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  • Other Sources  (752)
  • SOLAR PHYSICS  (279)
  • INSTRUMENTATION AND PHOTOGRAPHY  (248)
  • FLUID MECHANICS AND HEAT TRANSFER  (225)
  • 1985-1989
  • 1980-1984  (752)
  • 1981  (752)
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  • Other Sources  (752)
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Years
  • 1985-1989
  • 1980-1984  (752)
Year
  • 1
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    Effect of shear stress on cell cultures and other reactor problems (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Anchorage dependent cell cultures in fluidized beds are tested. Feasibility calculations indicate the allowed parameters and estimate the shear stresses therein. In addition, the diffusion equation with first order reaction is solved for the spherical shell (double bubble) reactor with various constraints.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 19 p
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  • 2
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    Measurement of the solar constant (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The absolute value of the solar constant and the long term variations that exist in the absolute value of the solar constant were measured. The solar constant is the total irradiance of the Sun at a distance of one astronomical unit. An absolute radiometer removed from the effects of the atmosphere with its calibration tested in situ was used to measure the solar constant. The importance of an accurate knowledge of the solar constant is emphasized.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 3
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    Solar spectrum from 170 to 3200 nanometers (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The spectral irradiance of the Sun between 170 and 3200 nanometers was measured to determine accurately the solar constant, its possible variation with the solar cycle, and the wavelength range responsible for the observed variations. It is pointed out that measurements over very long time periods (10 years) involving flights of the same instrument on future Spacelab missions will be required. Few spectral solar irradiation measurements ranging from the near ultraviolet to the near infrared have been performed yet. The most extensive solar irradiation measurements were obtained by a spectrometer onboard an aircraft or from high altitude observatories. The full disk irradiation flux was measured, corrections for atmospheric absorption are applied in all of the measurements.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 4
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    Active cavity radiometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The active cavity radiometer (ACR) experiment on the Spacelab 1 mission to measure the total solar irradiance is discussed. Short and long term variations in the total solar output of optical energy are studied. Solar total irradiance observation provides information on the solar cycle and other long term trends in solar output that are of climatological significance as well as short term solar physics phenomena. The interaction of solar radiation with the Earth's atmosphere, oceans, and land masses provides the primary driving forces for the formation of weather systems and the determination of climate. Astrophysical measurements determine the total energy flux. The principal role of the ACR observations support extended solar irradiance experiments on free flying satellites. Solar irradiance measurements are important in the establishment of the radiation scale at the solar total flux level in the international system of units (SI).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 5
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    Very wide field camera (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The study of galactic and faint extragalactic extended sources and peculiar ultraviolet objects by a very wide field of view camera, operated in the ultraviolet photometric and spectrometric modes is discussed. The photometric mode is direct photography through filters for observation of the following sources: (1) large scale distribution of ultraviolet radiation in the Milky Way; (2) diffusion of the galactic light above the galactic plane and in front of the large absorbing clouds; (3) the optical emission of the interstellar matter; (4) stars, and starlike objects with diameters less than 3 arc minutes. In the spectrometric mode (nebular spectrograph) the light from the center of the photometric field is concentrated on a slit covering 10 degrees by 10 arc minutes on the sky.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 6
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    Personal miniature electrophysiological tape recorder (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-05
    Description: The use of a personal miniature electrophysiological tape recorder to measure the physiological reactions of space flight personnel to space flight stress and weightlessness is described. The Oxford Instruments Medilog recorder, a battery-powered, four-channel cassette tape recorder with 24 hour endurance is carried on the person and will record EKG, EOG, EEG, and timing and event markers. The data will give information about heart rate and morphology changes, and document adaptation to zero gravity on the part of subjects who, unlike highly trained astronauts, are more representative of the normal population than were the subjects of previous space flight studies.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 2 p
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  • 7
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    Metric camera experiment (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: A test of the mapping capabilities of high resolution space photography taken at the resolution limit of image motion on large film format is planned. The metric camera system and its planned operation are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 8
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    Waves in the OH emissive layer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: Photography and measurement of cloud-like structures of bright parallel bands observed in near infrared photography of the night sky is planned. The instrument is described and the purpose of the experiment summarized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 2 p
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  • 9
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    Grille spectrometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: High resolution infrared spectroscopic observations of the Earth's limb in the wavelength range characteristic of the vibrational-rotational lines of trace atmospheric constituents is planned. The instrument and its operation and the purpose of the experiments are summarized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 10
