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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Observations of Herbig Ae/Be Stars with Herschel/PACS: The Atomic and Molecular Contents of Their Protoplanetary Discs

We observed a sample of 20 representative Herbig Ae/Be stars and 5 A-type debris discs with PACS onboard Herschel, as part of the GAS in Protoplanetary Systems (GASPS) project. The observations were done in spectroscopic mode, and cover the far-infrared lines of [OI], [CII], CO, CH+, H20, and OH. We have a [OI]63 micro/ detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. The [OI] 145 micron line is only detected in 25% and CO J = 18-17 in 45% (and fewer cases for higher J transitions) of the Herbig Ae/Be stars, while for [CII] 157 micron, we often find spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. First seen in HD 100546, CH+ emission is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and either the stellar or disc parameters, such as stellar luminosity, ultraviolet and X-ray flux. accretion rate, polycyclic aromatic hydrocarbon (PAH) band strength, and flaring. We find that the stellar ultraviolet flux is the dominant excitation mechanism of [OI] 63 micron, with the highest line fluxes being found in objects with a large amount of flaring and among the largest PAH strengths. Neither the amount of accretion nor the X-ray luminosity has an influence on the line strength. We find correlations between the line flux of [OI]63 micron and [OI] 145 micron, CO J = IS-17 and [OI] 6300 A, and between the continuum flux at 63 micron and at 1.3 mm, while we find weak correlations between the line flux. of [OI] 63 micron and the PAH luminosity, the line flux of CO J = 3-2, the continuum flux at 63 pm, the stellar effective temperature, and the Br-gamma luminosity. Finally, we use a combination of the [OI] 63 micron and C(12)O J = 2-1 line fluxes to obtain order of magnitude estimates of the disc gas masses, in agreement with the values that we find from detailed modelling of two Herbig Ae/Be stars, HD 163296 and HD 169142.

Meeus, G.↗
NASA NTRS1993

Computational flow predictions for hypersonic drag devices

The effectiveness of two types of hypersonic decelerators is examined: mechanically deployable flares and inflatable ballutes. Computational fluid dynamics (CFD) is used to predict the flowfield around a solid rocket motor (SRM) with a deployed decelerator. The computations are performed with an ideal gas solver using an effective specific heat ratio of 1.15. The results from the ideal gas solver are compared to computational results from a thermochemical nonequilibrium solver. The surface pressure coefficient, the drag, and the extend of the compression corner separation zone predicted by the ideal gas solver compare well with those predicted by the nonequilibrium solver. The ideal gas solver is computationally inexpensive and is shown to be well suited for preliminary design studies. The computed solutions are used to determine the size and shape of the decelerator that are required to achieve a drag coefficient of 5. Heat transfer rates to the SRM and the decelerators are predicted to estimate the amount of thermal protection required.

Tokarcik, Susan A.↗
NASA NTRS2000

Overview of the Solar Ultraviolet Magnetograph Investigation

Traditional magnetographs measure the solar magnetic field at the visible "surface" of the Sun, the photosphere. The Solar Ultraviolet Magnetograph Investigation (SUMI) is a design study for an instrument to measure the solar magnetic field higher in the atmosphere, in the upper chromosphere and in the transition region at the base of the corona. The magnetic pressure at these levels is much stronger than the gas pressure (in contrast to the situation at the photosphere), and so the field is much more dynamic. Observations in this region will significantly improve our understanding of the physical processes driving flares and heating in the Sun's upper atmosphere. The instrument will incorporate new technologies to achieve the polarization efficiencies required to isolate the magnetic lines (Civ at 155nm and MgII at 280nm) to be observed in the UV. We describe the scientific goals, the SUMI baseline design and the optical components that are being developed for a sounding rocket program.

West, Edward A.↗
NASA NTRS1974

Decameter type IV bursts associated with coronal transients

The characteristics of four moving type IV burst observed with a 65- to 20-MHz swept-frequency interferometer are discussed. All four bursts were associated with depletions in the electron content of the white light corona. Characteristics of the bursts are not unique i.e., they differ in source size, structure, duration, and their association with other radio bursts. Following Smerd and Dulk (1971), it is assumed that a shock wave, moving out from the flare site is responsible for the expansion of a magnetic arch or the ejection of a plasmoid which is observed as the usual type IV burst. Behind the shock wave, the compressed coronal gas moves outward, and as it expands it causes a depletion of electrons in the inner corona. After the passage of the shock wave, sometimes the coronal magnetic field structure is restored to its initial situation, as evidenced by the observation of homologous transients.

