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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Casings for use in a system for fracturing rock within a bore

In disclosed explosive units for use in a wellbore, the casing can include a tubular outer body comprising grooves, pockets, or other variances in thickness that create stress concentrations that promote shear and tensile fragmentation instead of ductile expansion of the casing, which can negatively impact permeability of a wellbore. In other embodiments, the casing can comprise non-ductile and/or reactive material which responds to explosive or high temperature loading by brittle failure, disintegration, melting, burning, and/or chemically reacting with the energetic materials and/or the borehole environment. Such embodiments can enhance the permeability of the wellbore after detonation.

03 NATURAL GAS↗
DOE OSTI2021

Dynamic Particulate Behavior in Turbulent Media

Presentation to be given on WebEx meeting February 16, Works in Progress seminar. There are 4 embedded videos in the presentation (slides 8, 13, and 19). After the 16th, presentation will be uploaded and available on the S&T website, https://insite.nv.doe.gov/Science%26Technology/SitePages/Work%20in%20Progress%20Seminars.aspx

36 MATERIALS SCIENCE↗
DOE OSTI2020

High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 micron diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produces a liquid column that undergoes hydrodynamic breakup into droplets with radii of order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classic Rayleigh-Plateau predictions for instability of viscous fluid column. Above 3.2 eV/atom of deposited energy, wires are seen to abruptly transition to an expanding mixture of micron scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed ‘phase explosion’ in literature. Between these two limits, at 2.5 eV/atom of deposited energy, wire radius is unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Here, thermodynamic calculations are presented that separate cases by temperature obtained during heating: below boiling point, near boiling point, and exceeding boiling point.

42 ENGINEERING↗
DOE OSTI2023

High fidelity ground deposition measurement with robots after explosive radiological dispersion

A team of scientists from the Remote Sensing Laboratory at Joint Base Andrews, Maryland, has assembled a remote-controlled robot to field a few sodium iodide scintillators of different size and shape 18″ above ground for measurement of ground deposition of gamma-emitting particles after an explosion of a radiological dispersal device. This system uses a high-precision differential GPS device with submeter accuracy for radiation mapping. The system is most useful in characterizing large-area contamination and detecting gamma radioactivity in invisible, submicron particulate debris deposited on the ground at surface level or embedded in subsurface up to 3″ deep. The system was assembled as part of a larger effort to integrate advanced radiological detection devices into autonomous or remote-controlled robotic systems to eliminate or minimize the need for emergency responders to enter areas that pose significant health and safety risks to humans following a major radiological incident or accident. Research into autonomous algorithms is required to develop automated robotic systems for radiological survey and characterization activities in highly contaminated areas. The scope of this project also includes developing communications pathways and supporting infrastructure capabilities for different types of robotic technologies. The expected result is an advanced autonomous robotic system with integrated radiation detection electronics that allows emergency response personnel to view data remotely and in real time for radiological emergency response and consequence management purposes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1992

Solar full-disk magnetic field image receiving system and observation software

The paper introduces terminal hardware system of 10 cm high resolution full-disk magnetic field telescope among solar multi-channel telescope produced by Beijing Astronomical Observatory, and its software procedure by using imaging processing as well real time data collecting. These data were processed by Sun Workstation 470/4, including doing some spectrum analysis, the system is unique in the world now. It uses a set of CCD (1320 pixels plus 1035 pixels) of high resolution image explosion, also it has a set of fast and high resolution (1024 pixel plus 1024 pixel) image processor. Moreover, we can obtain higher time and space resolution about solar full-disk magnetic field and velocity field. This will provide excellent means in observation and studies of full-disk solar large-scale magnetic field and velocity field.

Xu, Yan↗
NASA NTRS2019

Late-time observations of the extraordinary Type II supernova iPTF14hls

Aims. We study iPTF14hls, a luminous and extraordinary long-lived Type II supernova, which lately has attracted much attention and disparate interpretation. Methods. We have presented new optical photometry that extends the light curves up to more than three years past discovery. We also obtained optical spectroscopy over this period, and furthermore present additional space-based observations using Swift and HST. Results. After an almost constant luminosity for hundreds of days, the later light curve of iPTF14hls finally fades and then displays a dramatic drop after about 1000 d, but the supernova is still visible at the latest epochs presented. The spectra have finally turned nebular, and our very last optical spectrum likely displays signatures from the deep and dense interior of the explosion. A high-resolution HST image highlights the complex environment of the explosion in this low-luminosity galaxy. Conclusions. We provide a large number of additional late-time observations of iPTF14hls, which are (and will continue to be) used to assess the many different interpretations for this intriguing object. In particular, the very late (+1000 d) steep decline of the optical light curve is difficult to reconcile with the proposed central engine models. The lack of very strong X-ray emission, and the emergence of intermediate-width emission lines including [S II] that we propose originate from dense, processed material in the core of the supernova ejecta, are also key observational tests for both existing and future models.