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    Capillary priming characteristics of a dual passage heat pipe in zero-g (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Technical improvements of a long life heat rejection system, suitable for long duration high power missions, that can be constructed and deployed in orbit is discussed. A mathematical model is formulated and a computer program developed which describes the transient priming characteristics of a dual passage heat pipe. An experimental test package is described for flight in the KC-135 Zero-g Aircraft, to be used to verify the modeling predictions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 50 p
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  • 11
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    An automatic light scattering CCN counter (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The counter is a static thermal diffusion chamber which has been modified to include an optical system for the determination of droplet concentration by the measurement of scattered light. The determination of concentration is made by measurement of the peak scattered light signal from the cloud of growing droplets which is a function of both the droplet concentration and chamber supersaturation. Because the formation of the peak is related to the rate of growth of the droplets and sedimentation, both of which are determined by supersaturation, the system calibration can be uniquely determined by comparison with an absolute counter such as a static diffusion chamber with a photographic recording system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 40-41
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  • 12
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    Cloud condensation nucleus counter by impactor sampling technique (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Unlike typical CCN counters, this device counts the numbers of water droplets condensed on aerosol particles sampled on a microcover glass at various different relative humidities. The relative humidities ranged from 75 percent to a calculated value of 110 percent. A schematic of the apparatus is shown. The individual CCN can be identified in an optical micrograph and scanning electron micrograph and may be inspected for their chemical composition later.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 35-36
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  • 13
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    The CCN counter of the IOPG of Puy de Dome: Main characterisics and results of measurements (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In performing the data analysis of the measurements achieved during the Workshop with the device, a global approach was preferred rather than an individual analysis, in order to illustrate some main characteristics in the behavior of the device with respect to a mean behavior resulting from a general survey of all the equipments involved in each experiment. The device tends generally to overestimate the CCN concentrations measured near the high supersaturations and sometimes underestimates the concentrations close to 0.1% or 0.2% of supersaturation. Despite the fact that it belongs to a type of static diffusion chamber, it shows, however, similar spectra to those obtained with other types of chambers (continuous flow diffusion chamber and haze chamber).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 17-19
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  • 14
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    Contribution to CCN Workshop report from University of Wyoming group (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The group's CCN counter is described. It is a static, horizontal, parallel plate thermal gradient diffusion chamber. Examples of the application of the CCN are presented and include the CCN spectra measured during the winter of 1978-79 near Elk Mountain, Wyoming. Comparisons of droplet concentrations derived from upwind CCN spectra are covered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 11-13
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  • 15
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    Measurement of the aerosol size distribution with NRL's mobility analyzer (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The size distribution was measured in the size range between 0.0057 and 0.57 micrometer radius. A description of the instrumentation and data analysis is given, together with the measured size distributions calculated for 23 experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 69-78
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  • 16
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    Modified MEE Industries static thermal gradient diffusion cloud chamber (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The experiments performed at the Workshop were undertaken to confirm the calculated sample volume, determine the usable range of supersaturation, and minimum detectable size. Comparison of absolute CCN concentrations with other state-of-the-art continuous flow diffusion chambers at supersaturations near 1 percent indicated that the volume used produced CCN concentrations well within the range of CCN concentrations determined at the workshop. This agreement is interpreted to mean the sample volume was correct. Direct measurements of the beam geometry done in the laboratory indicated a factor of 4-5 error. This error is apparently due to the larger apparent visible beam diameter versus the actual usable beam diameter given the droplet illumination, chamber optical geometry, microscope optics and film characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 44-45
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  • 17
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    Multi-channel chopper system for a total ozone mapping spectrometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A multi-channel chopper system designed and built to stringent specifications is providing an excellent performance for a total ozone mapping spectrometer (TOMS). State of the art machining technology, suitable material selection, and a way to hold and position the slit plate resulted in the instrument's better than expected performance. A shutter method used for internal calibration allows compensation for the occurrence of an unlikely wavelength shift during testing, launch, or during the orbiting life of the instrument. The TOMS is part of a payload on Nimbus 7 launched on October 24, 1978.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center The 15th aerospace Mech. Symp.; p 63-75
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  • 18
