A5068164833- Energetic Materials and Combustion
- High-pressure geophysics and materials
- High-Velocity Impact and Material Behavior
- Laser-Plasma Interactions and Diagnostics
- Advanced X-ray Imaging Techniques
- Metal and Thin Film Mechanics
- Nuclear Physics and Applications
- Crystallography and molecular interactions
- Boron and Carbon Nanomaterials Research
- Ion-surface interactions and analysis
- Combustion and Detonation Processes
- Diamond and Carbon-based Materials Research
- Thermal and Kinetic Analysis
- Integrated Circuits and Semiconductor Failure Analysis
- Chemical Thermodynamics and Molecular Structure
- Force Microscopy Techniques and Applications
- Gas Dynamics and Kinetic Theory
- Electromagnetic Launch and Propulsion Technology
- Nonlinear Optical Materials Research
- Nuclear reactor physics and engineering
- Particle Accelerators and Free-Electron Lasers
- Crystallography and Radiation Phenomena
- High voltage insulation and dielectric phenomena
- Laser-Matter Interactions and Applications
- X-ray Spectroscopy and Fluorescence Analysis
Los Alamos National Laboratory
2015-2024
Eureka Scientific
2020
Los Alamos National Security (United States)
2017
SLAC National Accelerator Laboratory
2016
National Security Technologies (United States)
2013
Argonne National Laboratory
2012-2013
Washington State University
2007-2009
Carnegie Mellon University
2007
The highly transient nature of shock loading and pronounced microstructure effects on dynamic materials response call for in situ, temporally spatially resolved, x-ray-based diagnostics. Third-generation synchrotron x-ray sources are advantageous phase contrast imaging (PCI) diffraction under loading, due to their high photon fluxes, coherency, pulse repetition rates. feasibility bulk-scale gas gun experiments with PCI measurements was investigated at the beamline 32ID-B Advanced Photon...
Investigation of deformation beginning with elasticity and continuing through the elastic–plastic transition to incipient cracking has been conducted for (210), (021) (001) oriented single crystals explosive cyclotrimethylene trinitramine, commonly known as "RDX". Nanoindentation was performed a conical tip over range loads. The resulting load–depth data exhibited distinct, reproducible, orientation-dependent load excursions demonstrating transitions. Indent impressions were imaged by atomic...
The propagation of shock waves normal to (111) in the energetic molecular crystal cyclotrimethylene trinitramine (RDX) has been studied using large-scale dynamics simulations. Partial dislocation loops with Burgers vector 0.16[010] are nucleated homogeneously on (001) at Rankine–Hugoniot pressures greater than 1.3 GPa. Calculations [010] cross-section generalized stacking fault energy surface as a function applied pressure along [001] reveals that enclosed by partial is rendered metastable...
Plate impact experiments were performed on oriented single crystals of the energetic material cyclotrimethylene trinitramine (RDX). The to determine anisotropic dynamic yield point for RDX crystal, as well provide data continuum modeling efforts. Impact was (111), (210), and (100) planes access 3, 2, 0 slip systems, respectively. Velocity history profiles measured using Doppler interferometry. Impacts (210) plane resulted in nominally conventional results, with distinct elastic plastic...
Understanding the dynamic response of materials at extreme conditions requires diagnostics that can provide real-time, in situ, spatially resolved measurements on nanosecond timescale. The development methods such as phase contrast imaging (PCI) typically used synchrotron sources offer unique opportunities to examine material response. In this work, we report ultrafast, high-resolution, PCI shock compressed with 3 μm spatial resolution using a single 60 ps X-ray bunch. These results firmly...
Abstract Crystalline molecular explosives are key components of engineered explosive formulations. In precision applications a high degree consistency and predictability is desired under range conditions to variety stimuli. Prediction behaviors from mechanical response failure detonation initiation performance the material linked accurate knowledge structure first stage deformation: elasticity. The elastic pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX),...
Inertial confinement fusion (ICF) holds increasing promise as a potential source of abundant, clean energy, but has been impeded by defects such micro-voids in the ablator layer fuel capsules. It is critical to understand how these interact with laser-driven shock waves that compress pellet. At Matter Extreme Conditions (MEC) instrument at Linac Coherent Light Source (LCLS), we utilized an x-ray pulse train ns separation, microscope, and ultrafast imaging (UXI) detector image wave...
We recently proposed that the change observed in elastic-plastic response of (111)-oriented cyclotrimethylene trinitramine (RDX) crystals under shock compression is caused by an anomalous hardening mediated homogeneous nucleation partial dislocation loops with Burgers vector 0.16[010] on (001) {Cawkwell et al., [J. Appl. Phys. 107, 063512 (2010)]}. The orientation dependencies (001)[010] slip system suggested (021)-oriented RDX should also display hardening. Molecular dynamics simulations...