Gergely, T. E.↗
NASA NTRS1992

A complete spectral analysis of the flare of the quasar 3C 273

The 1983 quasar outburst of the source 3C 273 is investigated by studying several months of radio-frequency and UV data that represent about six decades of frequency. The data are analyzed to account for the differences inherent in various photometric systems, and adjustments are made for reddening and line emission. Individual wavelengths are delineated in light curves which indicate distinct periods of burst activity for specific wavelengths. The spectrum of the flare is characterized by a trend in which the critical wavelength evolves toward longer wavelengths as the outburst progresses. It is suggested that the data are consistent with a model of an expanding gas cloud that emits Doppler-boosted synchrotron radiation. The spectral curves, light curves, and the spectral index are of use in the analysis of similar phenomena when VLBI data of superluminal motion are incorporated.

Sadun, Alberto C.↗
NASA NTRS2022

Delaware Basin Health and Air Quality: Spatiotemporal Analysis of Air Pollutants Collected from Ground and Space Instruments Around the Guadalupe Mountains and Carlsbad Caverns National Parks

Nitrogen dioxide (NO2) is a precursor for secondary air pollutants, which are associated with decreased visibility, and decreased ecosystem and respiratory health. NO2 is a growing threat to national parks within the Delaware Basin where nearby oil and gas activity contributes to deteriorating park conditions, implying adverse effects on the local tourism economy and public health. To demonstrate spatial and temporal patterns of air pollution in the parks, we examined average monthly, seasonal, and annual tropospheric column concentrations of NO2 in Carlsbad Caverns (CAVE) and Guadalupe Mountain (GUMO) National Parks. We used both the NASA Ozone Monitoring Instrument (OMI) and the European Space Agency (ESA) Tropospheric Monitoring Instrument (TROPOMI) to map NO2 tropospheric column densities. Using ground-based emissions values from the Environmental Protection Agency National Emissions Inventory (NEI) for two nearby natural gas processing plants (Indian Basin Gas Plant, South Carlsbad Plant), we extrapolated monthly trends from these point sources and compared seasonal emissions levels with the measurements recorded by OMI and TROPOMI. The NEI data show an 8% increase in flaring from 2013–2021. OMI measured a 38.3% NO2 increase over the Delaware Basin, 15.29% increase over CAVE, and 4.26% decrease over GUMO from 2011–2018. TROPOMI measured a -1% NO2 change over the Delaware Basin, 3% over CAVE, and 7% over GUMO from 2018–2020. The analysis indicates a positive correlation between emissions from fossil fuel exploration and NO2 concentrations above CAVE and GUMO. This information will inform National Park Service air quality monitoring and policy efforts to ensure compliance with the Clean Air Act.

Sean Cusick↗
NASA NTRS1987

Nuclear processes and accelerated particles in solar flares

Nuclear processes and particle acceleration in solar flares are discussed and the theory of gamma-ray and neutron production is reviewed. Gamma-ray, neutron, and charged-particle observations of solar flares are compared with predictions, and the implications of these comparisons for particle energy spectra, total numbers, anisotropies, electron-to-proton ratios, and acceleration mechanisms are considered. Elemental and isotopic abundances of the ambient gas derived from gamma-ray observations have also been compared to abundances obtained from observations of escaping accelerated particles and other sources.

Ramaty, R.↗
NASA NTRS2020

A NICER View of a Highly Absorbed Flare in GRS 1915+105

After 26 yr in outburst, the black hole X-ray binary GRS 1915+105 dimmed considerably in early 2018; its flux dropped sharply in mid-2019, and it has remained faint ever since. This faint period, the "obscured state," is punctuated by occasional X-ray flares, many of which have been observed by NICER as part of our regular monitoring program. Here we present detailed time-resolved spectroscopy of one bright flare, whose spectrum shows evidence of high column density partial covering absorption and extremely deep absorption lines (equivalent widths over 100 eV in some cases). We study the time-dependent ionization of the obscuring gas with xstar, ultimately attributing the absorption to a radially stratified absorber of density ∼10^(12)–10^(13) per cu.cm at ∼few ×10^(11) cm from the black hole. We argue that a vertically extended outer disk could explain this obscuration. We discuss several scenarios to explain the obscured state, including massive outflows, an increase in the mass accretion rate, and changes in the outer disk that herald the approach of quiescence, but none are entirely satisfactory. Alternative explanations, such as obscuration by the accretion stream impact point, may be testable with current or future data.

