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  • Other Sources  (3)
  • 1985-1989  (1)
  • 1970-1974  (2)
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  • 1
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    Methods for utilizing maximum power from a solar array (1972)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: A preliminary study of maximum power utilization methods was performed for an outer planet spacecraft using an ion thruster propulsion system and a solar array as the primary energy source. The problems which arise from operating the array at or near the maximum power point of its 1-V characteristic are discussed. Two closed loop system configurations which use extremum regulators to track the array's maximum power point are presented. Three open loop systems are presented that either: (1) measure the maximum power of each array section and compute the total array power, (2) utilize a reference array to predict the characteristics of the solar array, or (3) utilize impedance measurements to predict the maximum power utilization. The advantages and disadvantages of each system are discussed and recommendations for further development are made.
    Keywords: AUXILIARY SYSTEMS
    Type: JPL Quarterly Tech. Rev., Vol. 2, No. 1; p 37-48
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Energetic (above 60 eV) atmospheric photoelectrons (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Data from low altitude plasma instrument (LAPI) on Dynamics Explorer 2 document a population of high-energy (up to 800 eV) atmospheric photoelectrons that has not been reported in the published literature. The source of these photoelectrons is postulated to be the soft X-ray portion of the whole sun spectrum. This conclusion is supported by sunrise-sunset characteristics that track those of the classical (below 60 eV) EUV-produced photoelectrons, and theoretical results from two models that incorporate the soft X-ray portion of the solar spectrum. The models include K-shell ionization effects and predict peaks in the photoelectron spectrum due to Auger electrons emitted from oxygen and nitrogen. The peak for nitrogen is observed as predicted, but the peak for oxygen is barely observable. Excellent quantitative agreement is achieved between theory and experiment by using reasonable adjustments to the few published soft X-ray spectra based on solar activity. The upflowing energetic photoelectrons provide a heretofore unknown source of electrons to the magnetosphere. They occur whenever and wherever the sun is up, that is, at all invariant latitudes. Their density is low, but they are steady and ubiquitous. If scattering and trapping occur on closed field lines, then photoelectrons could contribute as a significant particle source and thus represent a new facet of magnetosphere-ionosphere coupling.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 15335-15
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    AC impedance of silicon solar cells. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The equivalent source impedance of a solar array is an important parameter in the design and analysis of solar array power conditioning equipment. Laboratory impedance tests have been performed on individual silicon solar cells and the test results have been correlated with P-N junction theory as developed by Shockley. The impedance has been broken into resistive and reactive components. The impedance has been expressed as a function of DC operating point and frequency. A practical application of the individual cell characteristics is presented in a solar array simulator design.
    Keywords: AUXILIARY SYSTEMS
    Type: Intersociety Energy Conversion Engineering Conference; Energy 70; Sep 21, 1970 - Sep 25, 1970; Las Vegas, NV
    Format: text
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    NASA TECHNICAL REPORTS
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