Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session Q4: Experimental Developments IV |
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Chair: Rick Gustavsen, Cambridge University Room: Fairmont Orchid Hotel Plaza II |
Thursday, June 28, 2007 1:45PM - 2:00PM |
Q4.00001: 3D Simulation Capability for Isentropic Compression Loads S. Chantrenne, T. Ao, J.R. Asay, T.A. Haill, H.L. Hanshaw, C.A. Hall For the past 10 years, equation-of-state experiments have been carried out using magnetic pressure to isentropically compress materials. Recently, a compact, fast strip-line pulser was designed with the objective of doing isentropic compression experiments at low cost, with rapid turn around, with good shot-to-shot reproducibility, and with the ability to shape the current profile for the material being tested. In this work, we present the results of 3D simulations of isentropic compression loads that were performed with Sandia National Laboratories' ALEGRA MHD code. In order to understand the pressure magnitude and uniformity, current density distributions were calculated from the capacitors to the load. Free-surface velocity measurements are compared to those obtained from these simulations and show reasonable agreement. Details describing the computational methods used in these simulations will be discussed. [Preview Abstract] |
Thursday, June 28, 2007 2:00PM - 2:15PM |
Q4.00002: Development of a Single Stage Implosion-Driven Hypervelocity Launcher Daniel Szirti, Jason Loiseau, Patrick Batchelor, Andrew Higgins, Vincent Tanguay, Fan Zhang Work carried out on the development of a single stage implosion-driven hypervelocity launcher is presented. Explosives surrounding a thin-walled tube filled with helium works similar to the pump tube of a conventional light gas gun. Implosion of the tube drives a strong shock that reflects back and forth between the projectile and the implosion pinch, generating very high temperatures and pressures. Experiments to evaluate the implosion dynamics and performance of the pump tube were carried out, with attention given to the helium fill pressure, diameter of the pump tube, thickness of the explosive layer, and the presence of a tamper. Simple analytic models were used to approximate the performance of the launcher; their advantages and limitations are discussed. Experiments with an implosion-driven launcher demonstrated muzzle velocities of 4 km/s with 4-mm-diameter aluminum projectiles, giving good agreement with the analytical models of performance. Projectile integrity was verified by high-speed photography and other diagnostics. [Preview Abstract] |
Thursday, June 28, 2007 2:15PM - 2:30PM |
Q4.00003: Modeling of an Implosion Driven Hypervelocity Launcher Jason Loiseau, Andrew Higgins, Daniel Szirti, Patrick Batchelor, Fan Zhang, Vincent Tanguay Modelling work carried out on the implosion driven launcher under concurrent development is presented. The launcher consists of a thin walled metal tube surrounded by explosive which when detonated pinches the tube shut and drives a strong shock into the projectile. The commercial hydrocode LS-DYNA was used to quantitatively and qualitatively evaluate the design parameters of the launcher and their effect on implosion dynamics and performance. These parameters include fill pressure, tube diameter, explosive layer thickness, and explosives tampering. The launcher is primarily modeled using a quasi 2D Arbitrary Langrage Euler formulation. A full 3-D axisymmetric model is also employed. The model is evaluated against experimental data previously collected. Additional developmental work on a second stage launcher taking advantage of a phase velocity between the imploding tube and explosives via the use of angled flyer plates and cones is also carried out. [Preview Abstract] |
Thursday, June 28, 2007 2:30PM - 2:45PM |
Q4.00004: Characterisation and Modification of Thermally Stable High Explosives for Laser Flyer Applications Adam Parker, Robert Claridge, William Proud Laser initiation offers improved weapon survivability, versatility and greater IM compliance. Detonators based on laser-driven flyers are less vulnerable to electrical initiation, and can be based on insensitive secondary explosives rather than sensitive primary explosives. Additionally, this technology will offer advantages in terms of improved flexibility and reliability. Several novel energetic materials were selected for investigation at QinetiQ. The materials are of interest due to their increased thermal stability and power output over conventional explosives. These properties promote the materials as ideal candidates for use in insensitive munition compliant applications, whilst also improving performance. The response of these materials to short duration high-amplitude shock impulses by laser-driven flyers was investigated. Preparation techniques including co-crystallisation, sonication and incorporation of additives were used to sensitise the materials to flyer impact, yet maintain their insensitivity to external hazards. Hazard characterisation was performed to ensure that no detrimental effects were caused by modification. [Preview Abstract] |
Thursday, June 28, 2007 2:45PM - 3:00PM |
Q4.00005: ABSTRACT WITHDRAWN |
Thursday, June 28, 2007 3:00PM - 3:15PM |
