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Results for “HIGH EXPLOSIVES”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Three Decades of Explosive High Energy Transients

Gamma-Ray Bursts are the most brilliant explosions in space. The first GRB was discovered on 1967, just 40 years ago. It took several years and multiple generations of space and ground instruments to unravel some of the mysteries of this phenomenon. However, many questions remain open today. I will discuss the history, evolution and current status of the GRB field and its contributions in our understanding of the transient high energy sky. Finally, I will describe how GRBs can be utilized in future missions as tools, to probe the cosmic chemical evolution of the Universe and the star formation rates.

Kouveliotou, Chryssa↗
DOE OSTI2020

Numerical Considerations in the Modeling of a High Explosive Cylinder Experiment Using an ALE Continuum Mechanics Code

A series of experiments involving the detonation of PBX 9501 encased in a copper cylinder are modeled with the objective of evaluating a proposed set of phenomenological parameters for the Wescott–Stewart–Davis reactive burn model. The numerical analysis is conducted using the Los Alamos continuum mechanics code FLAG. Numerical considerations pertaining to various aspects of modeling the experiments using FLAG are discussed. It is shown that use of the proposed set of phenomenological parameters results in predictions of free-surface velocity that match empirically measured velocities reasonably well.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Tetrazolyl Triazolotriazine: A New Insensitive High Explosive

A triazolotriazine carbonitrile ( 1 ) was formed by diazotization of 3–amino–5–cyano–1,2,4–triazole followed by treatment with nitroacetonitrile. Cyclization of the C≡N bond with sodium azide results in a tetrazolyl triazolotriazine ( 2 ). Formation of the sodium salt of 2 , followed by metathesis with [PPN][Cl] resulted in the organic salt 3 . Compounds 1 , 2 , and 3 were characterized by elemental analysis and infrared, 1 H, and 13 C{ 1 H} NMR spectroscopy and 1 and 3 were characterized by single–crystal X–ray diffraction. Compound 2 has a density of 1.819 g cm –1 , is thermally stable up to 305 °C, and is insensitive to impact, friction, and electrical discharge. The detonation pressure and velocity of 2 are calculated to be 27.04 GPa and 8.312 km s –1 , respectively, making this a 1,3,5–triamino–2,4,6–trinitrobenzene (TATB) replacement candidate.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2026

Direct observation of diamond formation in a shock-compressed high explosive

Understanding the formation timescale and structure of carbonaceous reaction products is critical for modeling the high-pressure equation-of-state of organic materials. We use the National Ignition Facility to shock-compress polycrystalline TATB (C 6 H 6 N 6 O 6 ) samples to ~70–130 GPa and ~4000–5500 K, employing in situ nanosecond X-ray diffraction to probe reaction products and velocimetry to measure transmitted compression wave profiles. Our diffraction data is consistent with the formation of diamond over timescales less than ~60 ns. This represents carbon condensation from a molecular explosive on timescales three times faster than previously reported and the earliest observation of diamond produced from reacting TATB. Reactive flow simulations with explicit chemistry reproduce the observed temporal structure within wave profiles to inform the distribution of P-T states. These findings provide direct evidence of ultrafast diamond formation in a reactive system at extreme conditions and provide new constraints for models of shock and detonation chemistry.

Clarke, Samantha M. [Lawrence Livermore National L↗
DOE OSTI2019

Nonlinear Resonant Ultrasound Spectroscopy for Predicting Sensitivity to Initiation in Granular High Explosives

Abstract Nonlinear Resonant Ultrasound Spectroscopy (NRUS) is a technique that can measure bulk nonlinear coefficients of the nonlinear elastic modulus for a material. NRUS has been used to identify damage in a variety of granular materials including rocks and concrete. Some energetic materials, such as Pentaerythritol Tetranitrate (PETN), are commonly fielded as pressed granular compacts. It is well known that the sensitivity to initiation of these materials is heavily dependent on their microstructure, and that microstructure changes naturally (becomes damaged) over time. In this study, we examine the use of NRUS to identify changes in microstructure between pristine and thermally aged PETN pellets. In particular, we examine the relationship between the bulk hysteretic nonlinearity, α , of the pellets and time spent at temperature, powder specific surface area (SSA), and sensitivity to initiation. We find that, in general, α does not increase uniformly for all pellets within a single thermal aging condition. However, when the pellets are test fired to determine sensitivity to initiation, there is a strong correlation between α and firing voltage threshold. NRUS‐measured α has the added benefit that the measurements can be made in situ and on benchtop scales.

Schulze, Peter↗
DOE OSTI2017

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↗
DOE OSTI2015

Ejected particle size measurement using Mie scattering in high explosive driven shockwave experiments

In this paper, we report on the development of a diagnostic to provide constraints on the size of particles ejected from shocked metallic surfaces. The diagnostic is based on measurements of the intensity of laser light transmitted through a cloud of ejected particles as well as the angular distribution of scattered light, and the analysis of the resulting data is done using the Mie solution. Finally, we describe static experiments to test our experimental apparatus and present initial results of dynamic experiments on Sn targets. Improvements for future experiments are briefly discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