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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Study of Electric Explosion of Flat Micron-Thick Foils at Current Densities of (5–50)×10 8 A/cm 2

Electric explosions of flat Al, Тi, Ni, Cu, and Та foils with thicknesses of 1–16 μm, widths of 1–8 mm, and lengths of 5–11 mm were studied experimentally on the BIN, XP, and COBRA high-current generators at currents of 40–1000 kA and current densities of (5–50) × 10 8 A/cm 2 . The images of the exploded foils were taken at different angles to the foil surface by using point projection radiography with an X-pinch hot spot as the radiation source, the spatial resolution and exposure time being 3 μm and 50 ps, respectively, as well by the laser probing method with a spatial resolution of 20 μm and an exposure time of 180 ps. In the course of foil explosion, rapidly expanding objects resembling the core and corona of an exploded wire were observed. To this end, it is shown that the core of the exploded foil has a complicated time-varying structure.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Codes for "Shallow Soil Response to a Buried Chemical Explosion with Geophones and Distributed Acoustic Sensing" DAG - 01101646

The codes reproduce the figures of the manuscript entitled "Shallow Soil Response to a Buried Chemical Explosion with Geophones and Distributed Acoustic Sensing" submitted to Journal of Geophysical Research - Solid Earth. Geophone data and Distributed acoustic sensing (DAS) data recorded during the Phase II of the The Source Physics Experiment (SPE) along a fiber-optic cable offshore were processed to understand the response of the shallow subsurface to an explosion. This Ground-based Nuclear Detonation Detection (GNDD), Low Yield Nuclear Monitoring (LYNM), and Source Physics Experiment (SPE) research was funded by the National Nuclear Security Administration, Defense Nuclear Nonproliferation Research and Development (NNSA DNN R&D).

Viens, Loic↗
DOE OSTI2024

Subsurface Spectroscopy of Thermal Degradation Inside an Inert Plastic Bonded Explosive (PBX) Simulant Using Feedback-Assisted Wavefront Shaping

We characterize the subsurface thermal degradation of an inert analog of high-explosive molecular crystals (Eu:Y(acac) 3 (DPEPO)) (EYAD) embedded inside of a plastic bonded explosive simulant using feedback-assisted wavefront shaping-based fluorescence and Raman spectroscopies. This technique utilizes wavefront shaping to focus pump light inside a heterogeneous material onto a target particle, which significantly improves its spectroscopic signature. We find that embedding the EYAD crystals in the heterogeneous polymer results in improved thermal stability, relative to bare crystal measurements, with the crystal remaining fluorescent to >612 K inside of the heterogeneous material, while the bare crystal’s fluorescence is fully quenched by 500 K. We hypothesize that this improvement is due to the polymer restricting the effects of EYAD melting, which occurs at 400 K and is the primary mechanism for spectroscopic changes in the temperature range explored.

Anderson, Benjamin R.↗
DOE OSTI2022

Raman Spectroscopy Characterization of Nuclear Materials and Soot from High Explosives

Vibrational and luminescence spectroscopy were used in the investigation of U and Pu-bearing compounds and soot from high explosives testing. Key spectroscopic signatures of UF4 and its hydrates, PuO 2 , and soot from different explosives will be presented. The United States Government retains and the publisher, by accepting this article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes.

Villa-Aleman, Eliel↗
DOE OSTI2016

Source spectra of the first four Source Physics Experiments (SPE) explosions from the frequency-domain moment-tensor inversion

In this study, I used seismic waveforms recorded within 2 km from the epicenter of the first four Source Physics Experiments (SPE) explosions to invert for the moment-tensor spectra of these explosions. I employed a one-dimensional (1D) Earth model for Green's function calculations. The model was developed from P- and R g -wave travel times and amplitudes. I selected data for the inversion based on the criterion that they had consistent travel times and amplitude behavior as those predicted by the 1D model. Due to limited azimuthal coverage of the sources and the mostly vertical-component-only nature of the dataset, only long-period, volumetric components of the moment-tensor spectra were well constrained.