J. Neilsen↗
NASA NTRS1981

Solar flare irradiation records in Antarctic meteorites

The observation of tracks from solar flare heavy nuclei in Antarctic meteorite samples is reported. In an analysis of nuclear track densities in eight L and H chondrites of low metamorphic grade, it was found that two interior specimens of sample 77216, an L-3 chondrite, contain olivine grains with track densities much higher than the average track densities, indicating precompaction irradiation by solar flares in different shielding conditions. Preliminary data from mass spectroscopic analyses show a large excess of noble gases, with a Ne-20/Ne-22 ratio of greater than or equal to 10, indicating the presence of solar-type noble gas. Results of track density measurements in the other Antarctic meteorites range from 10,000 to 4,000,000/sq cm, which is within the range observed in non-Antarctic L-group meteorites

Goswami, J. N.↗
NASA NTRS1992

FNAS: The magnetic configuration leading to solar flares

We present a method for solving plasma magnetohydrodynamic (MHD) problems arising from the interaction of plasmas with magnetic fields in stellar atmospheres. Our approach, in contrast to previous methods, is not based on solving equations for the magnetic field and plasma velocity but rather studies the evolution of the electric current and density (and the related gas pressure). We have applied the method to several studies involving linearized departures from static, current-free equilibria. The applications show explicit solutions for cases found in astrophysics and to problems encountered with earlier studies where the gas pressure was neglected. The method is particularly well suited for studying situations which involve a transition between high and low plasma-beta regions. It shows precisely how electric currents, and magnetic free-energy, build up in the plasma as a result of the slow stressing of a potential magnetic field configuration. The method also demonstrates how transverse-current waves, a mix of Alfven and magneto-acoustic modes, propagate in a low-beta plasma for any density stratification and background field geometry.

Fontenla, Juan M.↗
NASA NTRS1992

Great magnetic storms

The five largest magnetic storms that occurred between 1971 to 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that: (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective.

Tsurutani, Bruce T.↗
NASA NTRS1979

Solar wind heavy ions from flare-heated coronal plasma

Information concerning the coronal expansion is carried by solar-wind heavy ions. Distinctly different energy-per-charge ion spectra are found in two classes of solar wind having the low kinetic temperatures necessary for E/q resolution of the ion species. Heavy-ion spectra which can be resolved are most frequently observed in the low-speed interstream (IS) plasma found between high speed streams; the streams are thought to originate from coronal holes. Although the sources of the IS plasma are uncertain, the heavy-ion spectra found there contain identifiable peaks of O, Si, and Fe ions. Such spectra indicate that the IS ionization state of O is established in coronal gas at a temperature of approximately 1.6 million K, while that of Fe is frozen in farther out at about 1.5 million K. On occasion anomalous spectra are found outside IS flows in solar wind with abnormally depressed local kinetic temperatures. The anomalous spectra contain Fe(16+) ions, not usually found in IS flows, and the derived coronal freezing-in temperatures are significantly higher. The coronal sources of some of these ionizationally hot flows are identified as solar flares.

Bame, S. J.↗
DOE OSTI2026

INFUSE:FLARED (Final Technical Report)

This report summarizes the final outcomes of the INFUSE:FLARED collaboration between Tokamak Energy (TE), the University of Illinois Urbana-Champaign (UIUC), and the Department of Energy (DOE). The project aimed to experimentally determine and model the pumping, absorption, and separation behavior of deuterium in flowing liquid lithium under gas and plasma exposure conditions. The work supports the development of lithium-based plasma-facing components (PFCs) and tritium management strategies for next-generation fusion plants.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1976

Interplanetary disturbances in the solar wind produced by density, temperature, or velocity pulses at 0.08 AU

Time-dependent solutions of a one-fluid model of the interplanetary medium are investigated. This set of unsteady hydrodynamic equations has been written in conserved form in order to apply the Lax-Wendroff (1960) method for the solution of this problem. The initial disturbance is specified by a pulse at 0.08 AU. Physically, this pulse can be interpreted as having been caused by a solar flare, surge, or any other solar disturbance. The equilibrium condition is determined to be the steady solution of the governing equations and represents the quiet solar wind. Results are presented in terms of density, temperature, and velocity profiles of the interplanetary gas flow at heliocentric distances up to 6 AU at several times. Also, the trajectories of disturbances for various initial pulses are shown. Some June 1972 interplanetary observational data are compared with these theoretical calculations. On the basis of these results, the effects of solar disturbances on the interplanetary environment (such as the generation of large nonlinear wave trains in the shock wakes) can be inferred.

