Correlation Between Hot Spots and 3-D Defect Structure in Single and Polycrystalline High-Explosive Materials NLV-035-16, Year 3 of 3
Explore the source record for details and available documents.
36 MATERIALS SCIENCE↗
Engineering topics
Fussell, Zachary
Publications and source records attributed to Fussell, Zachary.
Shock Recovery of High-Pressure Bismuth-II
Between 0 and 10 GPa, there are nine different bismuth phases. Thermodynamically speaking, none of these phases are accessible at ambient conditions, and this inability to recover them has been confirmed over a number of experiments. Here, an impedance mismatched shockwave experiment provides a stepwise pressure release path; leading to the first recovery of high-pressure bismuth-II to ambient conditions, identified by synchrotron X-ray micro-diffraction. Our work shows shock-compression provides a means of recovering high-pressure phases that otherwise elude decompression.
36 MATERIALS SCIENCE↗
Nevada National Security Site Site-Directed Research and Development Report (FY 2018 Annual Report)
This report compiles multiple articles describing activities developed and performed under the Site-Directed Research and Development Program for the benefit the Nation during Fiscal Year 2018. Sustained investment and ongoing core innovation are the keys to successful research and development programs. These elements drive the Site-Directed Research and Development (SDRD) Program and provide solutions to some of the most challenging problems our nation and our allies face. Our Nevada enterprise, consisting of both our management and operating entity and our NNSA field office, is aggressively investing in SDRD and injecting innovation through strategic partnerships. Our partnerships with universities, industry, and our sister institutions within the National Nuclear Security Administration (NNSA) build upon our core capabilities and allow us to create innovative solutions to support our mission requirements. In 2018, we raised the investment level of SDRD for only the second time in the history of the program. Nearly at our congressionally authorized limit, SDRD has substantial resources to successfully address numerous issues. Investment is only one part of the equation; innovation is generated through collaborations that bring discovery and provide the “technical differentiation” and the return on investment we seek. This report demonstrates an enduring theme of how partnerships help us drive the best outcomes and provide the maximum impact possible, while using our resources efficiently.
36 MATERIALS SCIENCE↗
Postaragonite phases of CaCO 3 at lower mantle pressures
The stability, structure, and properties of carbonate minerals at lower mantle conditions have significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon hybridization, which has relevance for the storage of carbon within the deep mantle. Using high-pressure synchrotron x-ray diffraction in a diamond anvil cell coupled with direct laser heating of CaCO 3 using a CO 2 laser, we identify a crystalline phase of the material above 40 GPa—corresponding to a lower mantle depth of around 1000 km—which has first been predicted by ab initio structure predictions. Here, the observed sp 2 carbon hybridized species at 40 GPa is monoclinic with P2 1 /c symmetry and is stable up to 50 GPa, above which it transforms into a structure which cannot be indexed by existing known phases. A combination of ab initio random structure search (AIRSS) and quasiharmonic approximation (QHA) calculations are used to re-explore the relative phase stabilities of the rich phase diagram of CaCO 3 . Nudged elastic band (NEB) calculations are used to investigate the reaction mechanisms between relevant crystal phases of CaCO 3 and we postulate that the mineral is capable of undergoing sp 2 – sp 3 hybridization change purely in the P2 1 /c structure—forgoing the accepted postaragonite Pmmn structure.
36 MATERIALS SCIENCE↗
Correlation between hot spots and 3-D defect structure in single and polycrystalline high-explosive materials
This article presents a novel approach that spatially identifies inhomogeneities from microscale (defects, con-formational disorder) to mesoscale (voids, inclusions) using synchrotron x-ray methods: tomography, Lang topography, and micro-diffraction mapping. These techniques provide a non-destructive method for characterization of mm-sized samples prior to shock experiments. These characterization maps can be used to correlate continuum level measurements in shock compression experiments to the mesoscale and microscale structure.
36 MATERIALS SCIENCE↗
Correlation Between Hot Spots and 3-D Defect Structure in Single and Polycrystalline High-Explosive Materials, NLV-035-16, Year 2 of 3
Presentation describes new approach to determine and map defects present in common HE materials to later correlate to hot spots seen during shock using X-ray tomography for meso-scale defects, Lang topography for fully 3-D quantitative assessment, and pre-shock diagnostic tool for pre-shock.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Material Studies using and developing X-ray based diagnostics
Presentation address the question of the role played by defects in hot spot formation during initial stages of detonation.
36 MATERIALS SCIENCE↗