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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 91 records · Page 5
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NASA NTRSDate not supplied

Particle and Trace Gas Emissions Indices Measured During the 2021 Boeing ecoDemonstrator Emissions Ground Test

We present particle and trace gas emissions indices sampled on the ground at 30 meters behind the CFM LEAP-1B engines of the Boeing ecoDemonstrator 737-9 aircraft. Testing was carried out at Boeing Field in Seattle, WA, USA in Fall of 2021. Four different fuels were investigated including a 100% sustainable aviation fuel (SAF), a petroleum-based Jet A fuel, and two SAF blends. Total and non-volatile particle number concentrations were measured with a pair of condensation particle counters with one operating behind a custom-built thermal denuder heated to 350 degrees Celsius. Similarly, total and non-volatile particle number size distributions were measured with a pair of Scanning Mobility Particle Sizers (SMPSs). Non-volatile particle mass was estimated from particle light absorption techniques using an assumed mass absorption coefficient, while particle chemical speciation was measured by an Soot Particle Aerosol Mass Spectrometer (SP-AMS). A detailed list of instruments is given on the project website [1]. Overall, the results are consistent with expectations based on ICAO Emissions Databank certification data for the LEAP-1B with a stark reduction in non-volatile particle number and mass observed for the higher thrust conditions when the combustor was staged. The production of volatile particles under these conditions as well as experimental considerations related to background subtraction methods will be discussed.

Benjamin A. Nault↗
NASA NTRS1977

Compact far ultraviolet emission source with rich spectral emission 1150-3100 A

The article describes a compact hollow Pt cathode emission source for the far UV, developed for use as a high-resolution wavelength standard in laboratory work or on spacecraft (specifically, the NASA International UV Explorer - IUE). The source is small, rugged, lightweight, spectrally rich, bright in the 1150-3200 A region, features long service life, low operating voltage, and lower power drain, and stably emits a large number of very sharp lines with a spectrum lending itself to projection onto the focal plane of a spectrograph. The source has successfully passed exacting environmental tests, and serves as a transfer standard for absolute sensitivity calibration of spectrometric instruments.

Mount, G. H.↗
NASA NTRS1985

Broad emission features in QSOs and active galactic nuclei. II - New observations and theory of Fe II and H I emission

Seven QSOs of low to intermediate redshift are characterized on the basis of: 320-850-nm spectra obtained with the UVITS spectrograph and image-dissector scanner at the f/9 Cassegrain focus of the 2.7-m reflecting telescope at McDonald Observatory; improved model calculations for the Fe II, Mg II, and Balmer lines and the Balmer continuum; and the theoretical results of Netzer and Wills (1983). The data are presented in tables, spectra, and difference spectra and described in detail. Fe II is found to be the largest contributor to the emission line spectrum, with strong UV Fe II lines in all QSOs (regardless of the strength of the optical Fe II lines) and an abundance ratio suggesting a factor-of-three overabundance of Fe relative to Mg and probably H. A discrepancy between the observed Fe II strength and the predictions of dustless standard photoionization models is noted, and the addition of a high-density component to the models is suggested.

Wills, B. J.↗
NASA NTRS1987

The IR emission features - Emission from PAH molecules and amorphous carbon particles

Given the current understanding of polycyclic aromatic hydrocarbons (PAHs), the spectroscopic data suggest that are at least two components which contribute to the interstellar emission spectrum: (1) free molecule-sized PAHs producing the narrow features and (2) amorphous carbon particles (which are primarily composed of an irregular 'lattice' of PAHs) contributing to the broad underlying components. An exact treatment of the IR fluorescence from highly vibrationally excited large molecules demonstrates that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. It is concluded that, since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is required along with an observational program focusing on the spatial characteristics of the spectra.

