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 H1: EM-5: Experimental Methods |
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Chair: Steven Son, Purdue University Room: Tennessee Ballroom C |
Tuesday, June 30, 2009 9:00AM - 9:15AM |
H1.00001: Ultrafast X-Ray Phase Contrast Imaging of a Gasless Reactive System Using Third Generation Synchrotron Radiation Robert V. Reeves, Jeremiah D.E. White, Eric M. Dufresne, Kamel Fezzaa, Alexander S. Mukasyan, Steven F. Son, Arvind Varma We report an ultrafast x-ray phase-contrast imaging study of a gasless composite reactive system undergoing high heating rates (10$^{4}$ -- 2.5 x 10$^{5}$ K/s). Construction of an imaging system utilizing a high-speed CMOS camera (Vision Research Phantom v7.3) and the third-generation synchrotron at the Advanced Photon Source at Argonne National Laboratory allows for imaging of microstructural changes of the reactive system over previously unstudied time and length scales. Using Computer-Assisted Electrothermography (CAE), the heating rate of the gasless reactive system Mo-Si is controlled and its kinetics are measured. A physical description of the changes undergone by the system during melting and reaction are captured by the high-speed imaging system and correlated to the recorded CAE data. These changes include microscale nucleated melting and the formation of fluid instabilities. [Preview Abstract] |
Tuesday, June 30, 2009 9:15AM - 9:30AM |
H1.00002: Charged particle motion in an explosively generated ionizing shock C. Boswell, P. O'Connor Several previous studies have investigated the shock generated in a guide tube by an explosive and the ejecta from the explosive and electric and magnetic phenomena associated with it. In these studies the question has arisen, but not satisfactorily answered, as to what is the cause of the wave that travels ahead of the ionizing shock wave. We hypothesize that this wave is an electrostatic pulse, carried by charged particles, created by the photoionization of the gas in the guide tube and the electric field pulse generated when a detonation wave reaches the end of an explosive. Therefore, we studied the motion of charged particles using Rogowski coils and the compressed gas and detonation products behind the shock wave using a time-resolved emission spectroscopy. The shock wave in the gas was generated by an explosive located at one end of a guide tube filled with a gas, typically argon, krypton, or nitrogen. The detonation produced a shock wave strong enough to ionize the gas. Spectral line emission profiles, recorded with a time-resolved emission spectroscopy system, were used to measure temperatures of 7000 K and electron densities of 5 x 10$^{22}$ m$^{-3}$. The Rogowski coils were used to measure a wave of charged particles traveling down the guide tube with a phase velocity of 550 km/s in krypton and 1300 km/s in argon. The results are consistent with the hypothesis that an electrostatic pulse travels down the guide tube, offering a possible explanation for the observed wave. [Preview Abstract] |
Tuesday, June 30, 2009 9:30AM - 9:45AM |
H1.00003: Time Resolved Optical Signatures For Hugoniot State Measurements From Shock Compressed Composition-B Tom Thornhill, Lalit Chhabildas, William Reinhart Broadband photo-diodes sensitive over the visible and near infrared electromagnetic spectrum are used to monitor impact flash luminosity versus time. Based on careful experimental layout and impact timing the prompt portion of the impact flash signatures reveal the shock propagation timing through a Composition-B target plate. Application of Rankine-Hugoniot Jump equations to this waveform timing provides Hugoniot state measurements of shock compressed Composition-B in the 25 to 50 GPa range. This data will be discussed in detail, along with comparison to previous work below the Composition-B detonation pressure. [Preview Abstract] |
Tuesday, June 30, 2009 9:45AM - 10:00AM |
H1.00004: A Simple Line Wave Generator Using Commercial Explosives John Morris, Scott Jackson, Larry Hill A simple and inexpensive explosive line wave generator has been designed using commercial sheet explosive and plane wave lens concepts. The line wave generator is constructed using P1000 and P2000 sheet explosive for the slow and fast components. The design permits the creation of any line width desired. A series of experiments were performed on a 100mm design, measuring the detonation arrival time at the output of the generator using a streak camera. An iterative technique was used to adjust the line wave generator's slow and fast components, and minimize the arrival time deviation. Designs, test results, and concepts for improvements will be discussed. [Preview Abstract] |
Tuesday, June 30, 2009 10:00AM - 10:15AM |
H1.00005: Shock Initiation Experiments on the TATB Based Explosive RX-03-GO with Ignition and Growth Modeling Kevin S. Vandersall, Frank Garcia, Craig M. Tarver Shock initiation experiments on the TATB based explosive RX-03-GO (92.5{\%} TATB, 7.5{\%} Cytop A by weight) were performed to obtain in-situ pressure gauge data, characterize the run-distance-to-detonation behavior, and calculate Ignition and Growth modeling parameters. A 101 mm diameter propellant driven gas gun was utilized to initiate the explosive sample with manganin piezoresistive pressure gauge packages placed between sample slices. The RX-03-GO formulation utilized is similar to that of LX-17 (92.5{\%} TATB, 7.5{\%} Kel-f by weight) with the notable differences of a new binder material and TATB that has been dissolved and recrystallized in order to improve the purity and morphology. The shock sensitivity will be compared with that of prior data on LX-17 and other TATB formulations. Ignition and Growth modeling parameters were obtained with a reasonable fit to the experimental data. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Tuesday, June 30, 2009 10:15AM - 10:30AM |
H1.00006: Simulation of Embedded Electromagnetic Particle Velocity Gauge Package Response in Gas-Gun Experiments Katherine Finn, Nick Whitworth, Caroline Handley In recent years, a comprehensive suite of gas-gun particle velocity gauge experiments have been conducted by Gustavsen et al. A detailed analysis of this data has led to advances in the understanding of the shock to detonation transition in polymer bonded explosives, and hydrocode simulations of the experiments are often used to calibrate reactive-burn models. In these simulations, the gauges are often modeled using Lagrangian marker particles, with no physical representation. In contrast, the experimental gauge package, as developed by Vorthman et al. in the early 1980s, consists of etched aluminium sandwiched between two sheets of FEP Teflon, using an urethane-based glue. The resulting gauge package is approximately 60 micrometres thick and is positioned between two wedge-shaped pieces of explosive at an angle of 30 degrees, to form a right-circular cylinder. This paper investigates whether there is a need to include an accurate representation of the gauge package within future hydrocode simulations. [Preview Abstract] |
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