58 GEOSCIENCES↗
DOE OSTI2018

Seismic Models for Near-Surface Explosion Yield Estimation in Alluvium and Sedimentary Rock

Seismic ground-motion data provide valuable constraints on explosion characteristics, such as yield and height-of-burst/depth-of-burial (HOB/DOB). In this study, we investigate a range of seismic amplitude features and their efficacy in minimizing errors associated with yield estimation. Using a set of explosion recordings from experiments conducted in alluvium and sedimentary rock geologies, we investigated the effectiveness of three different seismic feature types over a range of different frequencies. Using both velocity and displacement data, we investigated the zero-to-peak (ZTP) amplitude of the first arriving P wave, the peak-to-peak (PTP) amplitude of the first arriving P wave, and the P rms amplitude over various time windows starting with the P wave. These three basic features were measured on both vertical component only data and the vertical–radial vector sum. In total, there were 56 different combinations investigated. Our seismic models combine the effects of scaled range and scaled HOB/DOB on the observed seismic features. The results show that the vertical–radial vector sum of the ZTP amplitudes measured on displacement seismograms most consistently produce models with the smallest difference between predicted amplitude values and observed amplitude values when accounting for both alluvium and sedimentary rock lithology. The improvement in fit to the data when incorporating the difference in source lithology is significant. Lastly, if an alluvium lithology is assumed for a sedimentary rock lithology, the difference in yield could be up to ~3.0 times the appropriate yield in the far field.

58 GEOSCIENCES↗
DOE OSTI2022

Multi-Event Explosive Seismic Source for the 2022 M w 6.3 Hunga Tonga Submarine Volcanic Eruption

The eruption of the Hunga Tonga–Hunga Ha’apai submarine volcano on 15 January 2022 produced a variety of geophysical responses, including a significant seismic signal. We study the seismic source process of this event by inverting for moment tensors (MTs) using regional surface waves (Rayleigh, Love). By comparing inversion results for the eruption with eight nearby earthquakes, we show that it is possible to discriminate MT source types. Our inversion yields a shallow explosive source for the eruption and reveals the importance of trade-offs among depth, magnitude, and source type. We illustrate these trade-offs by representing the misfit variations over the eigenvalue lune. Finally, we invert for the source-time function of the sequence of explosions that occurred in the first minutes of the eruption. The multi-event source-time function comprises four subevents spanning ~270 s, with a total magnitude estimate of M w 6.34 ± 0.10.

58 GEOSCIENCES↗
DOE OSTI2013

Ten Trials at Lower Slobbovia: Searching for Repetitive Electromagnetic and Seismoacoustic Signatures in Explosions

We performed a series of ten explosion tests, each test being a single 10-kg cylinder of Comp-B with a PBXN-9 booster. Eight of the tests were placed 2 m above ground level, one was at ground level, and one was 1 m below ground in a backfilled hole. The explosions were monitored by radio antennas to detect electromagnetic emissions and seismo-acoustic instrumentation. We found that certain aspects of the radiofrequency emission regimes repeated from test to test. Some features showed a systematic variation across tests, which we interpret as the effect of each detonation on the nearby ground. The radio emissions were probably from the high-temperature detonation shock, follow-on combustion, and frictional charging of dirt entrained by the blast. The below-ground test in particular generated an anomalously-high level of RF at both low and high frequencies, presumably due to the large amount of dirt and rock involved. The seismoacoustic observations clearly discriminate the buried shot from the table and surface shots, which appear as a single population. Seismoacoustic waveforms from repeating tests at local distances have highly self-similar waveforms but amplitudes are strongly dependent on atmospheric conditions. We show that we can correct for meteorological effects on amplitude for upward-refracting atmospheres, but that correction for downward-refracting atmospheric profiles requires a coupled correction for topography.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

The Biggest Explosions in the Universe [Poster]

While most supermassive stars formed in the early universe are expected to have collapsed to black holes, those with masses of ~50,000 solar masses are predicted to have exploded as extremely energetic supernovae. These explosions would have been ~10,000 times more energetic than most supernovae today, making them the largest explosions in the history of the universe. In addition to releasing enormous amounts of mechanical and thermal energy into their surroundings, they also enrich the primordial gas with the first heavy elements.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Understanding Debris-Background Ion Interactions in High Altitude Nuclear Explosions

