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  • 1
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    Properties of the Io plasma torus inferred from Voyager EUV data (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A physical model for the Io plasma torus is constructed to explain the EUV radiative emission observed by the Voyager UV spectrometer. Electron impact excitation rate coefficients for electronic transitions of S III, S IV, O II and O III are calculated by the method of distorted waves (Davis, Kepple, and Blaha, 1976); these coefficients account for the asymmetric shape of the 686 A feature. It is concluded that the electron gas must have a distribution function with a non-Maxwellian tail. An approximate representation of the distribution function as two temperature components requires a cold component of 3.5-4 eV and density of 2000 per cu cm and a hot component of about 100 eV and density of 50-100 per cu cm to satisfy observational constraints.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astrophysical Journal; vol. 238
    Format: text
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  • 2
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    Level shifts and inelastic electron scattering in dense plasmas (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A completely quantum mechanical formalism has been developed to describe the high density plasma effects on fundamental atomic parameters. Both the bound and free electrons are treated by a method which in principle is similar to Hartree's self-consistent field method. The free plasma electrons' wavefunction is obtained from the Schroedinger equation with the effective potential representing the spherically averaged Coulomb interaction with bound and free electrons. Results are given for level shifts, coefficients of transition probabilities, and electron collision cross sections of Ne(9+) for temperatures of 200 and 500 eV for an electron density range of 1-6 x 10 to the 24th per cu cm.
    Keywords: PLASMA PHYSICS
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  • 3
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    The properties of polycrystalline silicon solar cells with controlled titanium additions (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: By coupling the results of electrical measurements, such as spectral response, lighted and dark I-V determinations, and deep-level-transient spectroscopy with optical and laser scan photomicroscopy, the effects of grain boundaries and impurities on silicon solar cells were evaluated. Titanium, which produces two deep levels in silicon, degrades cell performance by reducing bulk lifetime and thus cell short-circuit current. Electrically active grain boundaries induce carrier recombination in the bulk and depletion regions of the solar cell. Experimental data imply a small but measurable segregation of titanium into some grain boundaries of the polycrystalline silicon containing high Ti concentration. However, for the titanium-contaminated polycrystalline material used in this study, solar cell performance is dominated by the electrically active titanium concentration in the grains. Microstructural impacts on the devices are of secondary importance
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-28; Jan. 198
    Format: text
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  • 4
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    Ion plating studies for high temperature applications (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An experimental project was undertaken to ion plate, by electron beam evaporation, Al films onto 4340 steel substrates using (and at the time troubleshooting) the custom built V.T.A. 7375 electron beam ion plating system. A careful recent literature and commercial vendor survey indicates possible means of improving the trouble plagued V.T.A. system.
    Keywords: METALLIC MATERIALS
    Type: Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 17 p
    Format: text
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  • 5
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    Dielectronic recombination rates, ionization equilibrium, and radiative emission rates for calcium and nickel ions in low-density high-temperature plasmas (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The total dielectronic recombination rates for Ca and Ni ions were calculated taking into account autoionization to excited states of the recombining ion and stabilizing radiative transitions of the recombining electron. Radiative transitions of the recombining ion are found to be the dominant stabilizing processes, and the relative importance of Delta n = 0 and Delta n not equal to 0 transitions in the relevant temperature region is determined for each ion. The relative importance of the Delta n = 0 and Delta n not equal to 0 contributions is significantly altered for some ions by the inclusion of autoionization to excited levels. The relative abundance of the various ionization stages has been determined by using a corona equilibrium model in which collisional ionization and inner-shell excitation followed by autoionization are balanced by direct radiative and dielectronic recombination.
    Keywords: PLASMA PHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
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  • 6
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    Absolute brightness temperature measurements at 3.5-mm wavelength (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Careful observations have been made at 86.1 GHz to derive the absolute brightness temperatures of the sun (7914 + or - 192 K), Venus (357.5 + or - 13.1 K), Jupiter (179.4 + or - 4.7 K), and Saturn (153.4 + or - 4.8 K) with a standard error of about three percent. This is a significant improvement in accuracy over previous results at millimeter wavelengths. A stable transmitter and novel superheterodyne receiver were constructed and used to determine the effective collecting area of the Millimeter Wave Observatory (MWO) 4.9-m antenna relative to a previously calibrated standard gain horn. The thermal scale was set by calibrating the radiometer with carefully constructed and tested hot and cold loads. The brightness temperatures may be used to establish an absolute calibration scale and to determine the antenna aperture and beam efficiencies of other radio telescopes at 3.5-mm wavelength.
    Keywords: ASTRONOMY
    Type: IEEE Transactions on Antennas and Propagation; AP-28; May 1980
    Format: text
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  • 7
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    Impurities in silicon solar cells (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper investigates the effects of metallic impurities on the performance of silicon solar cells. Czochralski and polycrystalline ingots were employed with boron and phosphorus as primary dopants and with controlled additions of secondary impurities. The data obtained from over 200 crystals indicate that impurity-induced performance loss is primarily due to a reduction of the base diffusion length. Based on this observation, a model is developed which predicts cell performance as a function of secondary impurity concentrations. The model calculations are in good agreement with experimental values except for Cu, Ni, Fe, and to a lesser degree, carbon, which at higher concentrations degrade the cell by junction defect mechanisms.
    Keywords: SOLID-STATE PHYSICS
    Type: IEEE Transactions on Electron Devices; ED-27; Apr. 198
    Format: text
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  • 8
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    Design and verification of a cloud field optical simulator (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A concept and an apparatus designed to investigate the reflected and transmitted distributions of light from optically thick clouds is presented. The Cloud Field Optical Simulator (CFOS) is a laboratory device which utilizes an array of incandescent lamps as a source, simulated clouds made from cotton or styrofoam as targets, and an array of silicon photodiodes as detectors. The device allows virtually any source-target-detector geometry to be examined. Similitude between real clouds and their CFOS cotton or styrofoam counterparts is established by relying on a linear relationship between optical depth and the ratio of reflected to transmitted light for a semi-infinite layer. Comparisons of principal plane radiances observed by the CFOS with Monte Carlo computations for a water cloud at 0.7 microns show excellent agreement.
    Keywords: OPTICS
    Type: A Lab. Invest. of the Reflective Properties of Simulated, Opt. Thick Clouds; 37 p
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  • 9
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    Composites for large transports - Facing the challenge (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: NASA has undertaken development and test programs in collaboration with the large transport aircraft construction industry, in order to remove existing barriers to the use of composite material primary structures and to assess their advantages in terms of both acquisition cost and mission performance. These programs are expected to reach design technology readiness for wing and fuselage structures by 1988, paving the way for the validation of design and manufacturing methods in the early 1990s. While composites promise a reduction in fuselage manufacturing costs, it is judged that the relative cost of a metallic wing will be more difficult to surpass. Nevertheless, a 40 percent wing weight saving may more than compensate for increased wing structure cost.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Aerospace America (ISSN 0740-722X); 22; 58-62
    Format: text
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  • 10
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    Spacescapes/Payloads for the Arts: Administrative and Technical Aspects of the New Wave Ruby Falls Get Away Special Project are Reviewed in Perspective (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The production of artificial auroras for use in environmental art is discussed. The involvement of NASA and the space shuttle program in projects or the arts is reviewed.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA. Goddard Space Flight Center Get Away Spec. Expt. Symp.; p 25-32
    Format: application/pdf
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