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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

First simultaneous measurement of the γ-ray and neutron emission probabilities in inverse kinematics at a heavy-ion storage ring

The probabilities for γ-ray and particle emission as a function of the excitation energy of a decaying nucleus are valuable observables for constraining the ingredients of the models that describe the deexcitation of nuclei near the particle emission threshold. These models are essential in nuclear astrophysics and applications. In this paper, we have for the first time simultaneously measured the γ-ray and neutron emission probabilities of 208 Pb. The measurement was performed in inverse kinematics at the Experimental Storage Ring (ESR) of the GSI/FAIR facility, where a 208 Pb beam interacted through the 208 Pb (p,p') reaction with a hydrogen gas jet target. Instead of detecting the γ rays and neutrons emitted by 208 Pb, we detected the heavy beamlike residues produced after γ and neutron emission. These heavy residues were fully separated by a dipole magnet of the ESR and were detected with outstanding efficiencies. The comparison of the measured probabilities with model calculations has allowed us to test and select different descriptions of the γ-ray strength function and the nuclear level density available in the literature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1974

Radio astronomy

The origins, generation, detection, and interpretation of radio signals are discussed for signals with an assumed random polarization. After defining the basic parameters, the discussion moves to such topics as synchrotron radiation, plasma effects, changes in the electron energy spectrum in the radiating regions, energy loss to ionization, bremsstrahlung, radio astronomical observations of high-energy particles, emission by energetic particles, observation of supernova remnants and pulsars, galactic background continuum radiation, and others.

Alexander, J.↗
NASA NTRS2005

Influence of Tropospheric SO2 Emissions on Particle Formation and the Stratospheric Humidity

Stratospheric water vapor plays an important role in the chemistry and radiation budget of the stratosphere. Throughout the last decades stratospheric water vapor levels have increased and several processes have been suggested to contribute to this trend. Here we present a mechanism that would link increasing anthropogenic SO2 emissions in southern and eastern Asia with an increase in stratospheric water. Trajectory studies and model simulations suggest that the SO2 increase results in the formation of more sulfuric acid aerosol particles in the upper tropical troposphere. As a consequence, more ice crystals of smaller size are formed in the tropical tropopause, which are lifted into the stratosphere more readily. Our model calculations suggest that such a mechanism could increase the amount of water that entered the stratosphere in the condensed phase by up to 0.5 ppmv from 1950-2000.

Notholt, J.↗
NASA NTRS1966

Infrared observations of Comet 1965f.

IR photometric measurement of Comet 1965f, noting absolute intensity dependence on distance from Sun, tail intensities and nature of particle emissions

INFRARED PHOTOGRAPHY↗
NASA NTRSDate not supplied

Particulate Emission and Optical Measurements in n-Heptane Low-Swirl Non-Premixed Flames at Elevated Pressures

A series of ground combustion tests conducted at elevated pressures demonstrates in-chamber optical measurements of soot emissions, combined with conventional gaseous and particle emissions sampling techniques. Utilizing a micro-radial-entry counter-swirl (MRX) burner, we successfully stabilized an n-heptane low-swirl, non-premixed spray flame across a wide range of equivalence ratios at pressures reaching 250 psia. Our optical diagnostics feature a temporally gated diffused-backlight illumination extinction imaging (DBI-EI) system, equipped with a 470-nm strobe high-intensity LED array as the illumination source, along with a line-of-sight telecentric camera. By accessing the flame tube, the pulsed DBI-EI provides illuminating optical extinction images, enabling experimental estimation of soot volume fractions within the reaction zone. This imaging technique will allow for real-time observation of soot formation dynamics occurring above the air-blast fuel injector. To further enhance our analysis, we employed simultaneous gaseous and particulate extractive diagnostics, interpreting in-flame particulate information through CO2 sampling, exhaust particle sizing, and particle counting. The processed dataset reveals a promising application of DBI-EI for propulsion emission analysis in high-pressure environments, where optical beam-steering effects can significantly impact results. This report is essential to bridging the divide between in-flame optical diagnostics and exhaust extractive measurements. By achieving an understanding of non-premixed combustion emission characteristics, we attempt to provide invaluable data for computer code validation, advancing the field of combustion research and supporting the development of cleaner, more efficient engines.

high-pressure flame↗
NASA NTRSDate not supplied

Particulate Emission and Optical Measurements in n-Heptane Low-Swirl Non-Premixed Flames at Elevated Pressures