The Starfish Prime event produced many interesting nuclear, electromagnetic, atomic and plasma effects, which have led over the past 50 years to much research in understanding the overall phenomenology of high altitude nuclear explosions (HANE). At altitudes lower than Starfish, where collisional processes come into play, the physics of a nuclear fireball in the atmosphere is well understood. But at high altitudes, where collisions are much weaker, the fundamental issue how the ionized weapon debris is stopped in the ionosphere in order to produce a relatively localized debris cloud remains unresolved. In the last 30 years this issue has been investigated in the laboratory using high-power lasers to simulation the explosion and subsequent expansion of the debris plasma. While experiments that were carried out on the Helios laser at Los Alamos and then later on the Pharos laser at NRL were able to produce some plasma conditions representative of the HANE environment and obtained interesting results, they were not very successful in addressing the basic debris-air coupling problem in the collisionless regime. This problem is being revisited in a new DTRA-funded experimental program with the 500 J Raptor glass laser on the Large Plasma Device (LAPD) at UCLA.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Probability Calculation of Grit-Grit Interaction on a Plastic Bonded Explosive During Glancing Impacts

Recent experiments indicate that frictionally heated grit can act as effective hot spots for the ignition of PBX 9501 (Parker et al. (2013)). The most common mode for hot spot formation is when a piece of grit is dragged by the explosive across a high melting point surface, such as steel. This leads to a hot spot with a temperature of the melting point of the surface. For high melting point surfaces this can be hot enough to lead to ignition. It is believed that an easy way to mitigate this is to use surfaces with low melting points, which means the hot spots formed cannot become hot enough to ignite the explosive during the duration of the impact (Bowden and Gurton (1948)). However, when surfaces have a similar hardness to the PBX (such as many plastics), hot spots of sufficient temperature for ignition can still be formed by the collision of two grit particles, one being dragged by the PBX with the other being stationary on the surface. In order to mitigate the probability of ignition it is desirable to know how clean the work surfaces need to be in order to minimize the acceptable risk of an event. Two cases need to be considered: first, what is probability that a dropped piece of PBX will contact one or more grit particles? This will lead to an estimate of how ”clean” a surface needs to be when working with unmitigated, high-melting point surfaces. Second, what is the probability that a dropped piece of PBX will lead to a collision between two or more grit particles? This will give an estimate how clean a surface needs to be when working with low melting point surfaces.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Development of ab initio techniques critical for future science-based explosives R&D

Density Functional Theory (DFT) has emerged as an indispensable tool in materials research, since it can accurately predict properties of a wide variety of materials at both equilibrium and extreme conditions. However, for organic molecular crystal explosives, successful application of DFT has largely failed due to the inability of current exchange-correlation functionals to correctly describe intermolecular van der Waals (vdWs) forces. Despite this, we have discovered that even with no treatment of vdWs bonding, the AM05 functional and DFT based molecular dynamics (MD) could be used to study the properties of molecular crystals under compression. We have used DFT-MD to predict the unreacted Hugoniots for PETN and HNS and validated the results by comparison with crystalline and porous experimental data. Since we are also interested in applying DFT methods to study the equilibrium volume properties of explosives, we studied the nature of the vdWs bonding in pursuit of creating a new DFT functional capable of accurately describing equilibrium bonding of molecular crystals. In this report we discuss our results for computing shock Hugoniots of molecular crystals and also what was learned about the nature of bonding in these materials.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Ranchero Armature Test LA-19.4-CT-3: PBX-9501 Explosive with no smoothing layer. Firing point 88, 9/16/13

LA-19.4-CT-3 (CT-3) was the third camera test in a series beginning in 1/11, which diagnose the performance of 6 mm thick, 6061 T-0 Al Ranchero armatures. [The test LA-43-CT-2 (CT-2) is described in LA-UR-14-21983.] The goal of CT-3 was to verify that PBX-9501, with 18 mm point spacing and no smoothing layer, could be used for Ranchero generator armatures in place of PBXN-110, which had been used in all previous Ranchero applications. CT-1 and CT-2 both had 43 cm long slapper detonator systems imbedded in the cast PBXN-110 explosive, but manufacturing a charge for a similar 9501 test was not cost effective. Instead, a single cylinder of 9501, 19.368 cm long and 15.494 cm (6.100”)in diameter, had a groove machined to accommodate a row of 11 SE-1 detonators with 18 mm point spacing along the mid-plane of the cylinder. The expansion of the armature looks like a slapper assembly along almost ½ of the circumference, and provides adequate proof of concept. Removing the smoother from PBXN-110-driven armatures increased the armature velocity from 3.1 mm/μs to 3.3 mm/μs, as seen in CT-2, and the velocity measured on CT-3 increased to 3.8 mm/μs. In addition, the camera records show that the surface of the armature is smooth enough, and free from ruptures for an expansion of greater that 2X. The advantage of using 9501 is that it precludes concerns about blow-outs seen when bubbles are left in the cast material, and gives extra velocity. The disadvantage is that the machined explosives are more expensive.

