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  • Other Sources  (10)
  • 1975-1979  (10)
  • 1965-1969
  • 1
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    The recombination velocity at III-V compound heterojunctions with applications to Al (x) Ga(1-x)As-GaAs(1-y)Sb(y) (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Interface recombination velocity in AlxGa1-xAs-GaAs and A10.85 Ga0.15As-GaAs1-ySby heterojunction systems was studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAsSb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-157181 , SU-SEL-78-014 , TR-5127-1
    Format: application/pdf
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  • 2
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    Ion cyclotron resonance studies on the reaction of H2/+/ and D2/+/ ions with various simple molecules and hydrocarbons (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Journal of Chemical Physics; 62; Apr. 1
    Format: text
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  • 3
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    Proton transfer reactions from H3/+/ ions to N2, O2, and CO molecules (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The rate constants for proton transfer from H3(+) ions to N2, O2, and CO have been measured as function of hydrogen-buffer-gas partial pressure. The rate constant for proton transfer from H3(+) to N2 shows a very large pressure dependence, increasing from 1.0 by 10 to the -9th power cu cm/s at low H2 partial pressures to 1.7 by 10 to the -9th power cu cm/s at high H2 partial pressures. The rate constants for proton transfer from H3(+) to O2 and CO are constant with partial pressure of H2. The roles of excess vibrational energy in H3(+) ions and of equilibrium between forward and back reactions are discussed. Back reaction is observed only for the reaction of H3(+) ions with O2, and an equilibrium constant of 2.0 (plus or minus 0.4) at 298 K has been determined. From these data, the proton affinity of O2 is deduced to be 0.47 (plus or minus 0.11) kcal/mole higher than that of H2.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Chemical Physics Letters; 32; May 1
    Format: text
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  • 4
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    Unsteady flow in cavitating turbopumps (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Unsteady flow in a cavitating axial inducer pump is analyzed with the help of a simple two-dimensional cascade model. This problem was motivated by a desire to study the effect of unsteady cavitation on the so-called POGO instability in the operation of liquid rocket engines. Here, an important feature is a closed loop coupling between several different modes of oscillation, one of which is due to the basic unsteady characteristics of the cavitation itself. The approaching and leaving flow velocities up- and downstream of the inducer oscillate, and the cavity-blade system participates dynamically with the basic pulsating flow. In the present work, attention is focused on finding a transfer matrix that relates the set of upstream variables to those downstream. This quantity, which is essentially equivalent to cavitation compliance in the quasi-static analyses, is found to be complex and frequency dependent.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
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  • 5
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    Auger depth profiling of Au-Al/x/Ga/1-x/As interfaces and LPE Al/x/Ga/1-x/As-GaAs heterojunctions (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An attempt is made to report Auger depth profiles produced in a UHF ion-milling Auger system for intentionally 'graded' Al(x)Ga(1-x)As-GaAs heterojunctions, 'abrupt' growth heterojunctions of the same material, and Au-Al(x)Ga(1-x)As interfaces. It is found that the interface widths of the 'abrupt' growth heterojunctions did not fluctuate greatly from an average value of 110 A and that 'graded' growth samples had interface widths of about 525 to 1500 A. The results for the Au-containing samples indicate that an oxide layer was present between the Au and the Al(x)Ga(1-x)As.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Vacuum Science and Technology; 14; July-Aug
    Format: text
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  • 6
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    Auger profiling of 'abrupt' LPE Al/x/Ga/1-x/As-GaAs heterojunctions (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Auger analysis in conjunction with ion milling was used to study depth profiles of 'abrupt' Al/x/Ga/1-x/As-GaAs heterojunctions grown by liquid-phase epitaxial (LPE) techniques. Results are presented on samples with x = 0.43, 0.60, and 0.85. The interface widths obtained are listed in a table together with the growth conditions and the layer thicknesses. The values for the layer thicknesses are in the range from 125 to 950 A. It is found that for thin layers the interface widths do not differ greatly from the average value of 110A.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics; 48; July 197
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  • 7
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    Investigation of a reattaching turbulent shear layer Flow over a backward-facing step (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper studies incompressible flow over a backward-facing step in order to investigate the flow characteristics in the separated shear layer, the reattachment zone, and the redeveloping boundary layer after reattachment. It is shown that turbulent intensities and shear stress reach maxima in the reattachment zone, followed by rapid decay near the surface after reattachment. In addition, it is found that downstream of reattachment, the flow returns very slowly to the structure of an ordinary turbulent boundary layer.
    Keywords: AERODYNAMICS
    Type: Flow in primary, non-rotating passages in turbomachines; Dec 02, 1979 - Dec 07, 1979; New York, NY
    Format: text
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  • 8
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    Lean, premixed, prevaporized fuel combustor conceptual design study (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Four combustor concepts, designed for the energy efficient engine, utilize variable geometry or other flow modulation techniques to control the equivalence ratio of the initial burning zone. Lean conditions are maintained at high power to control oxides of nitrogen while near stoichometric conditions are maintained at low power for low CO and THC emissions. Each concept was analyzed and ranked for its potential in meeting the goals of the program. Although the primary goal of the program is a low level of nitric oxide emissions at stratospheric cruise conditions, both the ground level EPA emission standards and combustor performance and operational requirements typical of advanced subsonic aircraft engines are retained as goals as well. Based on the analytical projections made, two of the concepts offer the potential of achieving the emission goals; however, the projected operational characteristics and reliability of any concept to perform satisfactorily over an entire aircraft flight envelope would require extensive experimental substantiation before engine adaptation can be considered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159647 , PWA-5626-12
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  • 9
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    Comments on 'Reactions of excited and ground state H3/+/ ions with simple hydrides and hydrocarbons' (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: International Journal of Mass Spectrometry and Ion Physics; 18; 1975
    Format: text
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  • 10
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    Large eddy simulation of turbulent channel flow: ILLIAC 4 calculation (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The three-dimensional time dependent equations of motion were numerically integrated for fully-developed turbulent channel flow. A large scale flow field was obtained directly from the solution of these equations, and small scale field motions were simulated through an eddy viscosity model. The calculations were carried out on the ILLIAC 4 computer. The computed flow patterns show that the wall layer consists of coherent structures of low speed and high speed streaks alternating in the spanwise direction. These structures were absent in the regions away from the wall. Hot spots, small localized regions of very large turbulent shear stress, were frequently observed. The profiles of the pressure velocity-gradient correlations show a significant transfer of energy from the normal to the spanwise component of turbulent kinetic energy in the immediate neighborhood of the wall ('the splatting effect').
    Keywords: AERONAUTICS (GENERAL)
    Type: NASA-TM-78619 , A-7952 , AGARD Symp. on Turbulent Boundary Layer, Experiment, Theory, and Modelling; Sep 24, 1979 - Sep 27, 1979; The Hague; Netherlands
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