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    Description of the NRL isothermal haze chamber (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In the IHC the critical supersaturation is inferred from the measurement of the size of particles which have grown to their equilibrium size at exactly 100 percent RH. The largest size channel corresponds to a critical supersaturation of 0.014 percent. The growth time required for particles of this size to reach their equilibrium size exceeds the 110 second residence time in the IHC. Since the supersaturation spectrum is always very steep in this region, the contribution of these larger particles which have not yet attained their equilibrium size to smaller size channels is negligible. However, failure of these particles to reach their equilibrium size could result in a significant lowering of the count in the size channel corresponding to the smaller critical supersaturation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 42-43
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  • 19
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    Static diffusion cloud chambers (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The chamber geometry and optical arrangement are described. The supersaturation range is given and consists of readings taken at five fixed points: 0.25%, 0.5%, 0.75%, 1.0%, and 1.25%. The detection system is described including light source, cameras, and photocell detectors. The temperature control and the calibration of the chamber are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 26-27
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  • 20
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    Description and discussion of the NRL TGDCC (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The NRL thermal gradient diffusion cloud chamber (TGDCC) consists of two plates 7.5 cm in diameter separated by 1.25 cm and covered with saturated filter paper. The cylindrical wall separating the plates is glass. The top plate is at room temperature and the bottom plate is cooled with a thermoelectric cooler. The temperature difference is measured with several sets of thermocouples. The CCN concentration was determined from the video recording. This procedure of averaging the maximum count obtained on several successive recordings at the same supersaturation results in concentrations which are somewhat higher than concentrations calculated from an average across the plateau.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 14-16
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  • 21
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    Two-phase flow and heat transfer under low gravity (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Spacelab experiment to investigate two-phase flow patterns under gravity uses a water-air mixture experiment. Air and water are circulated through the system. The quality or the mixture or air-water is controlled. Photographs of the test section are made and at the same time pressure drop across the test section is measured. The data establishes a flow regime map under reduced gravity conditions with corresponding pressure drop correlations. The test section is also equipped with an electrical resistance heater in order to allow a flow boiling experiment to be carried out using Freon II. High-speed photographs of the test section are used to determine flow patterns. The temperature gradient and pressure drop along the duct can be measured. Thus, quality change can be measured, and heat transfer calculated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 43-57
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  • 22
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    Effects of spacecraft motions on fluids experiments (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The equations of motion governing an incompressible fluid contained in an orbiting laboratory were examined to isolate various fictitious forces and their relative influence on the fluid. The forces are divided into those arising from the orbital motions and those arising from small local motions of the spacecraft about its center of mass. The latter dominate the nonrotating experiments. Both are important for rotating experiments. A brief discussion of the onset of time-dependence and violent instability in earth-based rotating and processing systems is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 96-102
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  • 23
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    Comparing dry aerosol size measurements (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Two instruments were used to size dry aerosols for the CCN experiments: the Naval Research Laboratory (NRL) instrument which uses an electrical mobility analyzer to separate the aerosol size fractions and a diffusion chamber to grow and count the particles and the University of Wyoming (WYO) aerosol monitoring system. Measurements from these two systems were usually found to be in agreement during the CCN Workshop. Two examples are presented to compare aerosol size distribution measurements of the two instruments: experiment 8 (monodisperse NaCl) and experiment 27 (polydisperse AgI). Differential (dN/dR) and cumulative plots are shown for both instruments for experiment 8 and experiment 27; also shown are Aitken particle measurements for comparison.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 106-107
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  • 24
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    CCN comparisons of static diffusion chambers (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Nine CCN counters of the static diffusion (SDC) type were compared with one another and with continuous flow diffusion (CFD) chambers. The nine SDCs showed a considerable amount of variation, largely attributable to newness and/or lack of prior calibration of some units. The five more consistent instruments agreed quite well, to within at least 20 percent of the NRL mobility analyzer and to within 10 percent at 1 percent supersaturation. There was satisfactory agreement between the more reliable SDC and CFD chambers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 57-63
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  • 25
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    Diffusion tube (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The diffusion tube was designed to operate below about 0.25 percent of water supersaturation. It is simply a long tube lined on the inside with a damp chamois cloth, and heated isothermally to a few degrees centigrade above the incoming air. The diffusion coefficient for water vapor is slightly larger than that for heat, making it possible to supersaturate the airflow. This is the same principle by which transient supersaturations may occur in parallel plate cloud chambers. Only the diffusion of vapor and heat from the walls into the moving air are considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 37-39
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  • 26
