Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session B04: EOS Fundamental Design, Modeling and Experiments IFocus Recordings Available
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Chair: Christine Wu, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 2 |
Monday, July 11, 2022 9:15AM - 9:30AM |
B04.00001: High precision equation of state measurements of Ta ramp compressed to 2.3 terapascals Martin G Gorman, Raymond F Smith, William Schill, David G Braun, Damian C Swift, Richard Briggs, Travis Volz, Earl F O'Bannon, Peter M Celliers, Dayne E Fratanduono, Jon H Eggert, Suzanne J Ali, James M McNaney The generation of extreme pressure conditions within the laboratory has led to numerous discoveries transforming our understanding of material behavior at high pressure (> 1 TPa and 298 K). At these extreme pressure conditions, theorists predict new exotic quantum states of matter, but few experimental measurements have been reported to constrain modeling at these conditions. Laser-driven ramp compression is an experimental technique which allows materials to be studied in their solid forms at extremely high densities, inaccessible by any other experimental method. Here, we report quasi-absolute EOS measurements on tantalum to 2.3 TPa , along the principal isentrope. Tantalum is a widely used reference standard and these measurements improve EOS models which are critical to our understanding of how bonding, crystal structures, and transport properties change at extreme pressures. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. |
Monday, July 11, 2022 9:30AM - 10:00AM |
B04.00002: A discussion on Equation of State modeling/generation leveraging practical approaches. Invited Speaker: Scott D Crockett A demonstration on how to model a complex Equation of State (Bismuth) starting from a simplified approach will be presented. The work was inspired from the works of Johnson, Hayes, and Asay(1). Although the models used here for our EOS are slightly more complex than in the past, we are able to leverage optimization methods which aid in producing a reasonable approximation to the EOS similar to that of Cox(2). We will be leveraging recent data and ab initio calculations for the parameterization of the models. As we further enable our modeling framework with analysis methods such as Markov chain Monte Carlo (MCMC) and Particle Swarm Optimization (PSO), accounting for systematic error in theoretical or experimental data becomes vitally important. For most EOS, the standard models are often under constrained or over fitted and require expert judgement. Yet, quantifying expert judgement remains a mystery as to how best to capture said uncertainty. |
Monday, July 11, 2022 10:00AM - 10:15AM |
B04.00003: A new equation of state for 304L stainless steel Travis Sjostrom A new equation of state for 304L stainless steel has been built and entered in the Los Alamos National Lab. SESAME database. The equation of state is based on a multiphase approach. The solid and liquid phases were fitted to available experimental data for thermal expansion, heat capacity, and shock Hugoniot, as well as to data from density functional theory calculations of the cold curve and quantum molecular dynamics of the liquid regime. The electronic thermal contribution over the entire equation of state range is based on Tartarus (Green's functions) average atom calculations. For this low-carbon stainless steel both the density functional and electronic thermal calculations are comprised of 19 wt% Cr, 10 wt% Ni, and the remainder Fe. |
Monday, July 11, 2022 10:15AM - 10:30AM |
B04.00004: The UTri Equation of State Table Format John H Carpenter For at least 60 years, tabular equation of state models have been ubiquitous in physics codes for their acceleration of state evaluations over direct calculations of analytic equations, or more costly computational models. These tables most commonly rely on interpolation of pressure and internal energy across a Cartesian grid in density-temperature space, as seen in the well known SESAME format and it derivatives. Herein a different approach is taken, instead using interpolation on an unstructured triangular grid, in short, a UTri table. The UTri format allows optimizing the dominant code path of a physics code, e.g. by tabulating in density-internal energy space, naturally may mesh curved phase boundaries, and easily adapts to meet table accuracy criteria. Examples will demonstrate these benefits with comparison to typical SESAME table usage and the format will be described. |
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