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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Infinite order sudden approximation for rotational energy transfer in gaseous mixtures

Rotational energy transfer in gaseous mixtures is analyzed within the framework of the infinite order sudden (IOS) approximation, and a new derivation of the IOS from the coupled states Lippman-Schwinger equation is presented. This approach shows the relation between the IOS and coupled state T matrices. The general IOS effective cross section can be factored into a finite sum of 'spectroscopic coefficients' and 'dynamical coefficients'. The evaluation of these coefficients is considered. Pressure broadening for the systems HD-He, HCl-He, CO-He, HCl-Ar, and CO2-Ar is calculated, and results based on the IOS approximation are compared with coupled state results. The IOS approximation is found to be very accurate whenever the rotor spacings are small compared to the kinetic energy, provided closed channels do not play too great a role.

Goldflam, R.↗
NASA NTRS1985

Total electron scattering cross sections. I - He, Ne, Ar, Xe

The apparatus and experimental procedures used to obtain total electron scattering cross sections are described, and results are presented for He, Ne, Ar and Xe in the 4-300 eV incident energy range, together with statistical errors. The results are generally found to be in good agreement with previous data except at low impact energies. Serious discrepancies remain in Xe below 20 eV impact energy.

Nickel, J. C.↗
NASA NTRS1997

The solar minimum X2.6/1B flare and CME of 9 July 1996: Solar data - Pt. 1

The solar observations from GOES-8, the Solar and Heliospheric Observatory (SOHO), and the Yohkoh satellite concerning the events of the X-class flare are discussed. The Michelson Doppler imager (MDI) magnetometer shows a new region of magnetic activity in AR 7978. The rapid development and evolution of this region is shown by the MDI and the extreme-ultraviolet Doppler telescope (EDT) data. The coronal mass ejections (CMEs) observed using coronagraphs are presented. The possible association between the CME and the X-flare is considered.

Andrews, M. D.↗
NASA NTRS2003

Geochemistry and Impact History at the Apollo 16 Landing Site

Lunar impact glasses possess the unmodified refractory element ratios of the original fused target materials at the sites of impacts. These target materials are usually regolith. 866 glasses from the Apollo 16 landing site have been analyzed by electron microprobe in this study. These glasses show significant variation and hint at the existence of highland basalt (HB) regolith compositions atypical of the usual HB compositions historically found at the Apollo 16 site. Additionally, a large number of mare glasses have been identified. Clementine color image data have been used to construct iron, titanium, and aluminum maps for comparison with the sample database. These maps suggest that the Apollo 16 landing site is largely composed of anorthositic material and that mare compositions are not found close by. Nine of these impact glasses have been dated by the Ar-40/Ar-39 technique and may be used to constrain the impact history at the Apollo 16 landing site. These results illustrate how lunar impact glasses together with orbital data can provide geochemical constraints on the local and regional geology of the Moon.

Zellner, N. E. B.↗
NASA NTRS1989

Navier-Stokes analysis of cold scramjet-afterbody flows

The progress of two efforts in coding solutions of Navier-Stokes equations is summarized. The first effort concerns a 3-D space marching parabolized Navier-Stokes (PNS) code being modified to compute the supersonic mixing flow through an internal/external expansion nozzle with multicomponent gases. The 3-D PNS equations, coupled with a set of species continuity equations, are solved using an implicit finite difference scheme. The completed work is summarized and includes code modifications for four chemical species, computing the flow upstream of the upper cowl for a theoretical air mixture, developing an initial plane solution for the inner nozzle region, and computing the flow inside the nozzle for both a N2/O2 mixture and a Freon-12/Ar mixture, and plotting density-pressure contours for the inner nozzle region. The second effort concerns a full Navier-Stokes code. The species continuity equations account for the diffusion of multiple gases. This 3-D explicit afterbody code has the ability to use high order numerical integration schemes such as the 4th order MacCormack, and the Gottlieb-MacCormack schemes. Changes to the work are listed and include, but are not limited to: (1) internal/external flow capability; (2) new treatments of the cowl wall boundary conditions and relaxed computations around the cowl region and cowl tip; (3) the entering of the thermodynamic and transport properties of Freon-12, Ar, O, and N; (4) modification to the Baldwin-Lomax turbulence model to account for turbulent eddies generated by cowl walls inside and external to the nozzle; and (5) adopting a relaxation formula to account for the turbulence in the mixing shear layer.

