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 D6: HED: Shock and Ramp Compression II |
Hide Abstracts |
Chair: Jack Wise, SNL Room: Broadway III/IV |
Monday, June 17, 2019 2:00PM - 2:15PM |
D6.00001: Shock Compression Response of Calcium Fluoride (CaF$_{\mathrm{2}})$ Seth Root, Michael Desjarlais, Patricia Kalita, Chad McCoy, Scott Alexander Fluorite, a textbook crystal structure named after CaF$_{\mathrm{2}}$, is observed in many materials such as Mg$_{\mathrm{2}}$Si, and CeO$_{\mathrm{2}}$. Specifically, CaF$_{\mathrm{2}}$ is a useful material for studying the fluorite structure because it is readily available as a single crystal. Under static compression, CaF$_{\mathrm{2\thinspace }}$is known to have at least three solid phases: fluorite, cotunnite, and a Ni$_{\mathrm{2}}$In phase. Along the Hugoniot CaF$_{\mathrm{2}}$ undergoes a fluorite to cotunnite phase transition, however, at higher shock pressures it is unknown whether CaF$_{\mathrm{2}}$ undergoes another solid phase transition or melts directly from the cotunnite phase. Historical work by Al'shuler \textit{et al }[1]$. $showed that CaF$_{\mathrm{2}}$ became highly incompressible above 100 GPa. In this work, we conducted planar shock compression experiments on CaF$_{\mathrm{2}}$ using Sandia's Z-machine and a two-stage light gun up from 60 GPa to 900 GPa. Additionally, we conducted decaying shock experiments at the Omega Laser Facility to measure temperature along the Hugoniot. We use density functional theory (DFT) based quantum molecular dynamics (QMD) simulations to provide insight into the CaF$_{\mathrm{2\thinspace }}$state along the Hugoniot. We also compare the experimentally measured temperatures to the DFT calculations. [1] L. V. Al'tshuler \textit{et al.} Sov. Phys. Solid State \textbf{15}, 969, (1973) [Preview Abstract] |
Monday, June 17, 2019 2:15PM - 2:30PM |
D6.00002: Absolute measurement of the compression of deuterium along isentropes to multi-TPa pressures P. M. Celliers, A. Fernandez-PaƱella, S. Brygoo, D. Swift, S. J. Ali, S. W. Haan, M. Millot, J. H. Eggert, D. E. Fratanduono Equation of state models for deuterium and other light elements have traditionally been tested experimentally along Hugoniots, primarily the principal Hugoniot. The compression path of DT fuel in inertial confinement fusion (ICF) follows isentropes to very high density, where little experimental data on the density compression exist. We are developing an experimental platform to compress deuterium along isentropes similar to the ICF paths using the National Ignition Facility. Our approach combines spherical geometry with multi-shock reverberation to achieve near isentropic compression to multi-TPa pressures. The sample volume is diagnosed with radiographic techniques. Our goal is to measure compression paths relevant to current ICF platforms. We will describe details of the approach and show preliminary compression data approaching 10 TPa. [Preview Abstract] |
Monday, June 17, 2019 2:30PM - 2:45PM |
D6.00003: Improved analysis of converging shock experiments for absolute equation of state and opacity Damian Swift, Amy Lazicki, Andrea Kritcher, Madison Martin, Natalie Kostinski, Brian Maddox, Tilo Doeppner, Heather Whitley, Alison Saunders, Joseph Nilsen We have previously reported absolute shock Hugoniot and opacity deduced from radiographic measurements of spherically-converging shocks, by describing the radius-time density distribution using analytic functions and performing iterative optimization to match the measured radiograph. The form of the density distribution was not guided by the physics of the experiment, other than by the known density ahead of the shock. We have recently investigated the variation of shock density and sound speed with shock speed for a variety of equations of state, and the variation of opacity with shock pressure. These quantities are closely related to the experimental observables, and we find that parameterizing the problem in this way leads to a more efficient and robust analysis with smaller uncertainties. Similar results can be obtained with parameterized relations between shock speed and particle speed, and Grueneisen parameter and density. In either case, the experiments can now be used to obtain isentropic derivative data along the Hugoniot, as well as the Hugoniot data. We show example results for diamond. [Preview Abstract] |
Monday, June 17, 2019 2:45PM - 3:00PM |
D6.00004: Atomic and Electronic Structure of Warm Dense Silicon Rahul Saha, Jacob Topp-Mugglestone, Gianluca Gregori, Thomas Boehly, Gilbert Collins, Sean Regan, Thomas White, Ryan Rygg We propose experiments to determine the atomic and electronic~structure of warm dense silicon using simultaneous spectrally and~angularly resolved measurements of the x-ray scattering. A~variety of~uniform warm dense states spanning the solid--liquid boundary will be~generated through laser shock compression of silicon samples. A unified~analysis of the x-ray scattering, combining spectral (x-ray Thomson~scattering) and angular (x-ray diffraction) scattering data, will reduce~the necessary model assumptions used to determine the ion and electron~structure factors. This will thereby reduce systematic uncertainties and mitigate inverse problem instabilities arising from simulations with large parameter spaces. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700