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    A description of the UK Meteorological Office CCN counter (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The chamber is a thermal gradient diffusion type with the upper plate at room temperature and the lower plate thermoelectrically cooled. The light from a 25W projector bulb is focused in a beam of approximations 1x3 mm in the central part of the chamber. The light scattered by drops is viewed in the forward direction (40 deg) by a microscope and a sensitive photodetector. Experiments were performed to relate the peak output from the photocell with the maximum number of drops in the beam recorded photographically. The microscope is used to check the calibration at low concentrations of CCN. The results of the experiments and the performance of the counter are reported.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 33-34
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  • 27
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    Convection in fluids at reduced gravity (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Natural convection is not always harmful and, therefore, to be avoided. In some situations it may be desirable to have fluid flows in space processes, e.g., to stir the fluid phase for mixing and cooling or to help maintain concentration gradients. In may event, it is important to know the extent and nature of convection in space and the factors on which it depends, in order either to minimize the effects to convection, or to utilize the convection to advantage. The information needed to assess both conventional and unstable convection includes: (1) the magnitude and direction of accelerations; (2) geometric configuration; (3) imposed boundary conditions; and (4) material properties.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 69-95
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  • 28
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    Geophysical fluid dynamics (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Systematic scaling or dimensional analysis reveals that certain scales of geophysical fluid flows (such as stellar, ocean, and planetary atmosphere circulations) can be accurately modeled in the laboratory using a procedure which differs from conventional engineering modeling. Rather than building a model to obtain numbers for a specific design problem, the relative effects of the significant forces are systematically varied in an attempt to deepen understanding of the effects of these forces. Topics covered include: (1) modeling a large-scale planetary atmospheric flow in a rotating cylindrical annulus; (2) achieving a radial dielectric body force; (3) spherical geophysical fluid dynamics experiments for Spacelab flights; (4) measuring flow and temperature; and (5) the possible effect of rotational or precessional disturbances on the flow in the rotating spherical containers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Spacecraft Dyn. as Related to Lab. Expt. in Space; p 25-31
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  • 29
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    Analysis of low-g heat transfer for a cryogenic oxygen pressurization heater (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: After the external tank separates from the Orbiter about 2000 pounds of residual liquid oxygen remain in the main propulsion system lines. The pressurization of liquid oxygen from a subcritical to a supercritical state by the use of the heaters of the PRSA tanks while in a low-g environment is investigated. The performance of the heaters while bringing the state of the substance from the subcritical state to the supercritical one is studied, with particular emphasis on the time the pressurization process takes, and the temperature of the heater as the process proceeds.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 38 p
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  • 30
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    Low-power portable geophysical data acquisition system and its use in geomagnetic measurements (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A low-power portable data acquisition system presently in use for geomagnetic measurements is described. The system is composed of a data-processing system containing a low-power microprocessor, a 9-track digital tape recorder, and a rechargeable battery pack. The magnetometer is a low-power three axis fluxgate design. Under program control the data processing system keeps track of time of day and date, samples three analog magnetometer outputs at intervals of either 0.4 or 2 s, digitizes the data to 15-bit resolution, and, depending upon relative magnetic activity, decides upon data compression to increase the tape storage capacity. It also monitors and records internal voltages and provides self-checking functions which may be monitored through a visual readout on the control panel. The system is mounted in a rugged, weather-tight carrying case suitable for use outdoors with minimal protection. The system, including magnetometer, uses 1.6-W power and can store 5.7 Mbytes of data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-19; July 198
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  • 31
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    Vibration of a liquid with a free surface in a spinning spherical tank (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The problem of forced fluid vibrations in a partially filled spinning spherical tank is solved numerically by using the finite element method. The governing equations include Coriolis acceleration and spatially homogeneous vorticity. An exponential instability is detected in the present simulation for fill ratios below 0.5 and centrifugal acceleration to thrust ratios less than 1.7. This fictitious instability appears in the model as a result of the homogeneous vortex assumption since the free slosh equations are neutrally stable in the Liapunov sense.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Sound and Vibration; 76; May 8
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  • 32
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    Solar Maximum Mission Experiment - Ultraviolet Spectroscopy and Polarimetry on the Solar Maximum Mission (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacecraft is described. It is pointed out that the instrument, which operates in the wavelength range 1150-3600 A, has a spatial resolution of 2-3 arcsec and a spectral resolution of 0.02 A FWHM in second order. A Gregorian telescope, with a focal length of 1.8 m, feeds a 1 m Ebert-Fastie spectrometer. A polarimeter comprising rotating Mg F2 waveplates can be inserted behind the spectrometer entrance slit; it permits all four Stokes parameters to be determined. Among the observing modes are rasters, spectral scans, velocity measurements, and polarimetry. Examples of initial observations made since launch are presented.
