Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session S3: Experimental Developments VI: NanoCarbons and X-ray Scattering |
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Chair: Mike Armstrong, Lawrence Livermore National Laboratory Room: Grand Ballroom FG |
Thursday, July 13, 2017 9:15AM - 9:45AM |
S3.00001: Unveiling formation mechanisms for hierarchical nanocarbons derived from the detonation of high explosives Invited Speaker: Millicent Firestone The direct evaluation of chemical reactions that ensue behind the shock front is challenging, and as a result details of the nucleation and growth of solid carbon products remain poorly described. To improve our understanding of carbon fragment evolution post detonation of high explosives a combination of post-mortem analysis of the recovered soot and \textit{in-situ} characterization of the carbon particles have been conducted. Primary particle morphology and distribution of carbon hybridization states are evaluated though multi-scale diagnostic characterization on unfractionated, unpurified recovered soot. The solid carbon condensates vary significantly depending on the high explosive and / or the detonation conditions. Based upon careful post-mortem analysis of the carbon particles recovered formation mechanisms are postulated in the context of detonation conditions. Mechanism verification is carried out, in part, by operando time-resolved X-ray scattering that probes the evolution of the carbon condensates behind the shock front on the hundreds of nanosecond to microsecond time regime. Understanding the correlation between detonation conditions and carbon product formation is important for achieving greater accuracy in predicting high explosive performance and model refinement. [Preview Abstract] |
Thursday, July 13, 2017 9:45AM - 10:00AM |
S3.00002: Dynamic Compression Sector: Time-Resolved Synchrotron X-Ray Measurements in Shock Wave Experiments P. A. Rigg, N. Arganbright, J. Klug, C. Konrad, Y. Li, D. Rickerson, A. Schuman, J. Sethian, N. Sinclair, Y. Toyoda, S. Turneaure, B. Williams, E. Zdanowicz, K. Zimmerman, Y. M. Gupta The Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS) located at Argonne National Laboratory -- a first-of-its-kind user facility -- has been established to address long standing scientific questions regarding atomistic -- and micro/meso -- scale mechanisms governing condensed matter changes under high stress, dynamic loading. By linking a diverse set of dynamic compression drivers to $\sim$80ps bright, hard x-ray pulses from a synchrotron, the temporal evolution (or ``movies'') of material phenomena (structural changes, inelastic deformation, chemical changes) can be observed in single event, dynamic compression experiments. An overview of the DCS capabilities, operational guidelines, and representative results will be presented. [Preview Abstract] |
Thursday, July 13, 2017 10:00AM - 10:15AM |
S3.00003: Time-resolved Small Angle X-ray Scattering During the Formation of Detonation Nano-Carbon Condensates Michael Bagge-Hansen, Josh Hammons, Mike Nielsen, Lisa Lauderbach, Ralph Hodgin, Sorin Bastea, Tony van Buuren, Phil Pagoria, Chadd May, Brian Jensen, Rick Gustavsen, Erik Watkins, Millie Firestone, Dana Dattelbaum, Larry Fried, Matt Cowan, Trevor Willey Carbon nanomaterials are spontaneously generated under high pressure and temperature conditions present during the detonation of many high explosive (HE) materials. Thermochemical modeling suggests that the phase, size, and morphology of carbon condensates are strongly dependent on the type of HE used and associated evolution of temperature and pressure during the very early stages of detonation. Experimental validation of carbon condensation under these extreme conditions has been technically challenging. Here, we present synchrotron-based, time-resolved small-angle x-ray scattering (TR-SAXS) measurements collected during HE detonations, acquired from discrete sub-100 ps x-ray pulses, every 153.4 ns. We select from various HE materials and geometries to explore a range of achievable pressures and temperatures that span detonation conditions and, correspondingly, generate an array of nano-carbon products, including nano-diamonds and nano-onions. The TR-SAXS patterns evolve rapidly over the first few hundred nanoseconds. Comparing the results with modeling offers significant progress towards a general carbon equation of state. Prepared by LLNL under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, July 13, 2017 10:15AM - 10:30AM |
S3.00004: Evolution of nanocarbon structure in shock-induced chemical reactions Rachel C. Huber, Erik B. Watkins, Arianna E. Gleason, Dana M. Dattelbaum, David W. Podlesak, Richard L. Gustavsen, Richard L. Sandberg, Cynthia A. Bolme, Millicent A. Firestone, Bryan S. Ringstrand, Eric Galtier, Hae Ja Lee Carbon chemistry in the pressure ($P)$ and temperature ($T)$ regimes induced by shock compression includes phase transformation, nucleation and growth and, depending on the thermodynamic conditions, a variety of carbon allotropes and morphologies may form and evolve. Time resolved x-ray scattering experiments on the Matter in Extreme Conditions (MEC) beamline at the Linac Coherent Light Source (LCLS) were used to probe the structure of shock compressed carbon in real time. Shocks were delivered to carbon samples using 20 J laser pulses with 10-20 ns duration and 50 fs x-ray pulses were timed to interrogate the material response relative to shock arrival. A diagnostic suite including Velocity Interferometer System for Any Reflector (VISAR) to measure the $P$ of the shock state and simultaneous x-ray diffraction (XRD) and small angle x-ray scattering (SAXS) to obtain structural information bridging from atomistic to meso length scales was employed. Carbon formation was investigated over a range of $P$ conditions (10-120 GPa) in highly oriented pyrolytic graphite (HOPG) and amorphous carbon samples. Phase transformations to hexagonal and cubic diamond as a function of $P$ and starting material and enhancement of atomistic ordering in shocked amorphous carbon were observed. LA-UR-17-21340 [Preview Abstract] |
Thursday, July 13, 2017 10:30AM - 10:45AM |
S3.00005: Time-Resolved Full-Field X-ray Scatter Imaging of Small-Scale High Explosive Detonations Joshua Hammons, Michael Bagge-Hansen, Michael Nielsen, Lisa Lauderbach, Ralph Hodgin, Nicholas Sinclair, William Shaw, Tony Van Buuren, Larry Fried, Matt Cowan, Trevor Willey Radiographic imaging using a series of singles pulses from synchrotron storage rings or x-ray free-electron lasers gives new insight into dynamic phenomena. One limitation of these sources is that the native and natural beam size at most end-station hutches is, at best, of mm-scale dimensions. Here, we describe a method for collecting full-field, radiographic images of cm-scale phenomena using focused pink-beam and scattering the x-rays, effectively creating point-source images. Although currently photon starved and highly dependent on parameters chosen (such as source-to-object and source-to-detector distances, scattering material, etc.) we are continuously improving the technique. At the Dynamic Compression Sector at the Advanced Photon Source, we use this capability to image detonation phenomena, particularly direct imaging of detonator performance, imaging initiation and run-up to detonation, imaging differences in ideal vs. non-ideal explosives, and have a goal to determining density during detonation at 10's of microns in resolution. In this presentation, we summarize our progress developing and using this technique. [Preview Abstract] |
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