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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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156 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Preliminary Experimental Investigation of Multi-Shock Shield Performance Against Meteoritic Other Lithic Projectiles

The protection capabilities of micrometeoroid and orbital debris (MMOD) shields are invariably linked to the physical properties of the impactor. Regardless of the shield type, or bumper material employed, the general principles of purposefully designed multi-walled MMOD protection relies on the ability to disrupt, shock, melt, and/or vaporize the projectile before it interacts with a critical spacecraft component. Here, we begin to study the influence of projectile heterogeneity on the performance of multi-shock shields by conducting hypervelocity impact tests using meteorite and a variety of other rock-like (i.e., lithic) materials. Testing was conducted using a .17 caliber two-stage light-gas gun, launching cylindrical lithic projectiles between 5.66 and 7.06 km/s. Shield layups included three layers of Nextel and one layer of graphite composite as a rear wall, with each layer having a 35 mm standoff. After testing a comparison of rear wall and witness plate damage was made to separate tests conducted using spherical Al projectiles of similar mass. It was observed that the more heterogenous meteorite projectile gave rise to notably more damage to the witness plate than an Al projectile of equivalent mass, while the other, more homogeneous lithic projectiles, did not.

meteorite↗
DOE OSTI2021

Dynamic Properties of FeCrMnNi, a High Entropy Alloy

High entropy alloys (HEAs) represent a new class of materials that potentially possess an ideal combination of high strength and ductility and may be candidate materials that can withstand high amounts of damage before failure, especially under extreme conditions. To this end, a series of shock/spall loading experiments were conducted on an Fe/Cr/Mn/Ni HEA to assess not only its equation of state (EOS) but also its resistance to damage and failure. A single-stage light gas gun was used to conduct a series of flyer plate symmetric impact experiments coupled with recovery of the samples for post-mortem microstructural analysis to obtain fundamental understanding regarding the damage morphology. Our results show that the measured EOS for this alloy was in reasonable agreement with an estimated Hugoniot value. Additionally, the spall strength of these alloys was found to vary between 1.4 and 1.9 GPa within the same plate but was comparable to other iron-based conventional alloys. DOE/NV/03624--1059

36 MATERIALS SCIENCE↗
DOE OSTI2020

Imaging perturbed shock propagation in powders

A novel experimental methodology is presented to study the deviatoric response of powders in shock regimes. The powders are confined to a cylindrical wedge volume, and a projectile-driven shock wave with a sinusoidally varying front propagates through the powder. The perturbed shock wave exhibits a damping behavior due to irreversible processes of viscosity and strength (deviatoric) of the powder with propagation through increasing powder thicknesses. The inclined surface of the wedge is polished and coated to establish a diffuse surface suitable for reflecting incident laser light into a high-speed camera imaging at 5 MHz. Images of the contrast loss upon shock wave arrival at the observation surface are post-processed for qualitative and quantitative information. New data of shock damping behavior with parameters of perturbation wavelength and initial shock strength are presented for powders of copper, tantalum, and tungsten carbide as well as their mixtures. We present the first full-field images showing additional spatial disturbances on the perturbed shock front that appear dependent on particle material and morphology.

47 OTHER INSTRUMENTATION↗
NASA NTRS2020

LGGUN User's Manual

LGGUN is a quasi-one-dimensional Godunov code1 which is second order accurate in time and third order accurate in space, uses realistic equations of state for all media, includes wall friction and heat transfer for all gas and dense media zones and includes a simple non-equilibrium model for gas phase turbulence. This manual details the theory and operation of the code.