    Keywords: SOLAR PHYSICS
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    High resolution X-ray spectra of solar flares. V - Interpretation of inner-shell transitions in Fe XX-Fe XXIII (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper examines high-resolution solar flare iron line spectra recorded between 1.82 and 1.97 A by a spectrometer flown by the Naval Research Laboratory on an Air Force spacecraft launched on 1979 February 24. The emission line spectrum is due to inner-shell transitions in the ions Fe XX-Fe XXV. Using theoretical spectra and calculations of line intensities obtained by methods discussed by Merts, Cowan, and Magee (1976), electron temperatures as a function of time for two large class X flares are derived. These temperatures are deduced from intensities of lines of Fe XXII, Fe XXIII, and Fe XXIV. The determination of the differential emission measure between about 12-million and 20-million K using these temperatures is considered. The possibility of determining electron densities in flare and tokamak plasmas using the inner-shell spectra of Fe XXI and Fe XX is discussed.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 245
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    Preliminary observations and results obtained with the ultraviolet spectrometer and polarimeter (1981)
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    Publication Date: 2011-08-18
    Description: New observation with the Ultraviolet Spectrometer and Polarimeter (UVSP) of a number of manifestations of solar activity obtained during the first three months of Solar Maximum Mission operations are presented. Attention is given to polarimetry in sunspots, oscillations above sunspots, density diagnostics of transition-zone plasmas in active regions, and the eruptive prominence - coronal transient link.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 35
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    The solar flare of 1980 March 29 at 0918 UT as observed with the hard X-ray burst spectrometer on the Solar Maximum Mission (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 36
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    Nuclear Science Symposium, 27th, and Symposium on Nuclear Power Systems, 12th, Orlando, Fla., November 5-7, 1980, Proceedings (1981)
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    Publication Date: 2011-08-18
    Description: Advances in instrumentation for use in nuclear-science studies are described. Consideration is given to medical instrumentation, computerized fluoroscopy, environmental instrumentation, data acquisition techniques, semiconductor detectors, microchannel plates and photomultiplier tubes, reactor instrumentation, neutron detectors and proportional counters, and space instrumentation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 37
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    Performance of room temperature mercuric iodide /HgI2/ detectors in the ultralow-energy X-ray region (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Experiments have been done to study the performance of mercuric iodide (HgI2) detectors in the ultralow-energy X-ray region. Energy resolution values of 245 eV (FWHM) for the Mg K-alpha X-ray line at 1.25 keV and 225 eV (FWHM) for the electronic noise linewidth have been obtained for an HgI2 detector with painted carbon contacts using a pulsed-light feedback preamplifier; the whole system was operated at room temperature. The resolution values in the ultralow-energy region are still limited by electronic noise of the system. In an attempt to minimize X-ray attenuation in the front contact, detectors were prepared with thin evaporated Pd contacts. These detectors show a pronounced low-energy tailing of the photopeak below a few keV, in contrast to the spectra obtained by detectors with carbon contact. An attempt has been made to explain the tailing effect starting with models wich have been proposed to describe similar effects in Ge detectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 38
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    On the polarization state of hydromagnetic fluctuations in the solar wind (1981)
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    Publication Date: 2011-08-18
    Description: From presently available observations one can infer that the Alfvenic turbulence measured in the solar wind, predominantly on trailing edges of high-speed streams, is a mixture of modes with two different polarizations, namely, Alfvenic modes and modes which are the incompressible limit of slow magnetosonic waves. Using Helios 2 magnetic data and a variance analysis, parallel (to the mean field) and perpendicular components of the fluctuations are separated, and the possible correlation between such components which would be predicted as a consequence of the incompressible character of the turbulence is studied. Correlations between eigenvalues of the variance matrix are also investigated and discussed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 86; Mar. 1
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  • 39
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    Response of large cavity ion chambers to space protons (1981)
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    Publication Date: 2011-08-18
    Description: The assumption that spherical-shell ion chamber rssponse is equal to the dose in the center of the cavity is found to be a poor approximation for ion chambers used for area monitoring in the space program. The dose response is calculated using the appropriate areal density distribution function. Effects of nuclear reaction are evaluated using proton buildup factors. Errors of up to 100% are found for some components of the space radiation environments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Technology; 52; 1, Ja; Jan. 198
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  • 40
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    Time and energy dependence of heavy ion abundances in solar flare energetic particle events (1981)
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    Publication Date: 2011-08-18
    Description: Examples are presented of the time and energy dependence of the abundances and spectra of the major heavy ions He, C, O and Fe during solar flare events, taken from a survey using the UMD/MPI ULET telescope on IMP-8 during 1973-1977. In some cases, time variations were found in the O/He, O/C and Fe/O ratios which appear to be inconsistent with models based solely on rigidity dependent propagation in the interplanetary medium.
    Keywords: SOLAR PHYSICS
    Type: Contrib. to the 17th Intern. Conf. on Cosmic Rays; p 5-8
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  • 41
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    High-sensitivity circular polarimetry of the Sun, 0.5 - 1.7 microns (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using an isometric (symmetrical) photoelastic-modulator polarimeter and a Cassegrain telescope, broadband polarization measures of the Sun were obtained with unprecedented sensitivity. With an instrumental background of x 10 to the minus 6th power differential effects delta q = V/I of 1 x 10 to the minus 7th power were detectable. Some results: (1) the lambda dependence of broadband circular polarization in spots was observed out to 1.7 mu, extending the visible-light measurements of Illing, Landman, and Mickey. The q drops to of the order of 1 x 10 to the minus 5 power at 1.2 mu (in a strong spot), then rises at 1.6 mu. While molecules or other special mechanisms must play a role in the visible-light polarization, at lambda 1.5 mu the q values seem consistent with gray magneto-opacity. (2) By surveying inactive regions upper limits are set to broadband polarization due to global or deep-seated magnetic fields. For a double-toroidal pattern a differential measure is found, q sub b = (q sub ne + q sub sw - q sub nw - q sub - se) 14, at 1.7 mu, of (+1.2 + or = 0.7) x 10 to the minus 7th power a mean from three series in 1981. Based on a simple estimate by L. Biermann this would correspond to deep-down toroidal fields of or approx 2000 gauss. Extension of this work are discussed.
