictions are also presented. [Preview Abstract] |
Monday, October 27, 2014 4:00PM - 4:12PM |
CO3.00011: Reflectivity of CHOGe along the principal hugoniot Vanina Recoules, Gael Huser, Pierre Colin-Lalu One possible solution for the ablator of the ICF capsule is to use plastic(CH) doped with a mid-Z element such as Ge. Knowledge of the EOS and opacity of this material is then critical for target design. We have performed calculation of the equation of states (EOS) and the reflectivity along the principal Hugoniot up to 8 Mbar for two highly doped (2\% and 13\%) CHOGe mixture. We have used DFT-QMD simulation coupled with Kubo-Greenwood formulation for the optical properties. A special attention was paid on the PAW dataset design for the high pressure cases and on the Ge description. These calculations are compared to the experiment performed at Gekko XII on laser-shocked CHOGe where EOS data and optical properties were obtained in the same regime. On one hand, this study allow us to explore the mixing rule used for the EOS calculation in hydrodynamics simulation. On the other hand, this shows the capability of the description of the electronic structure modification along the metal to non-metal transition using QMD simulations. [Preview Abstract] |
Monday, October 27, 2014 4:12PM - 4:24PM |
CO3.00012: Equation of state and transport properties of silicates under extreme conditions Tingting Qi, Sebastien Hamel Understanding the physical properties of silicates under high temperature and pressure is fundamental to an accurate description of planetary interiors and evolution models. For example, earth's mantle is a rocky silicate shell constituting about 84\% of Earth's volume. Possible chemical compositions include SiO$_2$ and some other silicates such as MgSiO$_3$ and CaSiO$_3$. Moreover, Moon forming scenarios often invoke giant impacts between silicate-rich objects. Similarly, the existence of a rocky core or mantle with silicate as the major component is frequently assumed in models of giant planets, such as Jupiter or Saturn and Uranus and Neptune. Consequently, constructing planetary interior and evolution models requires knowledge of silicate's equation of state and its optical and transport properties at high pressures and temperatures. [Preview Abstract] |
Monday, October 27, 2014 4:24PM - 4:36PM |
CO3.00013: VISAR blanking due to preheating in a 2-pulses planar experiment at LULI facility Laurent Videau, Stephane Laffite, Sophie Baton, Patrick Combis, Jean Clerouin, Michel Koenig, Vanina Recoules, Christophe Rousseaux Optical diagnostics, such as VISAR (Velocity Interferometer System for Any Reflector), have become essential in shock timing experiments. Their high precisions allow an accurate measurement of shock velocities and chronometry. But, measurements can be compromised by x-ray preheating. In planar shock coalescence experiments recently performed at the LULI facility [1], VISAR signal loss was observed. In these experiments, a strong shock, launched by a high-intensity spike, catches up with a first one, initially launched by a low-intensity beam. VISAR signal disparition is due to x-ray generated by spike absorption in corona. It does not occur if high-intensity spike starts after VISAR probe beam begins to reflect off the first shock. Based on optical index assessment in quartz, VISAR diagnostic is modelized and compares favorably to experimental results. This provides evidence of the impact of x-ray preheating on VISAR absorption in quartz. \\[4pt] [1] S. D. Baton et al, Phys. Rev.Lett. 108, 195002 (2012) [Preview Abstract] |
Monday, October 27, 2014 4:36PM - 4:48PM |
CO3.00014: Characterization of Low-density Foams for Use in Strength Experiments at NIF L.R. Benedetti, A. Arsenlis, C.M. Huntington, B.R. Maddox, H.-S. Park, S. Prisbrey, B.A. Remington, C. Wehrenberg, Y.P. Opachich, M. Haugh, E. Huffman, J. Koch, E. Romano, F. Weber, M. Wilson, P. Graham To infer strength in compressed solids by observation of Rayleigh-Taylor growth, we are engaged in an experimental campaign at NIF. To produce a drive that is sufficiently cool to prevent melting and also long enough to observe growth over tens of ns, we are developing a target that mediates the high-intensity NIF laser drive by shocking a multi-component reservoir and driving the target sample by the stagnation of the reservoir's release after crossing a large gap (~1mm vacuum). This design depends on the shock and release of an ultra-low density foam layer (10-30 mg/cc), which in turn requires that these layers be well-characterized for uniformity and reproducibility. We describe efforts to characterize C and SiO2 based foam targets to quantify variations in rho-R. Our fabrication and measurement goal is taken from simulations that indicate that targets must be uniform at the 10\% level over spatial scales from 20 microns to 2 mm. We present data from differential radiography of witness samples by soft x-rays (E$<$1.5keV) and compare our results to other techniques. [Preview Abstract] |
Monday, October 27, 2014 4:48PM - 5:00PM |
CO3.00015: Laser-driven 6-16 keV x-ray imaging and backlighting with spherical crystals M. Schollmeier, P.K. Rambo, J. Schwarz, I.C. Smith, J.L. Porter Laser-driven x-ray self-emission imaging or backlighting of High Energy Density Physics experiments requires brilliant sources with keV energies and x-ray crystal imagers with high spatial resolution of about 10$\,\mu$m. Spherically curved crystals provide the required resolution when operated at near-normal incidence, which minimizes image aberrations due to astigmatism. However, this restriction dramatically limits the range of suitable crystal and spectral line combinations. We present a survey of crystals and spectral lines for x-ray backlighting and self-emission imaging with energies between 6 and 16 keV. Ray-tracing simulations including crystal rocking curves have been performed to predict image brightness and spatial resolution. Results have been benchmarked to experimental data using both Sandia's 4 kJ, ns Z-Beamlet and 200 J, ps Z-Petawatt laser systems. \\[4pt] 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. SAND NO. 2014-15552A. [Preview Abstract] |
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