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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 577 records · Page 32
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NASA NTRS1982

EUV spectroscopic plasma diagnostics for the solar wind acceleration region

Possibilities are considered for probing physical conditions in the solar corona with strong EUV resonance lines from ions such as N V, O VI, Ne VIII, Mg X, and Si XII. Through measurements of the intensities and profiles of EUV spectral lines with coronagraphic instrumentation employing normal incidence reflecting optics, it is possible to acquire information on electron, proton, and ion temperatures and velocity distributions; electron, H I, and ion densities; mass flow and nonthermal velocities; and chemical abundances. This information will provide critical empirical constraints on physical processes responsible for plasma heating, solar wind acceleration, and transport of mass, momentum, and energy in the solar corona, as well as providing constraints on theoretical models for solar and stellar coronae and mass loss.

Kohl, J. L.↗
NASA NTRS1982

Spectroscopic line parameters of NH3 and PH3 in the far infrared

NH3 and PH3 rotation and rotation-inversion line parameters in the far to medium IR are calculated for remote sounding purposes of planetary atmospheres; 1607 lines of (N-14)H3, 362 lines of (N-15)H3 and 325 lines of PH3 are compiled. The absolute intensity formulation has been reviewed in the case of rotation and rotation-inversion lines of molecules with C(3v) symmetry. The justification for the general agreement between the authors, and comparisons with other published expressions are given.

Husson, N.↗
NASA NTRS1981

Spectroscopic remote sensing for geological applications

Remote sensing is being used with increasing frequency in the development of geologic maps and in the exploration process. Spectral data from airborne and spaceborne multispectral scanners provide information on rock type and vegetation stress, important in geologic applications. Emphasis is now being placed on direct identification of materials rather than discrimination among geologic units. To do this, higher spectral resolution systems with wider spectral coverage than currently available are required. Imaging spectroscopy in the 0.4 - 14 microns region appears to be the answer.

Goetz, A. F. H.↗
NASA NTRS1982

Preliminary submillimeter spectroscopic measurements using a submillimeter heterodyne radiometer

A submillimeter heterodyne radiometer uses a submillimeter laser, pumped by a CO2 laser, as a local oscillator and a room temperature Schottky barrier diode as the first IF mixer. The radiometer can resolve spectral lines in the submillimeter region of the spectrum (arising from pure rotational molecular transitions) to within 0.3 MHz, using acousto-optic spectrum analyzer which measures the power spectrum by simultaneously sampling 0.3 MHz wide channels over a 100 MHz bandwidth spanning the line. Preliminary observations of eight spectral lines of H2O2, CO, NH3 and H2O, all lying in the 434-524 micrometer wavelength range are described. All eight lines were observed using two local oscillator frequencies obtained by operating the submillimeter laser with either methyl fluoride (CH3F) or formic acid (HCOOH) as the lasing gas. Sample calculations of line parameters from the observed data show good agreement with established values. One development goal is the size and weight reduction of the package to make it suitable for balloon or shuttle experiments to detect trace gases in the upper atmosphere.

Safren, H. G.↗
NASA NTRS1982

Spectroscopic imaging of the thermosphere from the Space Shuttle

The design features, performance characteristics, and intended missions for the Imaging Spectrometric Observatory scheduled to fly on the first Spacelab Shuttle mission in 1983 are described. The instrument comprises an array of five imaging spectrometers covering the spectral range 300-1200 A. The spectrometers operate simultaneously, using CCDs as collector elements. Resolution on the first flight will be limited to 3 A, with coverage to containing the dynamic range from nocturnal signals to the bright earth. A minicomputer in the Spacelab will permit crewmember interaction with the measurements, while data will be telemetered in real-time to a ground station. Initial mission objectives include observations of dayglow, nightglow, and twilightglow over the full wavelength range capability.

Torr, M. R.↗
NASA NTRS1982

Laboratory studies of photochemical and spectroscopic phenomena related to comets

The relationship between laboratory observations and cometary phenomena is reviewed, with particular attention to how laboratory studies must be done to obtain all data needed for astronomical purposes. It is pointed out how supersonic expansion of the gas evaporating from the nucleus can affect the photochemical lifetime and the energy partitioning among the fragments. The use of the CS radical as a remote sensing probe of conditions in the inner coma is also discussed.

Jackson, W. M.↗
NASA NTRS1982

Probing the solar wind acceleration region using spectroscopic techniques

Recent developments in the use of UV and EUV coronagraphic spectroscopy for studying the physical conditions in the solar corona in the solar wind acceleration region from a heliocentric distance of 1.8 solar radii out to 8 solar radii and beyond are reviewed. Particular attention is given to theoretical considerations and techniques for the estimation of particle ionization balances and velocity distributions, coronal temperatures, neutral hydrogen, proton, electron and ion temperatures and densities, outflow velocities, charge states and chemical abundances from spectral line radiation and white-light measurements. Observational considerations are discussed as they relate to requirements for stray light rejection and the effects of geocorona and interplanetary dust emission in coronagraph design. Results of coronal H I Lyman alpha and white light observations made during sounding rocket flights are summarized, and future observational programs making use of rocket-borne instruments, Detached Shuttle Payload Flights, Spacelab or space platforms are indicated.