    Keywords: SOLAR PHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 191-197
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  • 42
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    Solar plages and the interpretation of stellar Ca 2 H and K line variations in late type dwarfs (1981)
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    Publication Date: 2011-08-18
    Description: Approximately a dozen late type dwarf stars have been observed by Wilson (1978) to undergo cyclic variability in Ca II H and K line emission which seems analogous to the solar activity cycle. What might be learned about these stars from solar analogies? The Ca II K index is estimated variation of the Sun viewed as a star, and compared with the observed range of Wilson's stellar observations. Results indicate trends of increasing relative variation H-K(max)/H-K(min) with later spectral type, due to decreasing dilutional contribution of residual photospheric flux to a 1 A band at line center, and of increasing relative variation with decreasing relative time of rise to maximum tau rise/tau reminiscent of the observed solar correlation of a quick rise to sunspot maximum with a strong cycle.
    Keywords: SOLAR PHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 181-189
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  • 43
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    Modification of average coronal properties in the presence of periodic temperature and density variations near the base (1981)
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    Publication Date: 2011-08-18
    Description: Conductive damping of the transient motion of the solar corona, and the consequences on the average flow field of conductively re-distributed energy are discussed. A particular example is treated. First, a steady solution for solar wind flow is found for a given set of steady boundary conditions, between 1.4 and 28 solar radii. These boundary conditions are that the density is 1.6xEO6 cm-3 and the temperature is 1.6xEO6 degrees. The flow profiles for this initial state are those shown at t=0 in the figures. Then, at t=0, periodic, in phase, sinusoidal variations in temperature and density are initiated and continued indefinitely. The amplitudes of the variations are 5 percent and 7.5 percent for the temperature and density respectively, imposed at 1.4 solar radii. The variations have a period of 1 hour shorter than a coronal transit time, but sufficiently long for the disturbances to propagate for small distances (2 to 3 solar radii). These oscillations are like those that might occur for acoustic oscillations, although no explanation is offered as to how an acoustic oscillation might extend to this radius in the first place.
    Keywords: SOLAR PHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 113-120
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  • 44
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    Dynamic phenomena in coronal flux tubes (1981)
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    Publication Date: 2011-08-18
    Description: The study of stellar atmospheres and the determination of specific physical mechanisms, geometries, and magnetic structures by which coronae are maintained is examined. Ultraviolet and soft X-ray components observed in the radiative output of cool stars and the Sun require counterentropic temperature gradients for their explanation. The existence of a hot corona is recognized as a result of mechanical or fluid dynamic effects and the importance of the magnetic field in the heating is accepted. Magnetohydrodynamic energy release associated with the emergence of magnetic flux through the chromosphere and its dynamic readjustment in the corona are major counterentropic phenomena which are considered as primary candidates for corona heating. Systematic plows in coronal flux tubes result from asymmetric heating and systematic flows can exist without substantial chromospheric pressure differences.
    Keywords: SOLAR PHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 53-58
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  • 45
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    Eruptive solar magnetic fields (1981)
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    Publication Date: 2011-08-18
    Description: The quasi-steady evolution of solar magnetic fields in response to gradual photospheric changes is considered, with particular attention given to the threshold of a sudden eruption in the solar atmosphere. The formal model of an evolving, force-free field dependent on two Cartesian coordinates is extended to a field which is not force free but in static equilibrium with plasma pressure and gravity. The basic physics is illustrated through the evolution of a loop-shaped electric current sheet enclosing a potential bipolar field with footpoints rooted in the photosphere. A free-boundary problem is posed and then solved for the equilibrium configuration of the current sheet in a hydrostatically supported isothermal atmosphere. As the footpoints move apart to spread a constant photospheric magnetic flux over a larger region, the equilibria available extend the field to increasing heights.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 251
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  • 46
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    Radio evidence for shock acceleration of electrons in the solar corona (1981)
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    Publication Date: 2011-08-18
    Description: It is pointed out that the new class of kilometer-wavelength solar radio bursts observed with the ISEE-3 Radio Astronomy Experiment occurs at the reported times of type II events, which are indicative of a shock wave. An examination of records from the Culgoora Radio Observatory reveals that the associated type II bursts have fast drift elements emanating from them; that is, a herringbone structure is formed. It is proposed that this new class of bursts is a long-wavelength continuation of the herringbone structure, and it is thought probable that the electrons producing the radio emission are accelerated by shocks. These new events are referred to as shock-accelerated events, and their characteristics are discussed.
