Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session O01: Flyer and Detonator InitiationFocus Recordings Available
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Chair: Belinda Johnson Room: Anaheim Marriott Platinum 5 |
Wednesday, July 13, 2022 9:15AM - 9:30AM |
O01.00001: Exponential initiation function and flyer optimization yasuyuki horie, David L Damm There are two commonly used criteria for describing the shock initiation threshold of high explosives. They are Walker and Wasley, and James criteria that are based on the value of energy flux or a hyperbolic function of energy flux and kinetic energy, respectively. A recent addition is the use of an exponential function1,2 that is based on energy and power fluxes. This paper explores possible merits and use of the new exponential function and its scaling parameters. When combined with the James observation on the relation between the initiation threshold and Pop-plot, the scaling parameter reduces to an equation that can be analytically inspected for the existence of a domain where a parallel shifting of the two thresholds is a good approximation. We then considered, following the approach discussed by Horie et al.3, the use of the new parameter to determine the optimum flyer property that generates the ‘best’ impact to deliver energy into the target. The resulting equation is a transcendental equation that does not allow a simple analytic solution, but in the case of bounding situations such as a sustained load, it yields a simple closed form solution for the optimum choice of flyer shock impedance relative to that of the target. Additional implication of the equation for the optimized impact velocity is the existence of the minimum shock duration, indicating that thin pulse (un-sustained shock) may not be amenable to the optimization depending on its duration. |
Wednesday, July 13, 2022 9:30AM - 9:45AM |
O01.00002: A TNT burn model Christopher C Ticknor, Stephen A Andrews, Jeffrey H Peterson, Jeffrey A Leiding, Tariq D Aslam This work describes the calibration of the Arrhenius Wescott-Stewart-Davis (AWSD) reactive flow model for TNT. We discuss the data used to make the calibration and look at several different choices we made in the modeling. We review the resulting reactant and product equation of state. For the rate law calibration, we use shock to detonation transition and diameter effect experiments. |
Wednesday, July 13, 2022 9:45AM - 10:15AM |
O01.00003: Laser slapper detonator for shock compression study of energetic materials Invited Speaker: Philippe HEBERT We have developed a tabletop experimental setup for the study of shock compression of energetic materials. Shocks are generated using metallic flyer plates driven by a slapper detonator. The detonator is initiated using Aluminum laser-driven flyer plates launched by a compact commercial Nd:YAG laser. Our setup offers a wide variety of shock conditions with flyer thicknesses ranging from 10 to 500 mm and velocities of up to 5 km/s, depending on the flyer material used. Typical shock pressures of up to 50 GPa and shock durations of up to 200 ns can be achieved. The flyer diameter can also be varied between 0.7 and 4 mm. Different diagnostics are available to characterize flyers and shocked materials. They include photon Doppler velocimetry (PDV), streak and high-speed framing cameras, absorption and single-shot Raman spectroscopy. In this paper, we will describe in detail our free space laser slapper detonator. Then, we will present three applications of our shock generator: (1) High-Pressure inert Hugoniot measurement of T2 TATB-based explosive; (2) Temperature measurement of shocked T2 by Raman spectroscopy; (3) Initiation study of pressed powdered LLM-105. Finally, we will present the fiber version of our laser detonator, which can easily be used to trigger detonation experiments. |
Wednesday, July 13, 2022 10:15AM - 10:30AM |
O01.00004: Exploding Bridgewire Detonator and Arc Initiation Detonator Comparison Laura Smilowitz, Bryan F Henson, Dennis Remelius We have studied the function of both standard exploding bridgewire (EBW) and modified arc initiation detonators in order to understand how the input to the initial pressing explosive powder (IP) leads to detonation. Standard EBW detonators function with a bridgewire which is heated rapidly through melt/vaporization. The initiation of detonation in the surrounding low density explosive powder of the IP has been attributed to both shock and thermal pathways. In this study, we compare the function of EBW detonators with bridgewires to a modified design where the bridgewire does not present a continuous circuit. Without this wire, the application of power to the pins causes an arc across the pins when sufficient voltage is applied. This arc then initiates detonation in the IP. The comparison of observables including voltage, current flow, light emission, density, and temperature between the bridgewire detonators and the bridgeless arc initiated detonators teaches us about function of both. Results of both studies will be described and lessons learned from the comparison discussed. |
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