A series of ground combustion tests conducted at elevated pressures demonstrates in-chamber optical measurements of soot emissions, combined with conventional gaseous and particle emissions sampling techniques. Utilizing a micro-radial-entry counter-swirl (MRX) burner, we successfully stabilized an n-heptane low-swirl, non-premixed spray flame across a wide range of equivalence ratios at pressures reaching 250 psia. Our optical diagnostics feature a temporally gated diffused-backlight illumination extinction imaging (DBI-EI) system, equipped with a 470-nm strobe high-intensity LED array as the illumination source, along with a line-of-sight telecentric camera. By accessing the flame tube, the pulsed DBI-EI provides illuminating optical extinction images, enabling experimental estimation of soot volume fractions within the reaction zone. This imaging technique will allow for real-time observation of soot formation dynamics occurring above the air-blast fuel injector. To further enhance our analysis, we employed simultaneous gaseous and particulate extractive diagnostics, interpreting in-flame particulate information through CO2 sampling, exhaust particle sizing, and particle counting. The processed dataset reveals a promising application of DBI-EI for propulsion emission analysis in high-pressure environments, where optical beam-steering effects can significantly impact results. This report is essential to bridging the divide between in-flame optical diagnostics and exhaust extractive measurements. By achieving an understanding of non-premixed combustion emission characteristics, we attempt to provide invaluable data for computer code validation, advancing the field of combustion research and supporting the development of cleaner, more efficient engines.

high-pressure flame↗
DOE OSTI2025

Nuclear Waste Tank Emission Contributions to Particle Size Distribution

Pollutants from anthropogenic activities including industrial processes are ubiquitous to the environment. To understand the impact from industrial aerosol on climate and human health, industrial aerosol needs to be better characterized. Here, in this study, particle number concentrations were used as a proxy for atmospheric pollutants, which include both particles and gases. Particle concentration and size distribution were measured using a scanning mobility particle sizer (SMPS) approximately 4.5 km from primary industrial areas at the Savannah River Site in Aiken, SC. Industrial areas include numerous nuclear waste storage and processing tanks. The SMPS data were divided into two groups depending on the wind direction measured onsite to categorize transport from the industrial area or from elsewhere. Industrial contributions were found to have a higher concentration of particles with sizes less than 200 nm, 859 ± 564 cm -3 , in comparison to non-industrial attributed particles, 733 ± 495 cm -3 on average from March-July 2021. For sizes larger than 200 nm, industrial and non-industrial particles have a similar concentration, 89 ± 59 cm -3 and 99 ± 61 cm -3 , with non-industrial concentrations being slightly larger. To confirm that industrial particles could travel to the sampling location, air dispersion modeling was completed for specific case studies during the sampling period. The atmospheric dispersion modeling results confirmed that particles released at the industrial areas reached the sampling location when the wind direction was favorable for transport from the industrial areas. The greater concentration of smaller-sized particles in industrial emissions has implications for typical particulate measurements (PM2.5), heath impacts, and climatological influences.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Online characterization of primary and secondary emissions of particulate matter and acidic molecules from a modern fleet of city buses

The potential impact of transitioning from conventional fossil fuel to a non-fossil-fuel vehicle fleet was investigated by measuring primary emissions via extractive sampling of bus plumes and assessing secondary mass formation using the Gothenburg Potential Aerosol Mass (Go:PAM) reactor from 76 in-use transit buses. Online chemical characterization of gaseous and particulate emissions from these buses was conducted using chemical ionization mass spectrometry (CIMS) with acetate as the reagent ion, coupled with the Filter Inlet for Gases and AEROsols (FIGAERO). Acetate reagent ion chemistry selectively ionizes acidic compounds, including organic and inorganic acids, as well as nitrated and sulfated organics. A significant reduction (48 %–98 %) in fresh particle emissions was observed in buses utilizing compressed natural gas (CNG), biodiesels like rapeseed methyl ester (RME) and hydrotreated vegetable oil (HVO), and hybrid-electric HVO (HVO HEV ) compared to diesel (DSL). However, secondary particle formation from photooxidation of emissions was substantial across all the fuel types. The median ratio of particle mass emission factors of aged to fresh emissions increased in the following order: DSL buses at 4.0, HVO buses at 6.7, HVO HEV buses at 10.5, RME buses at 10.8, and CNG buses at 84. Of the compounds that can be identified by CIMS, fresh gaseous emissions from all Euro V/EEV (Enhanced Environmentally friendly Vehicle) buses, regardless of fuel type, were dominated by nitrogen-containing compounds such as nitrous acid (HONO), nitric acid (HNO 3 ), and isocyanic acid (HNCO), alongside small monoacids (C 1 –C 3 ). Notably, the emission of nitrogen-containing compounds was lower in Euro VI buses equipped with more advanced emission control technologies. Secondary gaseous organic acids correlated strongly with gaseous HNO 3 signals (R 2 =0.85–0.99) in Go:PAM, but their moderate to weak correlations with post-photooxidation secondary particle mass suggest that they are not reliable tracers of secondary organic aerosol formation from bus exhaust. Our study highlights that non-regulated compounds and secondary pollutant formation, not currently addressed in legislation, are crucial considerations in the evaluation of environmental impacts of future fuel and engine technology shifts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1980

Interplanetary dust collected in the earth's stratosphere - The question of solar flare tracks

The negative result of a transmission electron microscope (TEM) search for solar flare tracks in 10 micron interplanetary dust particles (Flynn et al., 1978) which have been collected in the earth's stratosphere with a program of sampling initiated by Brownlee et al. (1976) has been reported previously. In this paper, it is shown that silicates in the particles record laboratory iron-ion tracks which are detectable in the TEM. The absence of tracks in the silicates could be due to track annealing on atmospheric entry, and may indicate a particle emissivity below 0.3, or that many of the particles broke up on encounter with the atmosphere. Alternatively, the lifetime of 10 micron dust particles at 1 AU could be shorter than that given by previous estimates.

