Bulletin of the American Physical Society
60th Annual Meeting of the APS Division of Plasma Physics
Volume 63, Number 11
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session UO7: Equation of State |
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Chair: Peter Celliers, Lawrence Livermore National Lab Room: OCC B117-119 |
Thursday, November 8, 2018 2:00PM - 2:12PM |
UO7.00001: Preheat in x-ray driven equation-of-state experiments at the National Ignition Facility Richard A London, Michelle C Gregor, Amy E Lazicki, Peter M Celliers, Federica Coppari, Jon Henry Eggert, David J Erskine The high power and energy of the National Ignition Facility enables equation-of-state (EOS) experiments at pressures exceeding 100 Mbar. With indirect drive experiments, soft x rays at energies up to 1 keV are created in a laser-irradiated hohlraum and used to drive high pressure shock waves into EOS samples. The shock wave velocities are measured and used to extract EOS data. However, hard x rays are also created and can preheat the targets. This can alter the pre-shock conditions of the samples and compromise the EOS measurements. One such effect is the expansion of a gold layer placed in the target package to protect the sample material from preheat. This launches an elastic wave, which can perturb the sample ahead of the main shock. The role of preheat is studied with computational radiation/hydrodynamic simulations. The simulation results are used to provide a) quantitative assessment of the errors introduced by the preheat effects, b) methods to correct for the preheat effects in the analysis of the data, and c) target designs to minimize the effects. |
Thursday, November 8, 2018 2:12PM - 2:24PM |
UO7.00002: High-Pressure Behavior of Precompressed CO2 Shocked to ~10 Mbar Linda E Crandall, J. R. Rygg, G. W. Collins, T. R. Boehly, A. Jenei, D. E. Fratanduono, M. C. Gregor, J. H. Eggert, M. Millot, D. Spaulding CO2 is present in the atmospheres and interiors of Jovian planets, atmospheres of exoplanets,and within Jovian moons. To study the high-pressure behavior of CO2, we used laser-driven shocks to compress CO2 to ~1 TPa (10 Mbar). The CO2 was precompressed in diamond-anvil cells to 5 kbar, producuing liquid at density (~1.5 g/cm3), and then shocked by the OMEGA Laser System. Equation of state, temperature, optical reflectivity, and heat capacity were measured between 150 and 950 GPa. CO2 undergoes an insulator-to-conductor transition above 200 GPa, which may be the result from dissociation to metallic oxygen. These data can add to the understanding of thermochemical histories of the giant planets. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under |
Thursday, November 8, 2018 2:24PM - 2:36PM |
UO7.00003: High-Precision Hugoniot measurements for CH foams in the 2-9 Mbar range Y. Aglitskiy, A. L Velikovich, M. Karasik, A. J Schmitt, V. Serlin, J. L Weaver, J. Oh, S. P. Obenschain, K. Cochrane Absolute Hugoniot measurements for plastic foams at ~10% of solid CH density and supporting simulation results are reported. Planar foam slabs, ~400 μm thick and ~500 μm wide, some of which were covered with a 10 μm solid plastic ablator, were directly driven with 4 ns long Nike KrF 248 nm wavelength laser pulses that produced strong shock waves in the foam. The shock and mass velocities in our experiments were up to 104 km/s and 84 km/s, respectively, and the shock pressures up to ~9 Mbar. The motion of the shock and ablation fronts was recorded using side-on monochromatic x-ray imaging radiography. The steadiness of the observed shock and ablation fronts within ~1% has been verified. The Hugoniot data inferred from our velocity measurements agree with the predictions of the EOS models, such as SESAME, near the highest pressure ~9 Mbar, but from 2 to 5 Mbar, a lower shock density compression is observed than that predicted by the models. Possible causes for this discrepancy are discussed. |
Thursday, November 8, 2018 2:36PM - 2:48PM |