Baysal, Oktay↗
DOE OSTI2023

Plastic Laminate Antireflective Coatings for Millimeter-Wave Optics in BICEP Array

The BICEP/Keck series of experiments target the cosmic microwave background at degree-scale resolution from the South Pole. Over the next few years, the “Stage-3” BICEP Array (BA) telescope will improve the program’s frequency coverage and sensitivity to primordial B-mode polarization by an order of magnitude. The first receiver in the array, BA1, began observing at 30/40 GHz in early 2020. The next two receivers, BA2 and BA3, are currently being assembled and will map the southern sky at frequencies ranging from 95 to 150 GHz. Common to all BA receivers is a refractive, on-axis, cryogenic optical design that focuses microwave radiation onto a focal plane populated with antenna-coupled bolometers. High-performance antireflective coatings up to 760 mm in aperture are needed for each element in the optical chain, and must withstand repeated thermal cycles down to 4 K. Here, in this work, we present the design and fabrication of the 30/40 GHz anti-reflection coatings for the recently deployed BA1 receiver, with indices matched to its various polyethylene, nylon and alumina optical components. We describe an epoxy coating technique designed for alumina optics, which achieves better than 80% transmission at room temperature. For polyethylene optical elements, we present a new heat-compression approach that allows low-density polytetrafluoroethylene AR layers to reach sub-percent reflected power. We describe the planned use of these methods for the next BA cryostats, which may inform technological choices for future small-aperture telescopes of the CMB-S4 experiment.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Distribution of Antibiotic Resistance in a Mixed-Use Watershed and the Impact of Wastewater Treatment Plants on Antibiotic Resistance in Surface Water

The aquatic environment has been recognized as a source of antibiotic resistance (AR) that factors into the One Health approach to combat AR. To provide much needed data on AR in the environment, a comprehensive survey of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues was conducted in a mixed-use watershed and wastewater treatment plants (WWTPs) within the watershed to evaluate these contaminants in surface water. A culture-based approach was used to determine prevalence and diversity of ARB in surface water. Low levels of AR Salmonella (9.6%) and Escherichia coli (6.5%) were detected, while all Enterococcus were resistant to at least one tested antibiotic. Fewer than 20% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (17.3%) and carbapenem-resistant Enterobacteriaceae (CRE) (7.7%) were recovered. Six ARGs were detected using qPCR, primarily the erythromycin-resistance gene, ermB. Of the 26 antibiotics measured, almost all water samples (98.7%) had detectable levels of antibiotics. Analysis of wastewater samples from three WWTPs showed that WWTPs did not completely remove AR contaminants. ARGs and antibiotics were detected in all the WWTP effluent discharges, indicating that WWTPs are the source of AR contaminants in receiving water. However, no significant difference in ARGs and antibiotics between the upstream and downstream water suggests that there are other sources of AR contamination. The widespread occurrence and abundance of medically important antibiotics, bacteria resistant to antibiotics used for human and veterinary purposes, and the genes associated with resistance to these antibiotics, may potentially pose risks to the local populations exposed to these water sources.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1975

Local time variation of equatorial thermospheric composition determined by the San Marco 3 Nace

The results of the Neutral Atmospheric Composition Experiment (Nace) on the Italian San Marco 3 satellite are analyzed. The analysis provides a comprehensive description of the daily variations in the densities of O, N2, Ar, and He in composition of the lower thermosphere, and also indicates that transport processes (possibly occurring elsewhere in the atmosphere) play an important part in the daily variation of the thermospheric composition at altitudes between 220 and 250 km.

Newton, G. P.↗
NASA NTRS1982

High-temperature ceramic heat exchanger element for a solar thermal receiver

A study was performed by AiResearch Manufacturing Company, a division of The Garrett Corporation, on the development a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by an innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F ar at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver has been completed.

Strumpf, H. J.↗
NASA NTRS1972

Rare gas studies of the galactic cosmic ray irradiation history of lunar rocks.

Average irradiation depths and exposure ages of Tranquillity Base rocks are computed on the basis of eight analyses of the five noble gases in whole rock samples and lunar separates from lunar rocks, in conjunction with available literature data. Correlated variations in He-3/Ne-21 and Ar-38/Ne-21 reflect shielding differences. This correlation cannot be explained by diffusion losses, even though evidence for gas loss is obtained from mineral separate data. A qualitative shielding sequence is constructed which agrees reasonably well with the sequence based on Gd isotopic data.

Huneke, J. C.↗
NASA NTRS1978

Growth, evaluation and modeling of silicon-on-ceramic solar cells

The silicon-on-ceramic (SOC) process uses inexpensive ceramic substrates to provide supported growth of silicon from the melt. The conditions for unidirectional solidification, the grain structure and other properties are quite similar to those of EFG silicon ribbon. Solar cells with interdigital electrodes have demonstrated AMl conversion efficiencies (active area) of 7.8% without AR coatings and 10.1% efficiencies with an AR coating of SiO. Mathematical modeling of the series resistance of cells shows the feasibility of making electrical contact to the base layer of the cell through slots in the substrate. However, series resistance in the base layer sets an upper limit on slot spacing for efficient cell performance.

Zook, J. D.↗
NASA NTRS1982

Shock disturbance of the I-Xe system

Three separate samples of the meteorite Bjurbole were artificially shocked at pressures of 70 kb, 200 kb, and 400 kb. Analysis of xenon released in stepwise heating shows that the I-Xe system of the 400 kb sample is substantially altered by the shock loading, and it is no longer possible to infer an age or trapped xenon composition for that sample. The 200-kb and 70-kb samples display isotopic structures progressively less altered demonstrating the gradations in shock disturbance likely to be found in natural systems. Interpretations of the I-Xe and Ar-40-Ar-39 systems for several naturally shocked meteorites are also presented. New data for Arapahoe do not confirm the previously reported age and trapped xenon composition, demonstrating instead that its I-Xe structure has been strongly disturbed by shock.

