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  • 1
    Publication Date: 2019-07-13
    Description: A series of experiments have been conducted at Langley Research Center to determine the feasibility of using electron-beam fluorescence to measure the free-stream static density of gaseous helium flow over a wide range of conditions. These experiments were conducted in the Langley hypersonic helium tunnel facility and its 3-inch prototype. Measurements were made for a range of stagnation pressures and temperatures and produced free-stream number densities of 1.53 x 10 to the 23rd to 1.25 x 10 to the 24th molecules/cu m and static temperatures from 2 K to 80 K. The results showed the collision quenching cross section to be 4.4 x 10 to the -15th sq cm at 1 K and to have a weak temperature dependence of T to the 1/6. With knowledge of these two values, the free-stream number density can be measured quite accurately.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 79-1085 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Jun 04, 1979 - Jun 06, 1979; Orlando, FL
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  • 2
    Publication Date: 2019-06-27
    Description: The response of a tungsten-scintillator ionization spectrometer to accelerated particle beams has been investigated. Results obtained from exposure of the approx. 1000 g/sq cm apparatus to 5, 10, and 15 GeV/c electrons and pions as well as to 2.1 GeV/nucleon C-12 and O-16 ions are presented. These results include cascade-development curves, fractions of the primary energy measured by the spectrometer, and resolutions of the apparatus for measuring the primary energies. For 15 GeV/c electrons, an average of about 82% of the incident energy is measured by the apparatus with resolution (normal standard deviation) of about 6%. For 15 GeV/c pions, an average of about 65% of the incident energy is measured with resolution of about 18%. The energy resolution improves with increasing energy and with increasing depth of the spectrometer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 126; 1975
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  • 3
    Publication Date: 2019-06-27
    Description: A system for remotely measuring velocities present in discrete volumes of air is described. A CO2 laser beam is focused by a telescope at such a volume, a focal volume, and within the focusable range, near field, of the telescope. The back scatter, or reflected light, principally from the focal volume, passes back through the telescope and is frequency compared with the original frequency of the laser, and the difference frequency or frequencies represent particle velocities in that focal volume.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 4
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    Publication Date: 2019-07-13
    Description: A brief overview is provided of the coherent Doppler lidar work at the Marshall Space Flight Center, taking into account the status and planned development of the system to be used for severe storms research. The considered system is a CW Doppler lidar operating at a wavelength of 10.6 micrometers. This lidar uses a 20 watt carbon dioxide laser. It has a range which is continuously variable from 60 m to approximately 600 m. Range variation is achieved through changing the focus of a 30 cm f/2 Cassegrainian telescope. Successful measurements with the CW lidar have included two and three dimensional wind profiles, wing tip vortex tracks and profiles, dust devil tracks and profiles, and transverse as well as line-of-sight wind velocities. The pulsed lidar in recent ground tests has succeeded in measuring clear air returns to a range of 13 km and has provided substantial information on velocities associated with the gust fronts of thunderstorms.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Conference on Atmospheric Environment of Aerospace Systems and Applied Meteorology; Nov 14, 1978 - Nov 16, 1978; New York, NY
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  • 5
    Publication Date: 2006-01-16
    Description: The Deep Space Network is in the process of fielding high-density digital instrumentation recorders for support of the Pioneer Venus 1978 entry experiment and other related tasks. It has long been obvious that these recorders would also serve well as the recording medium for very long base interferometry (VLBI) experiments with relatively weak radio sources, provided that a suitable correlation processor for these tape recordings could be established. The overall design and current status of a VLBI correlator designed to mate with these tape recorders are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 90-98
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  • 6
    Publication Date: 2011-08-17
    Description: Two CCD techniques were discussed for performing an N-point sampled data correlation between an input signal and an electronically programmable reference function. The design and experimental performance of an implementation of the direct time correlator utilizing two analog CCDs and MOS multipliers on a single IC were evaluated. The performance of a CCD implementation of the chirp z transform was described, and the design of a new CCD integrated circuit for performing correlation by multiplication in the frequency domain was presented. This chip provides a discrete Fourier transform (DFT) or inverse DFT, multipliers, and complete support circuitry for the CCD CZT. The two correlation techniques are compared.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; 6 p
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  • 7
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    Publication Date: 2011-08-17
    Description: A variety of programs have been conducted within EPA to evaluate the capability of various ground-based remote-sensing techniques for measuring the SO2 concentration, velocity, and opacity of effluents from coal-burning power plants. The results of the remote measurements were compared with the results of instack measurements made using EPA reference methods. Attention is given to infrared gas-filter correlation radiometry for SO2 concentration, Fourier-transform infrared spectroscopy for SO2 concentration, ultraviolet matched-filter correlation spectroscopy for SO2 concentration, infrared and ultraviolet television for velocity and SO2 concentration, infrared laser-Doppler velocimetry for plume velocity, and visible laser radar for plume opacity.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Environmental Science and Technology; 11; Oct. 197
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  • 8
    Publication Date: 2011-08-16
    Description: An efficient scanning method for read-out of a multiwire proportional counter hodoscope is presented. This method which utilizes the grouping of wires in the hodoscope read-out system offers distinct advantages in speed and simplicity over systems employing long shift registers. Power consumption and cost can be minimized with this method because of slower clock speeds and a low parts count. This system has been constructed and used on a hodoscope for cosmic-ray trajectory measurements and a lower-power version has been designed for satellite applications.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 117; 1975
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  • 9
    Publication Date: 2019-06-27
    Description: The pressure modulator technique was evaluated for monitoring pollutant gases in the Earth's atmosphere of altitude levels corresponding to the mid and lower troposphere. Using an experimental set up and a 110 cm sample cell, pressure modulator output signals resulting from a range of gas concentrations in the sample cell were examined. Then a 20 cm sample cell was modified so that trace gas properties in the atmosphere could be simulated in the laboratory. These gas properties were measured using an infrared sensor.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-159175
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  • 10
    Publication Date: 2019-06-27
    Description: Electromagnetic cascades in a lead-emulsion chamber have been studied to determine the effect of air gaps on the upstream sides of the emulsions. Such air gaps cause a change in the form of the radial distribution of electron tracks, making cascades appear older and giving incorrect energy estimates. The number of tracks remaining within a radius r was found to vary as exp(-g/G), where g is the gap thickness. The characteristic gap thickness in mm is G = 3.04 + 1.30 ln (Err per GeV per sq mm) where E is the energy of the initiating gamma ray. Use of this relation provides a significant correction to cascade-energy estimates and allows one to calculate the effect of different gap thicknesses on the energy threshold for visual detection of cascades.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 126; 1975
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