Fraundorf, P.↗
DOE OSTI2026

Pre-Equilibrium De-Excitations in Neutrino-Nucleus Interactions

Pre-equilibrium de-excitation is a well-established stage of nucleon-induced nuclear reactions but has not previously been incorporated into neutrino event generators. This work implements the Koning-Duijvestijn exciton model within the MARLEY neutrino event generator to simulate energy redistribution and particle emission before compound nucleus equilibrium. The implementation includes modular calculations of particle-hole state densities, internal transition rates, emission rates, and Monte Carlo cascade sampling, and is validated against the TALYS-2.2 nuclear reaction code. A new event record is also proposed to enable future uncertainty reweighting studies. This work establishes the first framework for studying pre-equilibrium effects in neutrino-induced reactions, with the goal of improving predictions of particle multiplicities, γ-ray production, and MeV-scale detector signals relevant to experiments such as DUNE.

Visser, Erin [Michigan State U., East Lansing (mai↗
NASA NTRS1973

Solar flare emissions and geophysical disturbances

Various geophysical phenomena are produced by both wave and particle emissions from solar flares. Using the observed data for these emissions, a review is given on the nature of solar flares and their development. Geophysical phenomena are discussed by referring to the results for solar flare phenomena.

Sakurai, K.↗
NASA NTRS1974

Solar flare emissions and geophysical disturbances

Various geophysical phenomena are produced by both wave and particle emission from solar flares. In understanding these phenomena, it is necessary to investigate the nature of these emissions and solar flare phenomena. Using the observed data for these emissions, a review is given on the nature of solar flares and their development. Geophysical phenomena are discussed by referring to the results for solar flare phenomena.

Sakurai, K.↗
NASA NTRS1979

Flyby- and rendezvous-type comet missions from the standpoint of large-particle dust experiments

The measurement by cometary flyby and rendezvous missions of the dust particles emitted from a cometary nucleus and believed to be the major source of the interplanetary dust is considered. The impact rate per unit area of particles in a given size range on a spacecraft dust sensor is calculated in terms of the distance between comet and probe and the particle emission rate and velocity. It is concluded that large-particle (greater than 100-micron) dust analysis experiments cannot be conducted on flyby missions to short-period comets since the required miss distance is orders of magnitude smaller than the targeting error, while for a rendezvous mission much greater miss distances are possible due to the longer period of cometary contact. The problem of designing dust sensors to operate at the subkilometer per second intercept velocities of a rendezvous mission is also noted.

Sekanina, Z.↗
NASA NTRS2006

Workshop on the Impacts of Aviation on Climate Change

Projections indicate that demand for aviation transportation will increase by more than two fold over the next few decades. Timely action is needed to understand and quantify the potential climate impacts of aviation emissions particularly given the sustained lapse over the last several years in U.S. research activities in this area. In response to the stated needs, a group of international experts participated in the Workshop on the Impacts of Aviation on Climate Change during June 7-9, 2006 in Boston, MA. The workshop focus was on the impacts of subsonic aircraft emissions in the UT/LS region and on the potential response of the climate system. The goals of the workshop were to assess and document the present state of scientific knowledge, to identify the key underlying uncertainties and gaps, to identify ongoing and further research needed, to explore the development of climate impact metrics, and to help focus the scientific community on the aviation-climate change research needs. The workshop concluded that the major ways that aviation can affect climate, in agreement with the 1999 assessment by the Intergovernmental Panel on Climate Change (IPCC), are the direct climate effects from CO2 and water vapor emissions, the indirect forcing on climate resulting from changes in the distributions and concentrations of ozone and methane as a primary consequence of aircraft nitrogen oxide (NOx) emissions, the direct effects (and indirect effects on clouds) from emitted aerosols and aerosol precursors, and the climate effects associated with contrails and cirrus cloud formation. The workshop was organized in three subgroups: (1) Effects of aircraft emissions on the UT/LS chemical composition, (2) Effects of water and particle emissions on contrails and on cirrus clouds, and (3) Impacts on climate from aircraft emissions and identification of suitable metrics to measure these impacts. The workshop participants acknowledged the need for focused research specifically to address the uncertainties and gaps in our understanding of current and projected impacts of aviation on climate and to develop metrics to better characterize these impacts. This may entail coordination and/or expansion of existing and planned climate research programs, or new activities. Such efforts should include strong and continuing interactions among the science and aviation communities as well as policymakers to develop well-informed decisions.

Wuebbles, Don↗