    Keywords: SOLAR PHYSICS
    Type: Geophysical Research Letters; 8; Dec. 198
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  • 47
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    Solar wind motion within 30 R solar masses - Spacecraft radio scintillation observations (1981)
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    Publication Date: 2011-08-18
    Description: New remote-sensing observations are reported of the solar wind motion within about 30 earth radii. Use is made of the interplanetary scintillation (IPS) spaced receiver technique with the radio source being a spacecraft signal (rather than a natural radio source as in previous spaced receiver studies). The spacecraft used are Helios A and B and the Viking orbiters. The purposes of the study are (1) to augment the scarce estimates of solar wind bulk flow speed near the sun and in the ecliptic with measurements made using spacecraft signals, and (2) to estimate random velocity components and identify the region where the random velocity is a significant fraction of the mean velocity. In addition, the radial evolution of speed and random velocity is compared with that of the plasma density fluctuation spectrum. Also reported are the first accurately normalized IPS scintillation index measurements using a monochromatic point source.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 103; 2, No; Nov. 198
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  • 48
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    The structure and dynamics of the heliospheric current sheet (1981)
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    Publication Date: 2011-08-18
    Description: It has been suggested that the sector structure observed in the interplanetary magnetic field may be interpreted in terms of a warped equatorial current sheet in the heliosphere. The reported study seeks to investigate this suggestion and to provide a clear picture of the topology of the current sheet. An analysis is presented of the magnetic field data obtained by the Pioneer 10 and 11 spacecraft during the time from 1972 to 1976, taking into account a range of heliocentric distances from 1 to 8.5 AU. The single most convincing observation in support of the warped current sheet hypothesis is the almost complete disappearance of the sector structure in the Pioneer 11 data when the spacecraft reaches a heliographic latitude of 16 deg in 1976. The observation suggests that the spacecraft was consistently above the current sheet for a period of several months.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 86; Dec. 1
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  • 49
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    Heat transfer in cooled porous region with curved boundary (1981)
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    Publication Date: 2011-08-18
    Description: Heat transfer characteristics are analyzed for a cooled two-dimensional porous medium having a curved boundary. A general analytical procedure is given in combination with a numerical conformal mapping method used to transform the porous region into an upper half plane. To illustrate the method, results are evaluated for a cosine shaped boundary subjected to uniform external heating. The results show the effects of coolant starvation in the thick regions of the medium, and the extent that internal heat conduction causes the heated surface to have a more uniform temperature.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    The field and plasma configuration of a filament overlying a solar bipolar magnetic region (1981)
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    Publication Date: 2011-08-18
    Description: This paper presents an analytic model for a finite-size straight filament suspended horizontally in a steady state over a bipolar magnetic region. The equations of magnetostatic equilibrium are integrated exactly. The solution obtained illustrates the roles played by the electric current, magnetic field, pressure, and plasma weight in the balance of force everywhere in space. A specific example of a filament of diameter 50,000 km, with a density two orders of magnitude over the corona and supported by a magnetic field of about 4 gauss is included. The filament temperature can take values ranging from a small fraction to a few times the coronal temperature, depending on the internal electric current of the filament. To produce a cool filament, such as the quiescent prominence, the solution is required to have an internal field with a strong component along the filament, giving rise to helical structures. A hot filament such as the X-ray coronal loop can be produced as a twisted magnetic flux tube embedded in a strong background field aligned parallel to the filament and having lower density and temperature. The basic steps of construction can be used to develop models more realistic than the ones presented for their analytic simplicity.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 246
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    Interactive method for computation of viscous flow with recirculation (1981)
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    Publication Date: 2011-08-18
    Description: An interactive method is proposed for the solution of two-dimensional, laminar flow fields with identifiable regions of recirculation, such as the shear-layer-driven cavity flow. The method treats the flow field as composed of two regions, with an appropriate mathematical model adopted for each region. The shear layer is computed by the compressible boundary layer equations, and the slowly recirculating flow by the incompressible Navier-Stokes equations. The flow field is solved iteratively by matching the local solutions in the two regions. For this purpose a new matching method utilizing an overlap between the two computational regions is developed, and shown to be most satisfactory. Matching of the two velocity components, as well as the change in velocity with respect to depth is amply accomplished using the present approach, and the stagnation points corresponding to separation and reattachment of the dividing streamline are computed as part of the interactive solution. The interactive method is applied to the test problem of a shear layer driven cavity. The computational results are used to show the validity and applicability of the present approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 40; Apr. 198
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  • 52
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    Bowen fluorescence on the sun (1981)
