Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session R6: GPS: Geophysics and Planetary Science |
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Chair: Dylan Spaulding, UC Davis Room: Broadway III/IV |
Thursday, June 20, 2019 9:15AM - 9:30AM |
R6.00001: Quasi-isentropic sound velocity measurements of deuterium-helium mixtures at planetary interiors conditions in reverberating shocks experiments Zhi-Guo Li, Qi-Feng Chen, Yun-Jun Gu, Jun Zheng, Cheng-Jun Li The sound velocities of materials under high pressures and temperatures are important in characterizing the elasticities and phase changes, and especially crucial for our understanding of the seismic structures in planetary interiors. As the simplest elements, deuterium and helium can be well used as the standard test cases for the sound velocity studies. Moreover, deuterium and helium are major constituents of astrophysical objects such as stars and giant planets, and also the primary constituents in inertial confinement fusion (ICF). The knowledge of their physical properties such as sound velocities and equations of state (EOSs) at extreme conditions play a vital role in the constructions of giant planets interiors models and the understanding of fundamental physical processes in ICF. In this work, we perform a serious of reverberating shocks experiments on deuterium-helium (D-He) mixtures, yielding for the first time measurements of the isentropic sound velocity and EOS in a wide pressure regime. The measured sound velocity and EOS of D-He mixtures reached an unexplored range of pressure up to 120 GPa, which is direct relevant to the molecular region of giant planet interiors. The wide-range experimental data are used to validate the state-of-the-art first-principle simulation techniques and chemical models. Finally, the sound velocities data can provide more direct constraints on the seismic structure of giant planets [Preview Abstract] |
Thursday, June 20, 2019 9:30AM - 9:45AM |
R6.00002: Optical properties of warm dense fluid helium at jovian planet interior conditions Marius Millot, Stephanie Brygoo, Paul Loubeyre, Peter Celliers, Gilbert Collins, Jon Eggert, Ryan Rygg, Damian Swift, Raymond Jeanloz In contrast to hydrogen, helium does not participate in molecular bonds and therefore constitutes an excellent prototypical system to test quantum simulation and theories of metallization and ionization in the warm dense regime. To reveal the role of density and temperature on the ionization of helium going beyond the conditions explored in previous studies we conducted a series of laser-driven shock compression experiments at the Omega Laser facility, using precompressed targets with initial pressures up to 6 GPa. We will discuss how the new VISAR velocimetry and streaked optical pyrometry (SOP) data provide stringent benchmarks on the thermodynamics and electronic structure of helium at extreme conditions relevant for the understanding of the formation, evolution and structure of giant planets. Part of this work was performed at LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, June 20, 2019 9:45AM - 10:00AM |
R6.00003: Fast deformation of shocked quartz and implications for planar deformation features observed in shocked quartz. Toshimori Sekine, Tomoko Sato, Norimasa Ozaki, Kohei Miyanishi, Ryosuke Kodama, Yusuke Seto, Yoshinori Tange, Subodh Tiwan, Aiichiro Nakano, Priya Vashishta Planar deformation feature (PDF) sets observed in quartz provide an evidence for shock events. PDFs consist of the narrow, individual planar features of amorphous material, and their specific crystallographic orientations are related to a limited range of peak shock pressure. A comparison of PDFs observed in quartz between natural samples and experimental samples recovered at known conditions gives pressure estimation in natural shock events. However, the detailed mechanism is not fully understood yet, especially due to the fast formation process. We have tried to observe in time-resolved way by a direct diffraction method during shock compression and by a large scale molecular dynamics simulations. These results indicate that PDF formation, as well as planar fracture (PF) and rotation of crystallites, may occur during shock compression process even in elastic compression region. We need to know the changes during the release process in order to understand the shock effects in quartz. [Preview Abstract] |
Thursday, June 20, 2019 10:00AM - 10:15AM |
R6.00004: Precompressed Hugoniots of Hydrogen-Helium Mixtures from Density Functional Theory Raymond Clay Understanding the behavior in hydrogen helium mixtures at extreme conditions is critically important to constructing quantitative models of Jovian planet evolution. In particular, the presence of an immiscibility transition in the atmosphere of Saturn is required to explain its unusually high luminosity compared to Jupiter. As multiple experimental platforms are working towards observing this transition in the lab, it is important to cross validate experimental results ab initio calculations at temperature and pressure conditions leading up to this transition. To this end, we present in this work several precompressed Hugoniots of hydrogen-helium mixtures calculated within density functional theory based molecular dynamics, over thermodynamic regimes of relevance for upcoming ramp compression style experiments. [Preview Abstract] |
Thursday, June 20, 2019 10:15AM - 10:30AM |
R6.00005: Dynamic Strength Measurements of Meteorites Dawn Graninger, Benjamin Brugman, Laura Riordan-Chen, Eric B. Herbold, Susannah M. Dorfman, Damian Swift, Megan Syal Simulations of impacts during both planetary accretion and for planetary defense rely on material properties of impacted bodies, most of which may be chondritic. However, as the dynamic response of chondrite to shock is poorly understood, shock properties of more common terrestrial rocks, such as granite or basalt, are often used in models as an approximation. We aim to increase the knowledge of chondritic material properties through measurements of dynamic strength. Global measurements of dynamic strength under high strain rates produced via laser shock were obtained with the Janus laser at the Jupiter Laser Facility and Velocity Interferometer System for Any Reflector (VISAR). The VISAR was used to observe the shock compression of Tamdakht, Allende, and recovered Antarctic meteorites. These measurements will help to inform planetary-scale models and provide a unique dataset for comparison with the compositional analysis of these meteorite samples. [Preview Abstract] |
Thursday, June 20, 2019 10:30AM - 10:45AM |
R6.00006: Traces of Hiroshima: a forensic investigation of shocked recovered samples Camelia Veronica Stan, Hans-Rudolf Wenk, Nobumichi Tamura The bombing of Hiroshima lead to the volatilization of a large volume of material due to the high pressures and temperatures generated during the blast. These dynamically shocked conditions lead to the synthesis of completely new materials that would subsequently be deposited within some distance of the original hypocenter. In this study, we have discovered and analyzed a selection of sands from Motoujina Peninsula, 6 km south of the hypocenter. Using a variety of techniques, including scanning electron microscopy with energy dispersive spectroscopy, and x-ray fluorescence combined with powder microdiffraction, we have identified these as compositionally and morphologically distinct from the prevailing local mineralogy. Because of this, the volume of particles found, and the absence of other viable anthropogenic sources of formation, we conclude that the diverse glass particles originated from the Hiroshima event and were formed at temperatures exceeding 2000 K combined with rapid cooling. [Preview Abstract] |
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