J. Sollerman↗
DOE OSTI2021

Radiation-Induced Dark Counts for Silicon Single-Photon Detectors in Space

Single-photon detectors operating on satellites for use in a quantum communications network can incur large dark-count-rate increases from the natural radiation environment of space. Displacement damage to the material lattice of a detector from the ionizing radiation can result in a permanent dark-count increase in the detector. In this work, we analyze the radiation-induced dark-count rate of a silicon single-photon avalanche diode onboard a satellite at different orbiting altitudes, as well as, the additional radiation from a nuclear-disturbed environment caused by a high-altitude nuclear explosion. For detectors on low Earth orbit satellites, protons are the biggest source of radiation damage and are best mitigated by choosing an orbit that minimizes exposure when passing through the South Atlantic Anomaly and Polar Cusps. Detectors on medium Earth orbit and geostationary orbit satellites, if shielded by more than 10 mm of aluminum, provide the best platform in terms of the least amount of radiation damage to the detectors. In the event of a high-altitude nuclear explosion, the artificial radiation belts produced by the explosion will cause too much damage to silicon single-photon detectors on low Earth orbit satellites and render them unfit for quantum communications in less than a day. Higher orbit satellites will only suffer minor dark-count-rate increases from the artificial radiation belts.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Shock Initiation Microscopy with High Time and Space Resolution

In this paper, we describe studies of shock initiation and shock-to-detonation transitions in energetic materials using a tabletop shock compression microscope with nanosecond time resolution and micrometer spatial resolution. Planar input shocks with durations of 4–20 ns are produced using 0–4.5 km/s laser-launched flyer plates. Emphasis is on measurements of temperature, velocities, pressure, and microstructure using photon Doppler velocimetry (PDV), optical pyrometry and high-speed videography. Techniques are discussed for fabricating disposable shock target arrays of tiny plastic-bonded explosives (PBX), liquid and powder explosives, and single-crystal explosives for high-throughput studies. Optical temperature measurements of shocked triaminotrinitrobenzene (TATB) are discussed. Since TATB is yellow, we developed methods to correct for the blue absorption to obtain more accurate temperatures. Hot spots in shocked polymer-encased HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) crystals are observed in real-time, showing a hot spot produced in a collapsing void that ignites a deflagration. Despite the small dimensions of our explosive charges (typically 1 mm diameter and 250 μm length), we produced reproducible detonation states in solid and liquid explosives using short-duration shocks near the von Neumann spike (VNS) pressure. We show the VNS pressure is associated with a transition to high-efficiency gas production from the explosives. In studies of NM, prior to detonation, we see reaction originating at hot spots which coalesce to form a superdetonation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2005

Visible-Near Infrared Imaging Spectrometer Data of Explosion Craters

In a continuing study to capture a realistic terrain applicable to studies of cratering processes and landing hazards on Mars, we have obtained new high resolution visible-near infrared images of several explosion craters at the Nevada Test Site. We used the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) to obtain images in 224 spectral bands from 0.4-2.5 microns [1]. The main craters that were imaged were Sedan, Scooter, Schooner, Buggy, and Danny Boy [2]. The 390 m diameter Sedan crater, located on Yucca Flat, is the largest and freshest explosion crater on Earth that was formed under conditions similar to hypervelocity impact cratering. As such, it is effectively pristine, having been formed in 1962 as a result of the detonation of a 104 kiloton thermonuclear device, buried at the appropriate equivalent depth of burst required to make a "simple" crater [2]. Sedan was formed in alluvium of mixed lithology [3] and subsequently studied using a variety of field-based methods. Nearby secondary craters were also formed at the time and were also imaged by AVIRIS. Adjacent to Sedan and also in alluvium is Scooter, about 90 m in diameter and formed by a high-explosive event. Schooner (240 m) and Danny Boy (80 m, Fig. 1) craters were also important targets for AVIRIS as they were excavated in hard welded tuff and basaltic andesite, respectively [3, 4]. This variation in targets will allow the study of ejecta patterns, compositional modifications due to the explosions, and the role of craters as subsurface probes.

Farr, T. G.↗
DOE OSTI2018

Shock-induced reaction synthesis of cubic boron nitride

Here, we report ultra-fast (0.1–5 μs) shock-induced reactions in the 3B-TiN system, leading to the direct synthesis of cubic boron nitride, which is extremely rare in nature and is the second hardest material known. Composite powders were produced through high-energy ball milling to provide intimate mixing and subsequently shocked using an explosive charge. High-resolution transmission electron microscopy and X-ray diffraction confirm the formation of nanocrystalline grains of c-BN produced during the metathetical reaction between boron and titanium nitride. Our results illustrate the possibility of rapid reactions enabled by high-energy ball milling possibly occurring in the solid state on incredibly short timescales. This process may provide a route for the discovery and fabrication of advanced compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