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 C01: Detonation Intermediates and ProductsFocus Recordings Available
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Chair: Michael Powell, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 5 |
Monday, July 11, 2022 11:00AM - 11:15AM |
C01.00001: The Trinity High Explosive Implosion System: The Foundation for Precision Explosive Applications Eric N Brown, Dan L Borovina This article is set during the 1944 and 1945 final push to complete Project Y—the Manhattan Project at Los Alamos—and focuses primarily on overcoming the challenge of creating and demonstrating a successful convergent explosive implosion to turn a subcritical quantity of plutonium into a critical mass. The critical mass would then efficiently yield kilotons of trinitrotoluene (TNT)-equivalent energy in about a microsecond, demonstrating the implosion atomic bomb concept. This work culminated in the Trinity atomic test near Alamogordo on July 16, 1945. This implosion effect demarcated the approach to explosive science and technology the Laboratory has followed ever since, including development of high-explosive synthesis and formulation, small and large test and diagnostic facilities, shock dynamics theory, high-explosive system design engineering, and three-dimensional implosion modeling and simulation using some of the fastest computers in the world. This work also ushered in a period of broader application of precision high explosives in conventional munitions, demolition, mining and oil exploration, and space travel. |
Monday, July 11, 2022 11:15AM - 11:45AM |
C01.00002: Temperature measurement and intermediate emitting species identification in deflagrating PBX 9502 reaction zones using visible emission Invited Speaker: Suzanne M Sheehe The reaction kinetic pathways for the decomposition of 1,3,5,-triamino-2,4,6-trinitrobenzene (TATB) in detonating conditions are not fully understood. Current models use only a 1- or 2-step reaction mechanism, which may not encompass relevant kinetic effects on detonative performance. There is a need for data on transient species that can be used to develop, validate, and improve multi-step reaction models. Spectroscopic interrogation of the reaction zone in detonating conditions is challenging due to high optical capacity, spatially and temporally short scales ( <100 ns and < 500 microns). Deflagrations are temporally and spatially stretched (mm/s) by comparison and with lower optical opacities. This readily enables optical diagnostics to generate data to develop mechanisms that can be extrapolated to detonating conditions. Here, we study the decomposition of TATB in its PBX 9502 formulation (95% wt TATB and 5% wt Kel-F-800) when deflagrating at 100 bar in an argon atmosphere. The burn rates for five separate tests were measured and are found to be consistent with prior measurement. Emission spectroscopy is used to infer temperature and validated using a non-optical technique. A MatLab script automated the identification and analysis of transient species across the hundreds of spectra that were collected over five separate tests. The analysis incorporated correlation functions to find related peaks and trends across all tests. Highly correlated peaks were found to match known species. These species and their spectra will be discussed in detail. |
Monday, July 11, 2022 11:45AM - 12:00PM |
C01.00003: Kinetics of Carbon Condensation in Detonation of High Explosives: First-Order Phase Transition Theory Perspective Kirill A Velizhanin, Apoorva Purohit The kinetics of carbon condensation, or carbon clustering, in detonation of carbon-rich high explosives is modeled by solving a system of rate equations for concentrations of carbon particles. Unlike previous efforts, the adopted rate equations account not only for the aggregation of particles, but also for their fragmentation in a thermodynamically consistent manner. Numerical simulations are performed, yielding the distribution of particle concentrations as a function of time. In addition to that, analytical expressions are obtained for all the distinct steps and regimes of the condensation kinetics, which facilitates the analysis of the numerical results and allows one to study the sensitivity of the kinetic behavior to the variation of system parameters. The latter is important because the numerical values of many parameters are not reliably known at present. Such physical phenomena and regimes of carbon condensation as the coagulation, nucleation, growth, and Ostwald ripening, and their dependence on various parameters of detonation will be discussed. |
Monday, July 11, 2022 12:00PM - 12:15PM |
C01.00004: 3-Component reactive flow modeling of Nitromethane Vincent R Schuetz, Donald S Stewart We present a 3-component reactive flow model for nitromethane (NM) as an improvement upon the 2-component global chemical reaction kinetics to describe the detonation reaction zone behind the shock front. A 2-component model, in this case, is the representation of unreacted raw explosive transitioning to final products using a single reaction progress variable. The groundwork of the approach was laid out in a previous publication ( Stewart, J. Appl. Phys. 2016), but implementation of the model was never formalized. Molecular dynamics experiments and simulations on nitromethane from that of Blais et al(J. Phys Chem, 1997) and the Goddard group (J. Phys Chem, 2011) agree that an unstable heavy condensate is created shortly after shock passage which then decomposes exothermically into final products. Where a 2-component model can only add energy to the flow as reactants decompose, a 3-component model with an included endothermic reaction step can both add and subtract energy, depending upon the component mass fraction gradients. With the addition of an intermediate component, we intend to show a more proper understanding of phenomena such as the shock initiation of nitromethane. Modern gas gun experiments that propel a right circular disk impactor, and laser-ablation-product launched flyer experiments (Dlott, AIP Confer. Proc., 2015) have been used extensively on nitromethane. We intend to use this data set to compare our 3-component reactive flow model and 2-component models for accuracy and validity of shock initiation prediction. |
Monday, July 11, 2022 12:15PM - 12:30PM |
C01.00005: Multimodal Characterization of Recovered Detonation Soots Mike H Nielsen, Joshua A Hammons, Michael Bagge-Hansen, Lisa M Lauderbach, Shaul Aloni, Sorin Bastea, Laurence E Fried, Trevor M Willey Nanodiamond and other carbon allotropes are pervasive throughout the solid residue produced by the detonation of many common high explosive materials, with the specific composition depending on many factors including the initial chemistry and detonation environment. Detonation models predict which allotropes may form, but experimental validation is necessary. Synchrotron-based, ultrafast measurements provide insight into early events in carbon condensation from detonating high explosives. However, data interpretation is often difficult absent additional information about the nature of the nanoscopic constituents of the produced soot. Detonating similar explosive charges and capturing the early particulates in ice allows for clean (minimal environmental carbon) recovery and mitigates potential changes induced by prolonged particulate burn in air. Transmission electron microscopy, x-ray spectroscopies, and other methods yield insight into the morphology, phase, chemistry, and elemental composition of the recovered carbonaceous soots. We use the well-researched Composition B (40% TNT and 60% RDX) as a reference point, and present comparative data from explosives such as HNS, DNTF, TATB-based formulations, and others, to show trends in carbon allotrope, morphology, and elemental composition of the condensate in relation to the initial chemistry and calculated position of the Chapman-Jouget point and subsequent evolution through the carbon phase diagram. |
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