UO7.00004: Shock-Compressed Methane to 400 GPa G. Tabak, T. Boehly, G. Collins, L. Crandall, B. Henderson, J. R. Rygg, M. Millot, S. Ali, P. Celliers, J. Eggert, D. Fratanduono, S. Hamel, D. Hicks, A. Lazicki, D. Swift, S. Brygoo, P. Loubeyre, R. Kodama, K. Miyanishi, T. Ogawa, N. Ozaki, T. Sano, R. Jeanloz Methane plays an important role in planetary physics and is a major constituent of giant planet atmospheres. At low temperatures, methane dissociates into diamond and hydrogen above 300 GPa. This transition is predicted to occur at lower pressures with increasing temperature, supporting the idea that diamond might make up a significant fraction of the deep interior of Neptune.[1–3] We present shock-compression data to 400 GPa for methane. The methane samples were precompressed in a diamond-anvil cell so that the experiments would be relevant to giant planets. Data are referenced to a quartz standard. [1] M. Ross, Nature 292, 435 (1981). [2] M. Ross and F. Rogers, Phys. Rev. B 74, 024103 (2006). [3] G. Gao et al., J. Chem. Phys. 133, 144508 (2010). |
Thursday, November 8, 2018 2:48PM - 3:00PM |
UO7.00005: X-Ray Thomson Scattering and Radiography from Imploding Diamond Spheres on the OMEGA Laser Alison M. Saunders, Michael J. MacDonald, Ryan Nora, Amy E Lazicki, Joseph Nilsen, Dirk Gericke, Roger W. Falcone, Otto L Landen, Wolfgang R. Theobald, Tilo Doeppner X-ray Thomson scattering (XRTS) is an experimental technique that directly probes the physics of warm dense matter by measuring electron density, electron temperature, and ionization state [1]. XRTS in combination with x-ray radiography offers a unique ability to measure the equation of state of material under compression [1,2]. We present XRTS and x-ray radiography measurements taken at the OMEGA Laser Facility from directly-driven solid diamond spheres. We use the radiography data to generate post-shot radiation hydrodynamics simulations that match the observed implosion trajectory. We then use the XRTS data in combination with the benchmarked simulations to constrain the ionization state of up to three-times compressed diamond at temperatures of up to 10 eV. [1] S. H. Glenzer and R. Redmer. Rev. Mod. Phys. 81, 1625 (2009). [2] A. L. Kritcher et al., J. Phys. Conf., 688, 102055 (2016). |
Thursday, November 8, 2018 3:00PM - 3:12PM |
UO7.00006: Equation of state measurements of proton-heated warm dense matter using streaked X-ray radiography Matthew P Hill, Colin RD Brown, Emma Floyd, Steven F James, Lauren MR Hobbs, Lucy Wilson, Rory Penman, Peter Allan, David J Hoarty We report on ongoing short-pulse proton heating experiments to measure the equation of state of low-Z warm dense matter conducted at the AWE Orion laser facility. Picosecond resolution streaked X-ray radiographs were analysed using the method proposed by M. Foord et al. [Rev. Sci. Instrum. 75, 2586 (2004)] to generate isentropes, extending from 0.01 to 4 Mbar at temperatures up to 20 eV. To date, isentropes have been extracted for parylene-N plastic, boron carbide and diamond; all show a systematic disagreement with Thomas-Fermi-based predictions at low densities. The latest results are presented including attempts to use streaked optical pyrometry to measure the initial plasma temperature. |
Thursday, November 8, 2018 3:12PM - 3:24PM |
UO7.00007: Structural study of laser shocked MgO using X-rays Absorption Near Edge Spectroscopy Alessandra Benuzzi Mounaix, Riccardo Bolis, Jean-Alexis Hernandez, Vanina Recoules, Marco Guarguaglini, Fabien Dorchies, Noemie Jourdain, Alessandra Ravasio, Tommaso Vinci, Erik Brambrink, Norimasa Ozaki, Johann Bouchet, Riccardo Muselia, Stephane F Mazevet, Nicolas Hartley, Francois Guyot MgO is one of the components of rocky materials, constituting the Earth's and terrestrial planets mantles. Detailed description of his phase diagram is essential to properly model interior structures and dynamics of these planets [1]. We report first time-resolved X-ray absorption near edge spectroscopy (XANES) investigation of warm dense MgO at multi Mbar pressures. The results were obtained on the LULI 2000 at the Ecole Polytechnique using a nanosecond beam to compress a sandwiched CH/MgO/C/CH target and the picosecond beam to generate the X-ray source. With an approach previously validated on Al, we obtained XANES data at a wide range of temperature and density conditions. With the support of quantum molecular dynamic simulations we show the MgO band gap closure mechanism and the local structural properties of liquid MgO. |
