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 J01: Shock to Detonation TransitionFocus Recordings Available
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Chair: Michael Goff, Atomic Weapons Establishment Room: Anaheim Marriott Platinum 5 |
Tuesday, July 12, 2022 11:00AM - 11:30AM |
J01.00001: Mixed explosive gas gun target technique for the study of the shock to detonation transition of insensitive high explosives Invited Speaker: James Ferguson Experimental data on the shock initiation characteristics of high explosives is commonly used for both the calibration and validation of explosive models. Planar impact gas gun experiments provide a repeatable means of generating this data within ‘simple’ one dimensional strain conditions. However, for low sensitivity explosives, the number of guns that can generate a pressure great enough to elicit a reaction in such materials is low. We describe a series of experiments using a mixed explosive target concept whereby the magnitude of the input shock is amplified by the partial completion of the shock to detonation transition in a more sensitive explosive layer before being transmitted into the less sensitive explosive section under study. Through careful selection of an inert intermediatory layer it is possible to transmit chosen complex shocks in the second explosive. This extra layer also separates the second explosive from the energetic products in the first. Data was collected using the embedded, magnetic particle velocity gauge technique and can then be used for the validation of explosive models for the second explosive in the chain. |
Tuesday, July 12, 2022 11:30AM - 11:45AM |
J01.00002: Thin Pulse Experiments Performed Using the TATB-Based Explosives LX-17 and PBX9502 Kevin S Vandersall, Aaron J Ruch, Suzanne M Sheehe, Emily N Weerakkody, Laurence E Fried Experiments were performed to measure the thin pulse shock initiation of the TATB-based explosive formulations, LX-17 and PBX 9502, at ambient temperature to understand the failure threshold. A thin stainless steel flyer plate backed by a low-density foam was used to generate the thin pulse. Impact velocity and flyer thicknesses were varied such that experiments were performed both above and below the transition to detonation threshold. One goal of these experiments was to bridge the data gap between very thin higher velocity "electric gun" experiments and longer sustained-pulse gas gun shock initiation. The experiments provide data for modelling and simulation comparisons, particularly improvements in the regime where TATB-based reaction kinetics may play a role in whether transition or failure is observed. A discussion of this work will include the experimental parameters, data analysis, run-distance-to-detonation or failure characteristics, possible comparisons to modelling and simulation results, as well as suggestions for future experiments. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. |
Tuesday, July 12, 2022 11:45AM - 12:00PM |
J01.00003: Thin pulse experiments performed at -55°C on TATB-based explosives Emily N Weerakkody, Kevin S Vandersall, Aaron J Ruch, Laurence E Fried Experiments were performed at -55°C to measure the thin pulse shock initiation of TATB-based explosive formulations to build on previous experiments at ambient temperature. A thin stainless steel flyer plate backed by a low-density foam was used to generate the thin pulse, and the experiments were performed in a pressure regime where the thin pulse input was high enough to cause a transition to detonation at ambient temperature. This process entailed a redesign of previous hardware utilized to perform similar experiments to minimize material usage and prevent damage to the test chamber, as well as validation of temperature profiles within the target using thermocouples embedded in manganin gauges. Information about temperature-based kinetics of TATB can be gleaned from these tests, and data obtained can be used to inform computational models in development. A discussion of this work will include the experimental parameters, data analysis, run-distance-to-detonation comparisons to prior ambient temperature results, possible comparisons to modelling and simulation results, as well as detail on potential future experiments. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. |
Tuesday, July 12, 2022 12:00PM - 12:15PM |
J01.00004: Ramp Wave Loading of PBX 9501 Michael J Goff, John M Lang, Lee Markland The reactive behaviour of PBX explosives under quasi-isentropic ‘ramp wave’ loading conditions represents a challenge both in experimental generation and hydrocode modelling. A sapphire material graded areal density flyer system was used to ramp load PBX 9501 explosive using a two-stage gas gun; and the reaction of the explosive observed using the particle velocity gauge technique. The experimental data are compared to 3-D hydrocode modelling utilising the CREST reactive burn model. The effect of the ramp loading in comparison to sustained shocks and two shock desensitisation will be discussed. |
Tuesday, July 12, 2022 12:15PM - 12:30PM |
J01.00005: Experimental and Modelling Study of the Effect of Pre-Shock Duration on the Double Shock Initiation Response of PBX 9501 Nicholas J Whitworth, John M Lang, Tariq D Aslam, Matthew A Price, Andrew K Henrick A series of double shock initiation gas-gun experiments have been performed on PBX 9501 (95% weight HMX, 5% binder) in which the input conditions were nominally the same, but the time delay between the two shocks was explicitly varied. The impact conditions generated pre- and main shock pressures of 2.9 and 6.2 GPa respectively, with time delays between them ranging from 0.57 to 1.14 μs. This resulted in different levels of reaction behind the pre-shock prior to the main shock traversing the explosive samples, with the growth of reaction to detonation monitored using embedded particle velocity and shock tracker gauges. Simulated results from three reactive burn models (CREST, AWSD, and SURF) are compared with the measured data to assess their ability to predict the response of PBX 9501 under such double shock conditions. The described experiments add to the body of evidence to help improve our understanding of the double shock initiation response of explosives, and the data obtained provide an excellent test for reactive burn models. |
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