Wu, S. T.↗
NASA NTRS1980

Manufacturing process applications team (MATeam)

The objectives and activities of an aerospace technology transfer group are outlined and programs in various stages of progress are described including the orbital tube flaring device, infrared proximity sensor for robot positioning, laser stripping magnet wire, infrared imaging as welding process tracking system, carbide coating of cutting tools, nondestructive fracture toughness testing of titanium welds, portable solar system for agricultural applications, and an anerobic methane gas generator.

Bangs, E. R.↗
DOE OSTI2024

Simulations of the Collision between a Debris Stream and an Outer Dusty Torus: A Possible Channel for Forming a Fast-rise and Long-delay Radio Outburst in Tidal Disruption Events

A geometrically thick dusty torus structure is believed to exist in the nuclear regions of galaxies (especially in active galactic nuclei). The debris stream from a tidal disruption event (TDE) will possibly collide with the dusty torus and produce a transient flare. We perform three-dimensional hydrodynamic simulations to model the dynamical evolution of the interaction between unbound debris and a dusty torus. During the continuous interaction, shocked material will be spilled out from the interaction region and form an outflow. We calculate the temporal evolution of synchrotron emission by assuming that the shock accelerates a fraction of electrons in the outflow into a nonthermal distribution. We find that radio emission from the debris–torus collision generates a steep-rise and slow-decline radio light curve due to the sharp edge and dense gas of the dusty torus, where the radio outburst is delayed relative to the main optical/X-ray outburst by several years or even several tens of years. We apply our model to a TDE that happened in a narrow-line Seyfert I galaxy (PS16dtm), where both the radio spectrum and the light curve can be roughly reproduced. Future high-sensitivity, wide-field-of-view radio surveys have the opportunity to detect more such radio flares.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Dynamics of Gas Bubbles From a Submarine Hydrocarbon Seep Within the Hydrate Stability Zone

We validate a new model for mass transfer and bubble transport for natural seeps on the continental margins using an integrated observation of a seep at 883 m in the Northern Gulf of Mexico. In the model, mass transfer is assumed to transition from clean to dirty bubble mass transfer rates following a characteristic hydrate formation time that depends on the initial bubble surface area and the hydrate subcooling. We show that buoyancy-induced upwelling is negligible for the bubble stream. We initialize the model using precise data observed at the seafloor and validate the model results to optical and acoustic measurements within the bubble stream. The model accurately predicts the acoustic attenuation of the bubble flare by lateral spreading and bubble shrinkage throughout the water column. In conclusion, the model shows that up to 99.4% by mass of the released gases from this seep dissolves into the ocean within the hydrate stability zone.

03 NATURAL GAS↗
DOE OSTI2023

Distributed clean energy opportunities for US oil refinery operations

The oil and gas industry is increasingly seeking operational improvements to reduce costs and emissions while improving resilience. This study describes techno-economic analysis of opportunities for distributed energy resources that could be integrated to support oil and gas companies’ economic, environmental, and energy resiliency goals. Specifically, the analysis evaluates solar photovoltaics, wind turbines, battery energy storage, landfill gas, biomass, municipal solid waste-to-energy, solar steam for process heat, combined heat and power, and electrolyzers for hydrogen production at two hypothetical refineries, one located in Louisiana and the other in southern California. These technologies could reduce the sites’ consumption of grid electricity and/or natural gas and thus can help reduce emissions. This study employs the ReOPT tool and System Advisor Model to evaluate the techno-economic potential for clean energy technologies to support refineries in achieving energy goals, including energy cost savings, resiliency, and emissions reductions. Results indicate that the associated costs of emissions reductions via several distributed clean energy technologies are competitive with other emissions reduction strategies such as energy efficiency, reducing flaring, direct carbon capture and sequestration, and markets under certain conditions. There are also cost beneficial opportunities for the use of renewable energy for refining, especially for resilience, depending on local conditions such as resources and utility costs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