Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session H3: NT.1 Novel Techniques: PDV |
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Chair: David Chapman, Imperial College London Room: Fifth Avenue |
Tuesday, July 9, 2013 9:15AM - 9:30AM |
H3.00001: Comprehensive Comparison of VISAR and PDV Laser Interferometry in Plane Shock Wave Experiments K.A. Zimmerman, A.J. Iverson, E.P. Daykin, Y. Toyoda, G.D. Stevens, R.S. Hixson, Y.M. Gupta Plate impact experiments, using well-characterized materials, were conducted to achieve a direct and comprehensive comparison of two laser interferometry approaches used to measure shock wave profiles: Velocity Interferometer System for Any Reflector (VISAR) and Photon Doppler Velocimetry (PDV). A unique feature of this study was a one-to-one comparison of the two measurement approaches in each experiment. A broad range of stresses (4-60 GPa) were examined in this study. The choice of impactor and target materials permitted us to examine different types of material responses (elastic, elastic-plastic, and time-dependent elastic-plastic deformation) which, in turn, resulted in different types of wave profiles (single wave, two-wave structure, and two-wave structure with rapid stress relaxation following the first wave). Overall, the two approaches showed good agreement. However, small but discernible differences were observed in the following situations: wave profiles involving rapid stress relaxation behind the elastic wave; and window-corrected, peak states at high stress. The relative strengths and weaknesses of both methods are summarized. Work supported by DOE/NNSA. [Preview Abstract] |
Tuesday, July 9, 2013 9:30AM - 9:45AM |
H3.00002: PDV experiments on size-calibrated particles accelerated using a pulsed laser Patrick Mercier, Gabriel Prudhomme, Laurent Berthe, Jacky Benier, Pierre-Antoine Frugier In order to observe a particle cloud produced at the output face of a shock-loaded plate, we performed several experiments with size-calibrated particles deposited on an Aluminum plate. It was shock-loaded using a pulsed laser (1 J, 10 ns, 532 nm) resulting in an acceleration of the particles up to 100 m/s. Various experiments have been performed to study the influence of different parameters: the particle material (Cu, Al, Au), the particle diameter (a few micrometers), the thickness of the deposited particle layer and the shock pressure. We recorded the back-reflected light with both orthogonal and tilted probes, and we present the corresponding PDV spectrograms displaying cloud velocities as well as velocity tracks due to individual particles. Some of them decelerate within the ambient gas while others, non-spherical, also rotate. By applying a deceleration model, we were able to determine the initial particle velocities and their sizes. The obtained sizes are consistent with the manufacturer values. In addition, the tilted probes could be used to infer information on the shape of the moving particle clouds. [Preview Abstract] |
Tuesday, July 9, 2013 9:45AM - 10:15AM |
H3.00003: New developments in PDV Invited Speaker: Erik Moro Photon Doppler velocimetry (PDV) has made the transition among many experimental groups from being a new diagnostic to being routinely fielded as a means of obtaining velocity data in high-speed test applications. Indeed, research groups both within and outside of the shock physics community have taken note of PDV's robust, high-performance measurement capabilities. As PDV serves as the primary diagnostic in an increasing number of experiments, it will continue to find new applications and enable the measurement of previously un-measurable phenomena. This paper provides a survey of recent developments in PDV system design and feature extraction as well as a discussion of new applications for PDV. More specifically, changes at the system level have enabled the collection of data sets that are far richer than those previously attainable in terms of spatial and temporal coverage as well as improvements over PDV's previously measurable velocity ranges. And until recently, PDV data have been analyzed almost exclusively in the frequency-domain; although the use of additional data analysis techniques is beginning to show promise, particularly as it pertains to extracting information from a PDV signal about surface motion that is not along the beam's axis. [Preview Abstract] |
Tuesday, July 9, 2013 10:15AM - 10:30AM |
H3.00004: PDV experiments on shock-loaded particles Gabriel Prudhomme, Patrick Mercier, Laurent Berthe, Davina Sihachakr, Christian Rion We present results from PDV experiments in which particles are ejected from shock-loaded metallic plates. The shocks in the samples were generated using either a pulsed laser or high-explosive plane-wave generators. In a first series of experiments, we deposited size-calibrated particles (around 10-$\mu$m in diameter) on the target surface. We analyzed the back-reflected light to infer the free surface and particle velocities (up to several km/s), as well as the cloud structure, as a function of the variable parameters: the particle material (tin, copper, gold, etc.), the particle diameters (a few microns) and the thicknesses of the deposited particle layer. In the second series of experiments, we observed the particles created by microjetting, microspalling or melting at the free surface of tin plates. The slowing down of the particles in air has been measured and, in some experiments, the interaction of secondary shockwave with the particle cloud has also been observed. Finally, we compare these results to those obtained with simple models and with a hydrodynamic code (H\'{e}sione). [Preview Abstract] |
Tuesday, July 9, 2013 10:30AM - 10:45AM |
H3.00005: 3D Hemispherical Test Development to Evaluate Detonation Wave Breakout Elizabeth Francois, John Morris, Mark Lieber, Larry Hill The onionskin test has been the standard test to evaluate detonation wave breakout over a hemispherical surface for decades. It is not without it's shortfalls however. It only images a small portion of the explosive and requires very precise alignment and camera requirements to make sense of the results. Asymmetry in explosive behavior cannot be pinpointed or evaluated effectively. We have developed a new diagnostic using fiber optics covering the surface of the explosive to yield a 3D representation of the detonation wave behavior. Precise timing mapping of the detonation over the hemispherical surface is generated which can be converted to detonation wave breakout behavior using Huygens's wave reconstruction. This presentation and paper will include the results of a recent suite of tests. The results of these tests will describe the effects on detonation wave breakout symmetry when inert materials are placed between the detonator and booster. The value of this test in visual representation of dynamic behavior will be presented and discussed. Statistical analysis of the test as compared to the onionskin test will be outlined. Test limitations and future improvements will be discussed. [Preview Abstract] |
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