Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session V4: ED-4a: Imaging Diagnostics |
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Chair: Michael Furlanetto, Los Alamos National Laboratory Room: Hermitage D |
Thursday, July 2, 2009 1:30PM - 1:45PM |
V4.00001: High resolution experimental measurements of Richtmyer-Meshkov turbulence in fluid layers after reshock Katherine Prestridge, B.J. Balakumar, Gregory Orlicz, Chris Tomkins We present true ensemble-averaged turbulence measurements of density, velocity and density-velocity cross-statistics in a reshocked Richtmyer-Meshkov unstable layer. The experiment is a layer of SF6 embedded in air that is accelerated by a Mach 1.2 shock in a gas shock tube and then reshocked with the reflected shock. Reshock of the gas curtain drives promotes transition to turbulence. We capture instantaneous density and velocity fields simultaneously in two dimensions using Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF). Ensembles of density and velocity fields are collected through repetition of the experiment and close monitoring to ensure identical initial conditions between experiments. Initial conditions of the curtain are perturbed using fixed sinuous and/or varicose nozzles, and the impact of initial condition modes on the resulting turbulence statistics is studied. Data and error analysis, as well as correlation methods, will be presented. [Preview Abstract] |
Thursday, July 2, 2009 1:45PM - 2:00PM |
V4.00002: Digital image correlation applied to shock loading of structural materials Paul Hooper, Hari Arora, Amit Puri, Bamber Blackman, John Dear Shock loading of structural materials is an important design consideration in many civil and military engineering applications. Integrating digital image correlation with high-speed photography has allowed for detailed analysis of high-rate events. This technique has been applied to laminated glass and glass fibre sandwich composite panels loaded by an air blast. A speckle pattern was applied to each panel of approximately 1.8m$^{2}$ and these were photographed at 1,000 frames per second using two high-speed cameras. The analysis has allowed for the measurement of full-field displacements in all three-dimensions and in-plane strains, aiding the verification of material models as well as giving an improved understanding of the failure mechanisms under blast loading. [Preview Abstract] |
Thursday, July 2, 2009 2:00PM - 2:15PM |
V4.00003: Detonator Performance Characterization using Multi-Frame Laser Schlieren Imaging Steven Clarke, Colin Landon, Michael Murphy, Michael Martinez, Thomas Mason, Keith Thomas Multi-frame Laser Schlieren Imaging of shock waves produced by detonators in transparent witness materials can be used to evaluate detonator performance. We use inverse calculations of the 2D propagation of shock waves in the EPIC finite element model computer code to calculate a temporal-spatial-pressure profile on the surface of the detonator that is consistent with the experimental shock waves from the schlieren imaging. Examples of calculated 2D temporal-spatial-pressure profiles from a range of detonator types (EFI --exploding foil initiators, DOI -- direct optical initiation, EBW -- exploding bridge wire, hotwire), detonator HE materials (PETN, HMX, etc), and HE densities. Also pressure interaction profiles from the interaction of multiple shock waves will be shown. LA-UR-09-00909. [Preview Abstract] |
Thursday, July 2, 2009 2:15PM - 2:30PM |
V4.00004: On the Sensitivity of Transient Imaging Displacement Interferometry (TIDI) to Spall Damage Formation Darrin Byler, Scott Greenfield, Davis Tonks, Sheng-Nian Luo, Kenneth McClellan, Aaron Koskelo, Pedro Peralta We seek to develop experimentally-validated models for the microscopic dynamics of void nucleation and coalescence in polycrystalline copper. Our approach uses measurement of the dynamics of the breakout surface during laser-launched flyer experiments registered with specific points in a specimen's microstructure, and post-shot analysis of the shocked specimens. The dynamic measurement diagnostic suite includes TIDI, line- and point- VISARs. The components are spatially registered and time correlated to provide accurate information on the dynamics during the loading and release profile. Fiducials allow correlation with exact positions in the post-shot analysis of the target. TIDI movies of the breakout surface reveal complex dynamics during uniaxial shock loading of polycrystalline copper. Our goal is to extract the details of what occurs at the spall plane during void nucleation and coalescence. To test the diagnostic suite's sensitivity to processes occurring below the breakout surface, we have buried tungsten wires in single crystal copper at various depths and conducted shock loading experiments. This talk will focus on these experiments and code simulations used to study the sensitivity of our instrumentation to spall damage formation. [Preview Abstract] |
Thursday, July 2, 2009 2:30PM - 2:45PM |
V4.00005: Observations of intrinsic shock front anisotropy in diamond P.M. Celliers, D.J. Erskine, D.G. Braun, S.T. Prisbrey, G.W. Collins, R.J. Wallace, O.L. Landen, J. Biener, A.V. Hamza, C. Wild, E. Woerner, A. Nikroo We have fielded a high resolution two-dimensional imaging VISAR at the OMEGA laser facility. Over an 800 $\mu $m field this instrument captures small spatial variations in the velocity across a shock front. The detection limit is \textit{$\delta $V} $\sim $10 m/s giving relative sensitivity \textit{$\delta $V/V} $\sim $ few x 10$^{-4}$, where \textit{V $\sim $ }20 km/s is the shock velocity. The instrument can resolve spatial mode wavelengths as small as 2.5 $\mu $m. We have observed shock front non-uniformities on multi-Mbar shock fronts after passing through polycrystalline diamond. The shock fronts show significant structure at amplitudes below the threshold for shock melting, with a high degree of non-uniformity on spatial scales of a few microns or less. Above the threshold for shock-melting (after the shock front entered the coexistence region, partial melt, near 6 Mbar) the level of non-uniformity diminished significantly. We are continuing experiments on diamond and other materials to elucidate details of the shock front structure above and below the melt transition. [Preview Abstract] |
Thursday, July 2, 2009 2:45PM - 3:00PM |
V4.00006: Proton Radiography at FAIR Frank Merrill, Alexander Golubev, Vladmir Turtikov, Dmitry Varentsov Proton radiography was invented in the 1990's at Los Alamos National Laboratory as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time a proton radiography facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia. Recently an international collaboration was formed to develop a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located at Gesellschaft f\"{u}r Schwerionenforschung (GSI) in Darmstadt, Germany. This new \underline {PR}oton rad\underline {IO}graphy facility at FAI\underline {R} (PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a fundamental understanding of dynamic material properties at new length scales. These dynamic experiments will be driven with many energy sources including heavy ions, high explosives, guns and lasers. The capabilities of this new facility will be presented through a description of the first set of planned experiments. [Preview Abstract] |
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