Examining the evolution of material properties at extreme conditions advances our understanding numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved response nanosecond time resolution. In this work, we examined jet formation a Richtmyer-Meshkov instability cerium...
In recent years, neutron radiography and tomography have been applied at different beam lines Los Alamos Neutron Science Center (LANSCE), covering a very wide energy range. The field of energy-resolved imaging with epi-thermal neutrons, utilizing absorption resonances for contrast as well quantitative density measurements, was pioneered the Target 1 (Lujan center), Flight Path 5 line continues to be refined. Applications include: metallic ceramic nuclear fuels, fission gas fossils studies...
A continuum model for the high-rate, thermo-mechanical deformation of single-crystal cyclotrimethylene trinitramine (RDX) is developed. The includes effects anisotropy, large deformations, nonlinear thermo-elasticity, phase transformations, and plastic slip. multiplicative decomposition gradient used. volumetric elastic component accounted through a free-energy based equation state low- (α) high-pressure (γ) polymorphs RDX. Crystal plasticity addressed using phenomenological thermal...
Iron is a key constituent of planets and an important technological material. Here, we combine in situ ultrafast x-ray diffraction with laser-induced shock compression experiments on Fe up to 187(10) GPa 4070(285) K at 10^{8} s^{-1} strain rate study the plasticity hexagonal-close-packed (hcp)-Fe under extreme loading states. {101[over ¯]2} deformation twinning controls polycrystalline microstructures occurs within 1 ns, highlighting fundamental role hcp polycrystals high rates. The measured...
The impact system for ultrafast synchrotron experiments, or IMPULSE, is a 12.6-mm bore light-gas gun (<1 km/s projectile velocity) designed specifically performing dynamic compression experiments using the advanced imaging and X-ray diffraction methods available at sources. system, capable of reaching velocities up to 1 km/s, was be portable quick insertion/removal in experimental hutch Sector 32 ID-B Advanced Photon Source (Argonne, IL) while allowing target chamber rotate sample alignment...
Equations of state for the α and γ polymorphs energetic molecular crystal cyclotrimethylene trinitramine (RDX) have been developed from their Helmholtz free energies. The ion motion contribution to energy is represented by Debye models with density-dependent temperatures that are parameterized vibrational densities states computed dispersion-corrected density functional theory. By separating into low frequency modes mainly lattice phonon character high intramolecular we were able...
The ability to examine the dynamic response of materials at extreme conditions requires diagnostics that can provide real-time, in situ, spatially resolved measurements appropriate length scale. Recent advances synchrotron sources and coupled loading platforms are transforming compression field allow for such investigations. In current work, recent experimental efforts on IMPULSE (IMPact System ULtrafast Synchrotron Experiments) capability Advanced Photon Source (Argonne, IL) will be...
Crack initiation and propagation is a common concern for molecular composites such as plastic bonded explosives (PBXs) pharmaceutical tablets. Under compressive stresses, cracks form at contacts between crystals propagate along crystal-binder interfaces, causing composite failure. To investigate this process, interfaces have been characterised their mechanical properties tested. Here, samples were created with representative of those in PBXs surface energy measurements neutron reflectometry...
The mechanical and chemical response of energetic materials is controlled by a convolution deformation mechanisms that span length scales evolve during impact. Traditional methods use continuum measurements to infer the microstructural whereas advances in synchrotron capabilities diagnostics are providing new, unique opportunities interrogate real time situ. Experiments have been performed on new gas-gun system (IMPact for Ultrafast Synchrotron Experiments) using single X-ray bunch phase...
The elastic tensor of 1,3,5-trinitroperhydro-1,3,5-triazine (also known as RDX, hexogen, and cyclotrimethylene trinitramine) was determined using Brillouin spectroscopy as-grown single crystals. This study addresses inconsistencies in the literature between measurements made GHz frequency range various techniques kHz-MHz range. These results are consistent with previous also velocity at 15 picosecond acoustic interferometry. disagreement previously published spectroscopy, there differences...
Abstract The dependence of the components elastic stiffness tensors (or constants) organic explosives PETN, RDX, CL‐20, DAAF, FOX‐7, and HMX on hydrostatic pressure up to 10 GPa have been computed using dispersion‐corrected density functional theory. We report evolution lattice parameters non‐zero stiffnesses for tetragonal, orthorhombic, monoclinic crystal symmetries. Linear quadratic dependencies volumetric compression are tabulated use in single plasticity models.
Abstract The onset of plastic deformation was investigated using nanoindentation in single crystals the explosive cyclotrimethylene trinitramine (RDX). Cleavage and habit planes were tested revealing a range yielding behaviors. Smooth unprocessed exhibited distinct yield points near theoretical shear strength; produced by cleavage yielded at lower applied stresses. Cumulative probability distributions maximum stresses used to illustrate representative behavior for samples prepared different...