Allamandola, L. J.↗
NASA NTRS1990

Medium resolution studies of extreme ultraviolet emission from N2 by electron impact - The effect of predissociation on the emission cross section of the b 1Pi(u) state

The electron impact induced fluorescence spectrum of N2 is measured in the 102-134 nm range at a 0.05 nm spectral resolution. The spectral measurements provide the emission cross sections of the transitions of the b 1Pi(u)-X 1Sigma(+)g Birge-Hopfield I-band system. The structure and vibrational population distribution of this system are strongly affected by a configuration interaction of the valence b 1Pi(u) and Rydberg c 1Pi(u) and o 1Pi(u) states. The excitation function (0-400 eV) for the b-X (1,2) transition is measured and a modified Born approximation analytic model is applied to calculate the oscillator strength for the b 1Pi(u)-X band system. With the exception of the v-prime = 1 level, vibrational levels of the b 1Pi(u) state predissociate with a branching ratio of between 0.95 and 1.00. Predissociation of the b 1Pi(u) state contributes approximately six percent of the total dissociation cross section of N2 by electron impact at 100 eV.

James, Geoffrey K.↗
NASA NTRS1992

Three-dimensional structured shocks in AM Herculis-type systems. II - Cyclotron emission from ridge-shaped emission regions

The properties of cyclotron emission from accretion shocks in AM Herculis binaries are studied which result from nonuniform accretion onto linearly extended regions on the surface of the magnetic white dwarf. The resulting ridge-shaped postshock structures yield cyclotron spectra with prominent harmonic features over a wide range of viewing aspects, even for high total accretion rates, in contrast to what has been found previously for axisymmetric accretion shocks.

Wu, Kinwah↗
NASA NTRS1993

Observations of (S III) emission from Galactic radio sources - The detection of distant planetary nebulae and a search for supernova remnant emission

Narrow-band near-infrared imaging observations at wavelengths corresponding to forbidden S III 9069,9532 A have been carried out at the MDM 1.3 m telescope for 23 radio sources near the Galactic plane in an attempt to detect emission associated with nebulae marking the endpoints of stellar evolution. While none of the known remnants or remnant candidates were detected, 10 of the 11 PN candidates from a new radio imaging survey of the Galactic plane were clearly seen in the forbidden S III 9532 A line. We present a calculation of the relative efficacy of searching for PNe in the forbidden O III and forbidden S III lines; for the majority of all PNe, the observed forbidden S III 9532 A line is predicted to be stronger than forbiden O III 5007 A whenever the visual extinction exceeds 3 magnitudes. This makes forbidden S III the superior tracer of PNe at distances exceeding a few kpc. We briefly comment on the significance of this approach to defining the spatial distribution of the PN population of the Galaxy.

Kistiakowsky, V.↗
NASA NTRS1993

Infrared coronal emission lines and the possibility of their laser emission in Seyfert nuclei

Results are presented from detailed balance calculations, and a compilation of atomic data and other model calculations designed to support upcoming ISO and current observing programs involving IR coronal emission lines, together with a table with a complete line list of infrared transitions within the ground configurations 2s2 2p(k), 3s2 3p(k), and the first excited configurations 2s 2p and 3s 3p of highly ionized astrophysically abundant elements. The temperature and density parameter space for dominant cooling via IR coronal lines is presented, and the relationship of IR and optical coronal lines is discussed. It is found that, under physical conditions found in Seyfert nuclei, 14 of 70 transitions examined have significant population inversions in levels that give rise to IR coronal lines. Several IR coronal line transitions were found to have laser gain lengths that correspond to column densities of 10 exp 24-25/sq cm which are modeled to exist in Seyfert nuclei. Observations that can reveal inverted level populations and laser gain in IR coronal lines are suggested.

Greenhouse, Matthew A.↗
NASA NTRS1994

Correlation of far-infrared emission and radio continuum emission along the major axis of edge-on spiral galaxies

Using new High Resolution far-infrared (FIR) images we have determined FIR flux densities, the FIR luminosity, and intensity profiles along the major axis for eight nearby edge-on spiral galaxies. We present spatial comparisons between the FIR profiles in three of the four IRAS Bands (25, 60, 100 microns). We also present direct spatial comparisons between the 60 micron intensity profiles and intensity profiles from 20 cm radio continuum maps with identical resolution (approx. 60 sec) obtained from J. J. Condon. Using these profiles we have evaluated the 60 micron-to-20 cm ratio Q(sub 60) along the major axis for each galaxy and have compared the results to global Q(sub 60) values. This analysis reveals that a considerable amount of complicated structure exists within the disk of spiral galaxies. Closer examination of this disk structure will make it possible to place further constraints on the well known global far-infrared and radio continuum emission correlation.

Heikkila, Bryant↗