Ballistic Range↗
NASA NTRS2016

The Ames Vertical Gun Range

The Ames Vertical Gun Range (AVGR) is a national facility for conducting laboratory- scale investigations of high-speed impact processes. It provides a set of light-gas, powder, and compressed gas guns capable of accelerating projectiles to speeds up to 7 km s(exp -1). The AVGR has a unique capability to vary the angle between the projectile-launch and gravity vectors between 0 and 90 deg. The target resides in a large chamber (diameter approximately 2.5 m) that can be held at vacuum or filled with an experiment-specific atmosphere. The chamber provides a number of viewing ports and feed-throughs for data, power, and fluids. Impacts are observed via high-speed digital cameras along with investigation-specific instrumentation, such as spectrometers. Use of the range is available via grant proposals through any Planetary Science Research Program element of the NASA Research Opportunities in Space and Earth Sciences (ROSES) calls. Exploratory experiments (one to two days) are additionally possible in order to develop a new proposal.

The chamber provides a number of viewing ports and↗
DOE OSTI2021

Recent progress in shattered pellet injection technology in support of the ITER disruption mitigation system*

Shattered pellet injection (SPI) has been selected as the baseline technology for the disruption mitigation (DM) system for ITER. Typical SPI utilizes cryogenic cooling to desublimate low pressure (<100 mbar) gases onto a cold zone within a pipe gun barrel, forming a cylindrical pellet. Pellets are dislodged from the barrel and accelerated using either a gas driven mechanical punch or high-pressure light-gas delivered by a fast-opening valve. SPI technology developed at Oak Ridge National Laboratory is currently deployed and operational on DIII-D, JET, and KSTAR. These SPI systems are used in experiments for physics scaling to ITER thermal mitigation and runaway electron dissipation/avoidance. The pellet sizes used for these machines are in the range of 4 to 12.5 mm in diameter with length to diameter ratios (L/D) of ~1.5. The current plan for ITER SPI is to utilize pellets that are 28.5 mm in diameter with an L/D of ~2. Furthermore, the large pellet sizes, high steady-state magnetic fields, and limitations of operating in a radiation environment render much of the current technology unusable. In addition to technology improvements, a deeper understanding of pellet material properties, formation, and release is being developed for implementation in future SPI designs, specifically ITER.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1982

Plasma Spray for Difficult-To-Braze Alloys

Nickel plating on surfaces makes brazing easier for some alloys. Sometimes nickel plating may not be feasible because of manufacturing sequence, size of hardware, or lack of suitable source for nickel plating. Alternative surface preparation in such cases is to grit-blast surface lightly and then plasma-spray 1 1/2 to 2 mils of fine nickel powder or braze-alloy material directly on surface. Powder is sprayed from plasma gun, using argon as carrier gas to prevent oxidation of nickel or braze alloy.

Brennan, A.↗
DOE OSTI2020

Femtosecond X-ray Diffraction of Laser-shocked Forsterite (Mg 2 SiO 4 ) to 122 GPa

The response of forsterite, Mg 2 SiO 4 , under dynamic compression is of fundamental importance for understanding its phase transformations and high-pressure behavior. Here, we have carried out an in situ X-ray diffraction study of laser-shocked polycrystalline and single-crystal forsterite from 19 to 122 GPa using the Matter in Extreme Conditions end-station of the Linac Coherent Light Source. Under laser-based shock loading, forsterite does not transform to the high-pressure equilibrium assemblage of MgSiO 3 bridgmanite and MgO periclase, as has been suggested previously. Instead, we observe forsterite and forsterite III, a metastable polymorph of Mg 2 SiO 4 , coexisting in a mixed-phase region from 33 to 75 GPa for both polycrystalline and single-crystal samples. Densities inferred from X-ray diffraction are consistent with earlier gas-gun shock data. At higher stress, the response is sample-dependent. Polycrystalline samples undergo amorphization above 79 GPa. For [010]- and [001]-oriented crystals, a mixture of crystalline and amorphous material is observed to 108 GPa, whereas the [100]-oriented forsterite adopts an unknown phase at 122 GPa. The first two sharp diffraction peaks of amorphous Mg 2 SiO 4 show a similar trend with compression as those observed for MgSiO 3 in both recent static- and laser-driven shock experiments. This study provides new insight into the transformation of forsterite under nanosecond-duration shock loading. This work emphasizes the importance of formation of metastable phases along the Hugoniot and adds to evidence that the 300-K single-crystal diamond anvil cell experiments have relevance for understanding structures formed under shock compression. In particular, the metastable phase forsterite III has now been shown to form under dynamic compression from 10s to 100s of nanoseconds as well as under 300-K static compression. Upon compression to higher pressures, Mg 2 SiO 4 transforms to an amorphous phase. These results have broad relevance for understanding the behavior of silicates under dynamic compression.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Phase Transitions in (Mg,Fe) 2 SiO 4 Olivine under Shock Compression