42 ENGINEERING↗
DOE OSTI2015

Historical Survey: German Research on Hydrogen Peroxide/Alcohol Explosives

Discussion of HP/fuel explosives in the scientific literature dates back to at least 1927. A paper was published that year in a German journal entitled On Hydrogen Peroxide Explosives [Bamberger and Nussbaum 1927]. The paper dealt with HP/cotton/Vaseline formulations, specifically HP89/cotton/Vaseline (76/15/9) and (70/8.5/12.5). The authors performed experiments with charge masses of 250-750 g and charge diameters of 35-45 mm. This short paper provides brief discussion on the observed qualitative effects of detonations but does not report detonation velocities.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2016

Air Blasts from Cased and Uncased Explosives

The problem of a spherical blast in air is solved using the STUN code. For bare charges, the calculations are shown to be in excellent agreement with previous published results. It is demonstrated that, for an unconfined (uncased) chemical explosive, both range and time to effect scale inversely as the cube root of the yield and directly as the cube root of the ambient air density. It is shown that the peak overpressure decays to roughly 1/10 of ambient pressure in a scaled range of roughly 10 m/kg 1/3 at sea level. At a height of 30 km, where the ambient density is a factor of 64 less, the range to the same decay increases to 40 m/kg 1/3 . As a direct result of the scaling a single calculation suffices for all charge sizes and altitudes. Although the close-in results are sensitive to the nature of the explosive source and the equation of state of the air, this sensitivity is shown to virtually disappear at scaled ranges > 0.5 m/kg 1/3 .

42 ENGINEERING↗
DOE OSTI2016

Analysis of MINIE2013 Explosion Air-Blast Data

We report analysis of air-blast overpressure measurements from the MINIE2013 explosive experiments. The MINIE2013 experiment involved a series of nearly 70 near-surface (height-ofburst, HOB, ranging from -1 to +4 m) low-yield (W=2-20 kg TNT equivalent) chemical highexplosives tests that were recorded at local distances (230 m – 28.5 km). Many of the W and HOB combinations were repeated, allowing for quantification of the variability in air-blast features and corresponding yield estimates. We measured canonical signal features (peak overpressure, impulse per unit area, and positive pulse duration) from the air-blast data and compared these to existing air-blast models. Peak overpressure measurements showed good agreement with the models at close ranges but tended to attenuate more rapidly at longer range (~ 1 km), which is likely caused by upward refraction of acoustic waves due to a negative vertical gradient of sound speed. We estimated yields of the MINIE2013 explosions using the Integrated Yield Determination Tool (IYDT). Errors of the estimated yields were on average within 30% of the reported yields, and there were no significant differences in the accuracy of the IYDT predictions grouped by yield. IYDT estimates tend to be lower than ground truth yields, possibly because of reduced overpressure amplitudes by upward refraction. Finally, we report preliminary results on a development of a new parameterized air-blast waveform.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2017

Notes on the ExactPack Implementation of the DSD Explosive Arc Solver

It has been shown above that the discretization scheme implemented in the ExactPack solver for the DSD Explosive Arc equation is consistent with the Explosive Arc PDE. In addition, a stability analysis has provided a CFL condition for a stable time step. Together, consistency and stability imply convergence of the scheme, which is expected to be close to first-order in time and second-order in space. It is understood that the nonlinearity of the underlying PDE will affect this rate somewhat.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

New Source Model for Chemical Explosions

With sophisticated inversion scheme, we recover characteristics of SPE explosions such as corner frequency f c and moment M 0 , which are used to develop a new source model for chemical explosions.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