Q4.00006: Performance and operational characteristics of the WSU compact pulser power machine for shockless compression T. Jaglinski, C.J. Bakeman, J.R. Asay, J. LaFollett, K. Zimmerman, Y.M. Gupta A compact pulsed power machine (CPPM) is now operational at the Institute for Shock Physics. Development of this capability, to carry out shockless compression, was closely coordinated with similar developments at Sandia Laboratories. In preparation for dynamic material property experiments, the performance and operational aspects of the CPPM were characterized by considering two panel materials (aluminum and copper), two panel widths (15 mm and 20 mm) utilizing the Sandia design, and two charging voltages (65 and 70 kV). Free surface velocities were monitored to determine the input pulse into the samples of interest. Results from these experiments have provided an envelope of peak stresses and rise times that can be obtained using the present configuration of the CPPM. Results regarding uniformity and wave shapes will be presented. Work supported by ONR and DOE. Discussions with colleagues at Sandia National Laboratories are acknowledged. [Preview Abstract] |
Thursday, June 28, 2007 3:15PM - 3:30PM |
Q4.00007: High-Pressure Quasi-Isentropic Loading and Unloading of Interferometer Windows on the Veloce Pulsed Power Generator Tommy Ao, James Asay, Marcus Knudson, Jean-Paul Davis The Isentropic Compression Experiment technique has proven to be a valuable complement to the well-established method of shock compression of condensed matter. However, whereas the high-pressure compression response of window materials has been studied extensively under shock loading, similar knowledge of these materials under ICE loading is limited. We present recent experimental results on the isentropic compression of the high-pressure windows sapphire and LiF. It has previously been observed that c-cut sapphire yields under shock loading at the HEL of $\sim $15-18GPa, and subsequently loses transparency at higher stresses. However, it will be shown that under isentropic ramp wave loading sapphire appears to remain elastic and transparent at stresses well above 20GPa [D.B. Hayes et al, JAP 94, 2331 (2003)]. LiF is another frequently used window material in isentropic loading and unloading experiments, yet the unloading response of LiF is usually neglected. Research is in progress to measure strength properties of LiF for ramp loading and unloading. It will be shown how the strength of LiF may influence wave profile analysis and thus inferred material strength. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the US DOE's NNSA under Contract No.DE-AC04-94AL85000. [Preview Abstract] |
Thursday, June 28, 2007 3:30PM - 3:45PM |
Q4.00008: Magnetically Driven Isentropic Compression and Flyer Plate Experiments Using A Compact Capacitor Bank. Chengwei Sun, Guiji Wang, Cangli Liu, Jianheng Zhao, Fuli Tan, Ning Zhang, Jun Chen The pulsed power generator CQ-1.5 is a compact capacitor bank of total capacitance 15.88 $\mu $F, maximum energy stored 50.8 kJ and normal discharging current 1.5MA in 500ns on a 2$\sim $3nH inductive load. This low cost generator has been developed by the Institute of Fluid Physics, and is motivated for isentropic compression experiments(ICE) up to 30$\sim $50GPa and flyer plate launching at velocity 5$\sim $7 km/s. It is characterized by low inductance ($\sim $ 18nH) attributed to the specially designed capacitor, the explosive network closing switch and the compact plate transmission line. The design and experiments of ICE specimens and flyers are described here. The measured free surface velocities of two ICE specimens of different thickness were treated by backward integration to acquire the compression isentrope of copper up to 50GPa. An energy conservation based model to predict the performance of magnetically driven flyers has been proposed and compared with the experimental data measured by VISAR interferometer. [Preview Abstract] |
Thursday, June 28, 2007 3:45PM - 4:00PM |
Q4.00009: A new experimental design for laser-driven shocks on precompressed and preheated water samples. Arnaud Sollier, Eric Auroux, Jean-S\'ebastien Vauthier, Michel Boustie, Hongliang He, Thibaut de Ress\'eguier, Patrick Berterretche, Nicolas Desbiens, Emeric Bourasseau, Jean-Bernard Maillet High energy lasers are now widely used to study the dynamic properties of matter up to very high pressures. Generally, such experiments employ a sample initially at normal density and standard pressure, therefore providing data on the principal Hugoniot. In this work, a special vessel has been used to statically compress and pre-heat water samples up to about 300 bar and 300$^{\circ}$C, before they were shocked with an energetic laser. This configuration allows to reach states lying above the water Hugoniot in the temperature-pressure diagram, which are representative of the thermodynamic parameters of water in the detonation products of high explosives. We describe the method to achieve off principal Hugoniot data and report the first experiments which were performed on the LCD's laser system at low shock pressure (2 GPa). The results are compared with the Sesame tables and with Monte Carlo calculations performed using a TIP4P potential. [Preview Abstract] |
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