Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session T2: Detonations and Shock-Induced Chemistry VI |
Hide Abstracts |
Chair: Mike Armstrong, Lawrence Livermore National Laboratory Room: Grand Ballroom IV-V |
Thursday, June 30, 2011 11:00AM - 11:15AM |
T2.00001: Multiscale Simulation of Hot Spot Ignition Laurence Fried, Fady Najjar, W. Michael Howard, M. Riad Manaa, Sorin Bastea High explosive shock sensitivity is controlled by a combination of mechanical response, thermal properties, and chemical properties. How these properties interplay in realistic condensed energetic materials is not well understood. In this paper, we use a multiscale approach to achieve a realistic simulation of hot spot (void) ignition in a single crystal of the explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The smallest length scale (< 10 nm) of the multiscale model was treated quantum mechanically. We have conducted multiple simulations of the decomposition of the explosive TATB using density functional tight binding molecular dynamics (DFTB-MD). Nanoscale continuum simulations were performed of void ignition using the ALE3D hydrodynamic/thermal/chemical code. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, June 30, 2011 11:15AM - 11:30AM |
T2.00002: Determination of detonation parameters for liquid High Explosives Valentina Mochalova, Alexander Utkin The experimental investigation of detonation parameters and reaction zone structure in liquid HE (bis-(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), nitromethane (NM)) was conducted. Detonation front in TNM and NM was stable while the instability of detonation in FEFO was observed. Von Neumann spike was recorded for these HE and its parameters were determined. The different methods for C-J point determination were used for each HE. For FEFO reaction time $\tau $ was found from experiments with different charge diameters ($\tau $ is approximately equal to 300 ns); for TNM -- at fixed diameter and different lengths of charges ($\tau \quad \approx $ 200 ns); for NM -- at fixed diameter and length of charges, but detonation initiation was carried out by different explosive charges ($\tau \quad \approx $ 50 ns). It was found that in TNM the detonation velocity depends on charge diameter. Maximum value of reaction rate in investigated liquid HE was observed after shock jump and induction time was not recorded. [Preview Abstract] |
Thursday, June 30, 2011 11:30AM - 12:00PM |
T2.00003: Shocked reactions: the first half nanosecond Invited Speaker: Ultrafast laser techniques allow resolution of shock induced physics and chemistry picoseconds behind the shock front. We combine 300 ps sustained laser-generated shocks with ultrafast dynamic ellipsometry to measure the shock state and transient absorption to measure the molecular electronic response to shock loading. Additional nonlinear spectroscopic probes offer the potential to measure even more details of the molecular shock response, such as vibrational temperature and evolution of chemical species. Experimental data will be presented on shocked explosive crystals and liquids. Explosive crystals are studied for the relevance to shock initiation processes. A range of simple molecular liquids is being studied to map out shock reactivity as a function of systematic variations in bonding. The relation of the ultrafast laser data to molecular dynamics simulations and large scale gas gun work will be discussed with an emphasis on what the synthesized information can tell us about shock induced chemical reactions across this broad range of length and time scales. [Preview Abstract] |
Thursday, June 30, 2011 12:00PM - 12:15PM |
T2.00004: Photoexcitation, Reaction Localization and Energy Dissipation in Single beta-HMX Crystals subjected to 20 GPa Shock and PBX Detonation Igor Plaksin, L. Rodrigues, S. Plaksin, R. Mendes, J. Campos, P. Simoes We present experimentally revealed highly anisotropic dynamics of the detonation conversion occurring in beta-HMX crystals. Panoramic observation of 1-mm single b-HMX crystal surrounded by different binder materials (HTPB, GAP, water) and by fine-grained PBX (HMX 85/15 GAP as a dirty binder) performed by mean of Multi-Channel Optical Analyzer (96 optical fibers) provided spatially resolved measurements of reaction spots onset/growth and a post-detonation ejecta of reaction products via the radiance registration carried out with 100$\mu $m-spatial and 0.2ns-temporal accuracy in a spectral range 450-850nm. Experimental evidences obtained in more than 20 tests with b-HMX crystals subjected to a 20GPa shock and to the PBX detonation (51GPa-VN spike at entering to a crystal and 21.5GPa-CJ pressure), demonstrate that independently on orientation crystal vs. input front, a major reaction spots are localized in crystal vertexes/edges and the emitted reaction radiance induces photoexcitation in the crystal bulk causing a radiation-induced precursor of the major reaction front. Further reaction spots dissipation is attended by origination of the reaction products' longitudinal/transversal ejecta moving behind the leading front with the 20-30 micron/ns speed. [Preview Abstract] |
Thursday, June 30, 2011 12:15PM - 12:30PM |
T2.00005: Ultrafast Shock Interrogation of Hydrogen Peroxide/Water Mixtures: Thermochemical Predictions of Shock Condition Chemistry Joseph Zaug, Michael Armstrong, Sorin Bastea, I.-F. William Kuo, Jonathan Crowhurst, Michaela Kashgarian Hydrogen peroxide is a powerful oxidizer and its concentrated aqueous solutions exhibit very high reactivity, even sustaining detonation under strong enough confinement. Due to its simple composition and basic expected decomposition kinetics hydrogen peroxide is very suitable for studying the interplay of high pressures, temperatures and reactivity and their effect on the equation of state, particularly at the boundary between detonating and non-detonating behavior. To this end we have performed picosecond time resolved shock measurements on solutions of hydrogen peroxide of concentrations from 30 to 90 percent, and analyzed the results in terms of common assumptions of chemical equilibrium in reactive fluid mixtures. Experimental shock states were achieved up to a maximum pressure of 20 GPa with corresponding shock velocities of 6-7 km/sec. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700