Caffee, M. W.↗
NASA NTRS1993

High-performance visible/UV CCD focal plane technology for spacebased applications

We describe recent technology developments aimed at large CCD imagers for space based applications in the visible and UV. Some of the principal areas of effort include work on reducing device degradation in the natural space-radiation environment, improvements in quantum efficiency in the visible and UV, and larger-device formats. One of the most serious hazards for space based CCD's operating at low signal levels is the displacement damage resulting from bombardment by energetic protons. Such damage degrades charge-transfer efficiency and increases dark current. We have achieved improved hardness to proton-induced displacement damage by selective ion implants into the CCD channel and by reduced temperature of operation. To attain high quantum efficiency across the visible and UV we have developed a technology for back-illuminated CCD's. With suitable antireflection (AR) coatings such devices have quantum efficiencies near 90 percent in the 500-700-nm band. In the UV band from 200 to 400 nm, where it is difficult to find coatings that are sufficiently transparent and can provide good matching to the high refractive index of silicon, we have been able to substantially increase the quantum efficiency using a thin film of HfO2 as an AR coating. These technology efforts were applied to a 420 x 420-pixel frame-transfer imager, and future work will be extended to a 1024 x 1024-pixel device now under development.

Burke, B. E.↗
NASA NTRS1993

Rhenium-osmium isotope systematics of Group 2A and Group 4A iron meteorites

We are investigating the Re-Os isotope systematics of two groups of magmatic iron meteorites (2A, 4A) in an attempt to establish precise 'total rock' isochrons by the Re-Os system. The Re-187/Os-187 isotope system is recognized as a method by which the ages of iron meteorites can be directly determined and that can provide information on the timing of FeNi segregation and core formation in planetesimals. The Re-Os isotope system permits the direct absolute dating of the metal phase in iron meteorites. Indirect dating of iron meteorites has been achieved in the past through the Rb-Sr, K-Ar, and most recently, Sm-Nd for silicate inclusions, where present. Relative dating has been obtained directly by extensive studies of the short-lived system Pd-107/Ag-107 for the metal and sulfide phases and indirectly using I-129/Xe-129 in silicate and sulfide inclusions.

Creaser, R. A.↗
NASA NTRS1974

Mare basalts from the Taurus-Littrow region of the moon

Two distinct chemical basalt types have been sampled at the Apollo 17 landing site. Very high-titanium basalts (about 13 wt % TiO2) are the dominant type and display a textural range from olivine-porphyritic, ilmenite vitrophyres to plagioclase-poikilitic, ilmenite microgabbros. Most of these rocks could have come from one flow. These basalts appear to represent partial melts from feldspar-ilmenite cumulates with an Ar-40/Ar-39 age of about 3.7 G.y., which have experienced little, if any, near-surface fractionation of olivine and Fe-Mg-Ti oxides. A second type of basalt virtually identical to the Apollo 11 (low-K) basalts is much less common.

Papike, J. J.↗
NASA NTRS1978

Ar-39-Ar-40 and petrologic study of Luna 24 samples 24077,13 and 24077,63

The ferrogabbro 24077,13, with pyroxene and plagioclase major and minor element chemical ranges comparable to the dominant ferrogabbro component in the Luna 24 core, has a Ar-39-Ar-40 temperature release age of 3.33 plus or minus 0.21 billion years. The metaferrobasalt 24077,63 is very fine-grained with a texture and mineralogy consistent with contact metamorphism between superimposed basalt flows or within a single flow. The Ar-39-Ar-40 plateau age of 24077,63 is 3.26 plus or minus 0.4 billion years. The basalt flows in Mare Crisium are about the same age as those of Mare Imbrium and younger than those of Mare Tranquillitatis and Mare Serenitatis.

Schaeffer, O. A.↗
NASA NTRS1982

An integrated regenerative air revitalization system for spacecraft

Progress towards development of an air revitalization system (ARS) for spacecraft breathable atmosphere regeneration is assessed, and a preliminary design for a one-person ARS is described. The ARS is considered a necessary component of any permanently manned orbital station, and studies have demonstrated that penalties for expendable air supplies justify an ARS for missions longer than 40 days. CO2 must be removed and O2 returned along with N2, which can be extracted from hydrazine, with the H2 component returning to the operation of the CO2 reduction subsystem. An experimental ARS (ARX-1) features a cabin humidity control unit, a CO2 concentrator, an air-cooled CO2 reduction reactor, an oxygen generator (electrolysis), the hydrazine N2 generator, and a water handling unit. A 120-day test demonstrated one-button startup and 480 hr operation in a normal mode.

Noyes, G. P.↗