The response of forsterite, Mg 2 SiO 4 , under dynamic compression is of fundamental importance for understanding its phase transformations and high-pressure behavior. Here, we have carried out an in situ X-ray diffraction study of laser-shocked polycrystalline and single-crystal forsterite from 19 to 122 GPa using the Matter in Extreme Conditions end-station of the Linac Coherent Light Source. Under laser-based shock loading, forsterite does not transform to the high-pressure equilibrium assemblage of MgSiO 3 bridgmanite and MgO periclase, as has been suggested previously. Instead, we observe forsterite and forsterite III, a metastable polymorph of Mg 2 SiO 4 , coexisting in a mixed-phase region from 33 to 75 GPa for both polycrystalline and single-crystal samples. Densities inferred from X-ray diffraction are consistent with earlier gas-gun shock data. At higher stress, the response is sample-dependent. Polycrystalline samples undergo amorphization above 79 GPa. For [010]- and [001]-oriented crystals, a mixture of crystalline and amorphous material is observed to 108 GPa, whereas the [100]-oriented forsterite adopts an unknown phase at 122 GPa. The first two sharp diffraction peaks of amorphous Mg 2 SiO 4 show a similar trend with compression as those observed for MgSiO 3 in both recent static- and laser-driven shock experiments. This study provides new insight into the transformation of forsterite under nanosecond-duration shock loading. This work emphasizes the importance of formation of metastable phases along the Hugoniot and adds to evidence that the 300-K single-crystal diamond anvil cell experiments have relevance for understanding structures formed under shock compression. In particular, the metastable phase forsterite III has now been shown to form under dynamic compression from 10s to 100s of nanoseconds as well as under 300-K static compression. Upon compression to higher pressures, Mg 2 SiO 4 transforms to an amorphous phase. These results have broad relevance for understanding the behavior of silicates under dynamic compression.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Design, development and commissioning of a multi-alkali semiconductor photocathode deposition system for the IUAC Delhi light source photoinjector

A fourth-generation light source, called Delhi Light Source (DLS) based on photocathode-based RF gun has been commissioned at Inter-University Accelerator Centre, New Delhi. Presently, the electron beam is being generated from copper photocathode and the beam is being used for scheduled experiments. Soon, the semiconductor photocathode will be used to produce higher beam current. Here, to develop the semiconductor photocathode, a dedicated photocathode deposition facility was developed in collaboration with Brookhaven national Laboratory (BNL) and has been successfully commissioned and becomes operational at IUAC. This deposition facility is an integrated system with the electron gun and is a unique system as it is capable of producing, preserving (without residual gas poisoning) and in-vacuum transfer of the deposited photocathodes from the deposition chamber up to the RF electron gun. The system is designed to operate under ultra-high vacuum (UHV) and is equipped with load-lock chambers, substrate heating assembly, thickness monitoring via a quartz crystal microbalance (QCM), and an in-situ setup for quantum efficiency (QE) measurements. After testing of all the subsystems and a detailed calibration, the first deposition of a cesium telluride (Cs 2 Te) photocathode was successfully performed on a copper (Cu) substrate. This successful commissioning and initial deposition mark a significant step toward the indigenous photocathode development and lays the groundwork for further research into advanced photo emissive materials at IUAC. This paper will discuss the salient features, installation, commissioning, first semiconductor photocathode deposition and its results.

47 OTHER INSTRUMENTATION↗