Thursday, November 8, 2018 3:24PM - 3:36PM |
UO7.00008: Developing a high-flux, high-energy continuum backlighter for extended X-ray absorption fine structure measurements at the National Ignition Facility Andrew Krygier, Federica Coppari, G Elijah Kemp, Daniel Thorn, Stephen Craxton, Jon Henry Eggert, Emma M Garcia, James M McNaney, Hye-Sook Park, Yuan Ping, Bruce Allen Remington, Marilyn Beth Schneider Extended X-ray absorption fine structure (EXAFS) spectroscopy is a powerful tool for in-situ characterization of matter in the high energy density regime. An EXAFS platform is currently being developed on the National Ignition Facility (NIF). Development of a suitable X-ray backlighter involves minimizing the temporal duration and source size while maximizing spectral smoothness and brightness. One approach involves imploding a spherical shell, which generates a high-flux X-ray flash at stagnation. We present results from a series of experiments comparing the X-ray source properties produced by imploded empty and Ar-filled glow discharge polymer (GDP) capsules. We find that 1 atm and 4 atm fill pressures produce similar X-ray spectra compared to empty GDP capsules with a significant reduction in spot size. |
Thursday, November 8, 2018 3:36PM - 3:48PM |
UO7.00009: X-Ray Diffraction of Potassium in the High-Pressure Regime Xuchen Gong, Danae N Polsin, James R Rygg, Thomas Boehly, Linda E Crandall, Brian Henderson, Suxing Hu, Margaret Huff, Rahul Saha, Gilbert W Collins, Ray Smith, Jon Henry Eggert, Federica Coppari, Amy E Lazicki, Malcolm I McMahon Due to the high compressibility of alkali metals, they provide a unique window into the high-density behavior of matter at accessible pressures. We are working to quasi-isentropically compress potassium into the terapascal regime to explore the evolution of its ionic and electronic structural complexity with pressure. Theoretical predicts potassium transforms to a double hexagonal-close-packed (dhcp) structure at ~250 GPa.[1] Moreover, the melting curve is seen to drop to a minimum at ~20 GPa[2] then rising precipitously with pressure and without experimental bounds beyond 25 GPa. The high compressibility and low sound speed of potassium make it very difficult to explore these properties at high pressure. Hydrodynamic simulations are used to guide experimental designs to map these physical properties of potassium to pressures approaching 1 TPa. We show preliminary powder diffraction[3] and optical reflectivity measurements for potassium, ramp compressed to 500 GPa.
[1] P. Emma et al., Nat. Phys. 4, 641 (2010). [2] O. Narygina et al., Phys. Rev. B 84, 054111 (2011). [3] J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012). |
Thursday, November 8, 2018 3:48PM - 4:00PM |
UO7.00010: Broadband Reflectivity Diagnostic Development for Dynamic Compression Experiments on OMEGA EP Brian Joseph Henderson, Mohamed Zaghoo, Gilbert W Collins, James R Rygg, Thomas Boehly In dynamic compression experiments, materials experience dramatic changes in their physical and chemical properties, manifesting in the material’s optical properties. For experiments involving high density and temperature, reflectivity measurements are integral to detecting changes in chemical bonding and electronic structure. To this end, our work will develop a normal-incidence, visible optical reflectivity diagnostic for the OMEGA EP Laser System at the Laboratory for Laser Energetics. This diagnostic will measure the time- and wavelength-resolved reflectivity of laser-compressed materials. We will present the design of the system, its anticipated performance, and planned experiments on compressed materials. |
Thursday, November 8, 2018 4:00PM - 4:12PM |
