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 T4: MS: Materials Science I |
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Chair: Brian Jensen, LANL Room: Pavilion West |
Thursday, June 20, 2019 2:00PM - 2:30PM |
T4.00001: Thermal Conductivity Measurement at Static High Pressure and Dynamic High Temperature Invited Speaker: Ryan Stewart McWilliams The laboratory measurement of thermal transport dynamics at extreme conditions of pressure and temperature has been traditionally challenging. Combining static compression in a diamond anvil cell with dynamic laser heating and temperature measurement has shown promise at providing these essential data. Tracking of propagating temperature disturbances in heated, compressed samples allows direct analysis of the thermal conduction and diffusion coefficients at relevant extremes. I will discuss results for metals Fe, Pt, and Mo for which there is extensive existing experimental and theoretical study at high pressure and temperature for comparison. The importance of benchmarking studies on simple, well understood materials, and the need for careful experimental modelling, is discussed in the context of persistent disagreement over the thermal conductivity of Fe at conditions relevant to Earth's core, with direct measurements, estimates based on electrical resistivity data, and first principles calculation often yielding inconsistent values. Recent measurements, of both thermal and electrical transport, are examined using detailed finite element models of experiments to assess sources of systematic error and develop strategies for improving measurements. [Preview Abstract] |
Thursday, June 20, 2019 2:30PM - 2:45PM |
T4.00002: Sound Velocity in Shocked Iron, Copper, and Beryllium to ~1500 GPa Margaret Huff, Linda Crandall, Ryan Rygg, Brian Henderson, Mohamed Zaghoo, Gilbert Collins, Chad McCoy, Dayne Fratanduono, Peter Celliers, John Eggert 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 \textasciitilde 400~to 1500 GPa, as well as sound speeds in high-pressure beryllium and copper. A novel, nonsteady wave-analysis technique\footnote{ D. E. Fratanduono \textit{et al.}, J. Appl. Phys. \textbf{116}, 033517 (2014).} allows us to infer sound speed from the relative arrival times of pressure perturbations that transited the shocked sample material 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-NA0003856, the University of Rochester, and the New York State Energy Research and Development Authority. [Preview Abstract] |
Thursday, June 20, 2019 2:45PM - 3:00PM |
T4.00003: Dynamic Longitudinal Sound Velocity Measurements in Lead Mark Collinson Measurement of a materials longitudinal sound velocity at pressure can yield new information on its equation of state and strength. This includes sensitivity to phase changes, such as the face centred cubic - hexagonal close packed (FCC -- HCP) transition seen at 14 GPa in existing diamond anvil cell studies on lead. Results are presented on a series of gas gun driven plate impact experiments at stresses between 5 and 17 GPa, focussed on the dynamic measurement of the longitudinal sound velocity. Thin tungsten flyer plates were used to generate a shock and release profile, with arrival times of both the shock and initial rarefaction waves measured using frequency shifted PDV at multiple sample thicknesses via a stepped target setup. A comparison of these experimental results to current multi-phase material models are presented, with a reduced gradient in the sound velocity with pressure observed compared to that predicted. Initial results on the dilute lead antimony alloy are also presented, facilitating comparison with the pure lead material. [Preview Abstract] |
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