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 K5: BIEP: Ejecta III |
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Chair: Leo Kirsch, LLNL Room: Broadway I/II |
Tuesday, June 18, 2019 2:00PM - 2:30PM |
K5.00001: Studies of reactive and nonreactive metals—ejecta—transporting in nonreactive and reactive gases and vacuum Invited Speaker: William Buttler We report on our studies of reactive and nonreactive metal fragments transporting in reactive and nonreactive gases. We postulate that reactive metal fragments ejected into a reactive gas, such as D$_2$, will break up into smaller fragments in situations where they are otherwise stable in a nonreactive gas such as He. To evaluate the hypothesis, we explosively eject hot, micron-scale fragments into vacuum and shocked gases. We diagnosed the hydrodynamics and the ejecta source with laser Doppler velocimetry, piezoelectric pressure transducers and dynamic Mie scattering. Further, we imaged the ejecta transport at infrared wavelengths and particle imaging velocimetry, discovered an optical scattering diagnostic that revealed dynamic ejecta sheet breakup dynamics, and we applied CARS to shocked D$_2$. This work presents results of the experimental and theoretical studies, but details of important diagnostics are in this conference section. \\ \\ In collaboration with: Jason Cooley, James Hammerberg, Roland Schulze, John Schwarzkopf, Daniel Sheppard, James Barefield, John Charonko, Johnny Goett, Michael Grover, Brandon La Lone, Jason Mance, Ruben Manzanares, John Martinez, Martin Schauer, Derek Schmidt, Gerald Stevens, William Turley, Ruben Valencia [Preview Abstract] |
Tuesday, June 18, 2019 2:30PM - 2:45PM |
K5.00002: Elastic properties of polycrystalline cerium hydrides and deuterides measured using resonant ultrasound spectroscopy Aditya Shivprasad, Tarik Saleh, Joseph Wermer, Roland Schulze, William Buttler During intense shock loading experiments of reactive materials, such as cerium, small fragments are ejected from the roughened metal surfaces. Fragments ejected into hot, reactive gases (i.e. hydrogen or deuterium) may react with the gas and break-up into smaller fragments in cases where they would be otherwise hydrodynamically stable, such as in a non-reactive gas. To study this process, it is important to have high-fidelity measurements of the mechanical properties of reaction products like cerium hydrides and deuterides. However, many reported values for these properties are not self-consistent and are limited to modeling and nano-scale mechanical testing, which requires assumptions about the mechanical behavior. In this study, massively hydrided and deuterided cerium samples were analyzed for room temperature elastic properties using resonant ultrasound spectroscopy, which provides self-consistent, bulk values for elastic moduli. Results are discussed to highlight the differences between the properties of the hydride and the deuteride, as well as to compare results with literature values. [Preview Abstract] |
Tuesday, June 18, 2019 2:45PM - 3:00PM |
K5.00003: Compressible Particle Drag Experiments at Los Alamos National Laboratory Kyle Hughes, Adam Martinez, Ankur Bordoloi, Katherine Prestridge Two series of small-scale experiments have been conducted at Los Alamos National Laboratory examining the compressible drag of particles. First, shock tube experiments individually track 4 $\mu $m nylon particles subjected to mild shocks (Mach 1.1-1.3) using an 8-frame Particle Tracking Velocimetry diagnostic. Results of the particle tracking corroborate model predictions of the C$_{\mathrm{D}}$ during the passage of the shock across the particle at the acoustic time scale, $\tau_{\mathrm{s}}$. However, the unsteady drag coefficient increases by up to an order of magnitude at later times (500 $\tau_{\mathrm{s}})$. The second series of experiments examined the explosive dispersal of 100 $\mu $m steel particles initially closely-packed in a 13 x 6 mm bed with proton radiography. Five explosive tests were performed with each test extracting 21 radiographs at 2 $\mu $s temporal resolution. A vacuum shot was compared to three ambient carrier fluids: air, xenon, and SF$_{\mathrm{6}}$. Centerline upstream and downstream particle fronts extracted from the transmission radiographs demonstrate close agreement, suggesting the shock traversing the bed of particles provides little additional impulse to the dispersed particles in this regime. [Preview Abstract] |
Tuesday, June 18, 2019 3:00PM - 3:15PM |
K5.00004: Measuring the Spatial Evolution of Ejecta Transport Using Particle Image Velocimetry John Charonko, Johnny Goett, Michael Grover, Brandon La Lone, Jason Mance, Ruben Manzanares, John Martinez, Derek Schmidt, Gerald Stevens, William Turley, William Buttler Historically, many diagnostics have been used to examine the production and transport of metal particles from a shocked surface, including x-ray and proton radiography, optical shadowgraphy and imaging, LN-pins, Asay foils, Mie scattering, and PDV. Each measures different quantities such as particle position, size, mass, or velocity. However, direct measurement of the spatial distribution of velocities within ejecta clouds has never before been demonstrated; to do so we report for the first time application of the principles of particle image velocimetry to this problem. Pulsed lasers were used with ultra-high-speed cameras to image light scattered from ejecta, and the images were analyzed to obtain quantitative measurements of the temporally evolving particle velocity fields. We will present results from three dynamic ejecta experiments of Sn transporting in D$_2$ at $P_{initial} = 3040$ torr. For each experiment, the ejecta velocity field within the cloud was sampled at four different times over the first 10 $\mu s$ after shock breakout. The PIV measurements revealed the distribution and variation of speeds between the free surface and observable leading edge of the ejecta cloud. Implications of the work for ejecta dynamics will be discussed. [Preview Abstract] |
Tuesday, June 18, 2019 3:15PM - 3:30PM |
K5.00005: Ejected particle size distributions from shocked Cerium targets Martin Schauer, William Buttler, Michael Grover, Ruben Manzanares, John Martinez, Derek Schmidt, Gerald Stevens, William Turley We report on the results of experiments to constrain the size distributions of particles ejected from shocked Cerium wafer surfaces into vacuum and various pressures of Helium and Deuterium gases by measuring the angular distribution of laser light scattered by the particles. These data are analyzed using the Mie solution to Maxwell's equations and assuming that the particle size distribution function is log normal thereby yielding a continuous record of the size distribution with time, or alternatively with ejected particle velocity, throughout the duration of each experiment.. [Preview Abstract] |
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