UO7.00011: High-Pressure Phase Diagram of Silicon Reetam Paul, S. X. Hu, V. V. Karasiev Constructing accurate high-pressure phase diagrams has been one of the goals in high-energy-density sciences. The impetus for this work stemmed from the fact that silicon is of great importance in the design of inertial confinement fusion ablators and geophysics. We have employed an evolutionary algorithm-based structure-searching method, in conjunction with density-functional-theory calculations, to determine the structure for a given pressure and temperature. Previously validated stable crystalline phases—cd, bct, sh, hcp, and fcc—have been charted along with the associated triple points at pressures of up to 3.5 TPa. Once the cold curve was obtained, first‑principles lattice-dynamical and MD calculations were used to identify the phase transition boundaries and melting line based on Gibbs free energy at finite temperatures. This study has identified a new dhcp structure sandwiched in between the sh and hcp phases (34 to 40 GPa) and a fcc-to-bcc structural transition in the region of ~2.7 TPa. We will present these results with discussions about the thermodynamic and electronic properties of silicon in each identified phase. |
Thursday, November 8, 2018 4:12PM - 4:24PM |
UO7.00012: Sound Velocity in Shocked Iron to ~2500 GPa Margaret Huff, Dayne Fratanduono, Chad A McCoy, Peter M Celliers, Linda E Crandall, Brian Henderson, Mohamed Zaghoo, Jon Henry Eggert, Gilbert W Collins, James R Rygg Measurements of the sound speed in a shock-compressed material have long been sought because they provide important information about the thermodynamic derivative in the equation of state of that material at high pressure. Specifically, constraining the sound speed in iron at high pressures can be useful to planetary science and geophysics to understand core formation and dynamo physics. We present measurements of shock‑compressed iron sound speed to pressures of 400 to 2500 GPa using a novel nonsteady wave-analysis technique[1] to infer sound speed from the relative arrival times of pressure perturbations that transited the shocked iron and an adjacent reference material. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. [1] D. E. Fratanduono et al., J. Appl. Phys. 116, 033517 (2014). |
Thursday, November 8, 2018 4:24PM - 4:36PM |
UO7.00013: Simultaneous Imaging and Diffraction from Shock Compressed Germanium at the LCLS Emma Elizabeth McBride, Frank Seiboth, David McGonegle, Simone Anzellini, Leora Cooper, Mungo Frost, Eric Galtier, Sebastian Goede, Marion Harmand, Haeja Lee, Abe Levitan, Kohei Miyanashi, Bob Nagler, Inhyuk Nam, Norimasa Ozaki, Melanie Roedel, Andreas Schropp, Christopher Spindloe, Peihao Sun, Justin Wark, Jerome B Hastings, Siegfried Glenzer, Luke Fletcher By performing X-ray diffraction measurements at 10.5 keV perpendicular to the shock propagation direction, we investigate the response of germanium to shock loading. Furthermore, we present the simultaneous combination of phase contrast imaging (PCI) techniques with in situ X-ray diffraction perpendicular to the shock compression direction to further investigate multiple-wave features in laser-driven germanium. PCI allows one to take femtosecond snapshots of magnified real-space images of shock waves as they progress though matter. X-ray diffraction perpendicular to the shock propagation direction provides the opportunity to isolate and identify different waves and determine the crystal structure unambiguously. We combine these two powerful techniques simultaneously, by using the same Be lens setup to focus the fundamental beam at 8.2 keV to a size of 1.5 mm on target for PCI and the 3rd harmonic at 24.6 keV to a spot size of 2 µm on target for diffraction |
Thursday, November 8, 2018 4:36PM - 4:48PM |
UO7.00014: The equation of state of Invar alloy: a comparison of drive techniques Chad McCoy, Scott Alexander The high-pressure equation of state provides constraint on the material response at extreme conditions relevant to planetary interiors. Invar, a Fe0.64Ni0.36 alloy, helps constrain the properties of the cores of Earth and other terrestrial planets when combined with the EOS of pure Fe and Ni. Furthermore it is a common alloy frequently used in high-precision optics and electronics due to its low thermal expansion. We present measurements of the Hugoniot, overtaking-wave sound velocity, and release of Invar alloy between ~200 and ~1000 GPa using impactors launched via 2-stage light gas gun, magnetically-accelerated flyer plates, and laser-driven shocks. Results are compared between platforms to identify potential systematic uncertainties in the techniques. |
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