Withbroe, G. L.↗
NASA NTRS1982

Ground-based infrared spectroscopic measurements of atmospheric hydrogen cyanide

A number of lines of the nu-3 band of hydrogen cyanide have been detected in solar absorption spectra recorded near sunrise and sunset at Kitt Peak National Observatory (elevation 2095 m) with a 0.01/cm resolution Fourier transform spectrometer. Analysis of two of the strongest and best isolated lines has led to a value of 2.73 x 10 to the 15th molecules/sq cm for the vertical column abundance of HCN above Kitt Peak. The accuracy of this value is estimated as + or - 25%. This result, combined with the stratospheric concentration of HCN derived by Coffey, Mankin, and Cicerone (1981), yields 166 parts per trillion by volume for the average mixing ratio of HCN between 2 and 12 km. This is the first determination of the HCN concentration in the nonurban troposphere.

Rinsland, C. P.↗
NASA NTRS1983

HR 7578 - A K dwarf double-lined spectroscopic binary with peculiar abundances

The number of double-lined K and M dwarf binaries which is currently known is quite small, only a dozen or less of each type. The HR 7578 system was classified as dK5 on the Mount Wilson system and as K2 V on the MK ystem. A summary of radial-velocity measurements including the observatory and weight of each observation is given in a table. The star with the stronger lines has been called component A. The final orbital element solution with all observations appropriately weighted was computed with a differential corrections computer program described by Barker et al. (1967). The program had been modified for the double-lined case. Of particular interest are the very large eccentricity of the system and the large minimum masses for each component. These large minimum masses suggest that eclipses may be detectable despite the relatively long period and small radii of the stars.

Fekel, F. C., Jr.↗
NASA NTRS1983

Coherent anti-Stokes Raman spectroscopic modeling for combustion diagnostics

The status of modelling the coherent anti-Stokes Raman spectroscopy (CARS) spectra of molecules important in combustion, such as N2, H2O, and CO2, is reviewed. It is shown that accurate modelling generally requires highly precise knowledge of line positions and reasonable estimates of Raman linewidths, and the sources of these data are discussed. CARS technique and theory is reviewed, and the status of modelling the phenomenon of collisional narrowing at pressures well above atmospheric for N2, H2O, and CO2 is described. It is shown that good agreement with experiment can be achieved using either the Gordon rotational diffusion model or phenomenological models for inelastic energy transfer rates.

Hall, R. J.↗
NASA NTRS1984

Least squares methods of analyzing spectroscopic data

The development of efficient techniques for extracting the maximum amount of information from the spectra of atmospheric molecules with a minimum of observer bias is discussed. In particular, an overview of the methods of line by line and whole band analysis is presented.

Shaw, J. H.↗
NASA NTRS1984

Determination of the succinonitrile-benzene and succinonitrile-cyclohexanol phase diagrams by thermal and UV spectroscopic analysis

Equilibrium temperature-composition diagrams were determined for the two organic systems, succinonitrile-benzene and succinonitrile-cyclohexanol. Measurements were made using the common thermal analysis methods and UV spectrophotometry. Succinonitrile-benzene monotectic was chosen for its low affinity for water and because UV analysis would be simplified. Succinonitrile-cyclohexanol was chosen because both components are transparent models for metallic solidification, as opposed to the other known succinonitrile-based monotectics.

Kaukler, W. F.↗
NASA NTRS1983

Monodeuterated methane in the outer solar system. I Spectroscopic analysis of the bands at 1.55 and 1.95 microns

The analysis of the near-infrared spectrum of monodeuterated methane (CH3D) near 6400/cm and 5100/cm is presented. Three new parallel bands which have locally perturbed upper states connecting with the ground state are identified, and approximate rotational constants are derived. The band centered near 6425/cm and the 9613 A band previously analyzed by Lutz, Danehy, and Ramsay (1978) are found to form an apparent vibrational progression with the nu2 fundamental at 2200/cm, and vibrational assignments of 3nu2 and 5nu2, respectively, are proposed. Detailed comparison of the rotational constants of the states involved is shown to support these assignments.

Lutz, B. L.↗
NASA NTRS1983

Ultraviolet spectroscopic observations of some Be stars of later type and A-F type shell stars

High-dispersion IUE spectra of 18 later type Be and A-F type shell stars as well as eight standard nonemission line stars have been analyzed for anomalous ionization and mass loss effects. It is found that superionization in the Be stars extends to the latest spectral subtypes but does not seem to be present in the A-F type stars. The superionized lines in the Be stars appear to be correlated with v sin i. Asymmetrical or violet-displaced resonance lines suggesting mass loss are observed in all the Be stars except one, in some of the standard stars, but not in the A-F stars. Lower limits to the mass loss rates computed from Si IV lines range between 5.3 x 10 to the -12th and 3.5 x 10 to the -11th solar masses/yr, with Be shell stars showing the largest values. Mass loss is correlated with luminosity and effective temperature but not with rotation.

Carpenter, K. G.↗