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    Publication Date: 2011-08-18
    Description: An identification is made of a weak line in the high-resolution EUV solar spectrum, and the contribution of the Bowen fluorescence mechanism to line emission is considered. The line at 303.625 A is noted to coincide with the 2p 3d(3P2 0) - 2p2(3P1) transition of O III at 303.621 A, which could be excited by He II line excitation of the O III 2p2(3P2) - 2p 3d(3P2 0) transition at 303.799 A. Computations of the collisionally induced intensities of the 2p2(3P) - 2p3d(3P 0) multiplet are shown to result in values not observed in the solar spectrum, indicating that Bowen fluorescence, rather than collisional excitation, is the source of the line. The Bowen fluorescence mechanism is noted to have implications for the identification of other spectral lines, and for models of the solar corona.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 53
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    Large-eddy simulation of the shear-free turbulent boundary layer (1981)
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    Publication Date: 2011-08-18
    Description: The shear-free turbulent boundary layer is calculated by the large-eddy simulation technique. The filtered Navier-Stokes equations are used; the method of integration employs Fourier expansions in the homogeneous directions and finite differences in the cross-stream direction. Results indicate that the simulation is capable of predicting the primary Reynolds-number effects.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 103; Feb. 198
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  • 54
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    Deviation-free Bragg cell frequency-shifting (1981)
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    Publication Date: 2011-08-18
    Description: A method is described of applying a variable frequency-shift to a laser beam, by means of Bragg cells, in which the direction of the output diffracted beam is unaffected by the magnitude of the applied shift. Applications of the technique to reference-beam and Doppler-difference forms of laser anemometry are discussed together with methods of obtaining increased dynamic range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Feb. 15
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    Selection of fluorescence lidar operating parameters for SNR maximization (1981)
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    Publication Date: 2011-08-18
    Description: Fluorescence lidar when applicable offers one of the most sensitive methods for measuring the concentration of trace constituents of the atmosphere. In the conduct of a fluorescence lidar experiment, a number of parameters which can be used to optimize the SNR can be controlled. In this paper the optimum division of laser pulses centered on and off the fluorescence excitation wavelength is calculated as a function of the ratio of the fluorescence signal strength to the strength of fluorescence from interfering species. For strong interference signals the time should be divided equally on and off the line. For strong fluorescence signals the time on line is proportional to the square root of the on-line off-line signal ratio. The optimization of the integration time for varying values of signal-to-background and signal-to-interference ratios, atmospheric attenuation, laser energy variations, background measurement time, and on-line off-line time division is also considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Feb. 15
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    Remote Raman measurement techniques (1981)
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    Publication Date: 2011-08-18
    Description: The use of laser Raman measurement techniques in remote sensing applications is surveyed. A feasibility index is defined as a means to characterize the practicality of a given remote Raman measurement application. Specific applications of Raman scattering to the measurement of atmospheric water vapor profiles, methane plumes from liquid natural gas spills, and subsurface ocean temperature profiles are described. This paper will survey the use of laser Raman measurement techniques in remote sensing applications using as examples specific systems that the Computer Genetics Corporation (CGC) group has developed and engineered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Jan
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    Measuring molecular flows with high-resolution stimulated Raman spectroscopy (1981)
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    Publication Date: 2011-08-18
    Description: It is proposed to use high-resolution stimulated Raman spectroscopy to directly measure high-speed molecular flow velocities in wind tunnels and in combustive chambers. A feasibility study indicates that flow speeds from Mach 0.04 up may be measured with the proposed method using available laser systems. It is pointed out that the success of the proposed technique will make it possible to measure all interesting flow parameters, i.e., species concentration, temperature, and velocity, in a time of less than 1 microsecond at a repetition rate of 10,000/s using a single experimental arrangement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Journal of Quantum Electronics; QE-17; Jan. 198
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  • 58
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    Latitude dependence of solar wind velocity observed at not less than 1 AU (1981)
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    Publication Date: 2011-08-18
    Description: The large-scale solar wind velocity structure in the outer heliosphere has been systematically analyzed for Carrington rotations 1587-1541 (March 1972 to April 1976). Spacecraft data were taken from Imp 7/8 at earth, Pioneer 6, 8, and 9 near 1 AU, and Pioneer 10 and 11 between 1.6 and 5 AU. Using the constant radial velocity solar wind approximation to map all of the velocity data to its high coronal emission heliolongitude, the velocity structure observed at different spacecraft was examined for latitudinal dependence and compared with coronal structure in soft X-rays and H-alpha absorption features. The constant radial velocity approximation usually remains self-consistent in decreasing or constant velocity solar wind out to 5 AU, enabling us to separate radial from latitudinal propagation effects. Several examples of sharp nonmeridional stream boundaries in interplanetary space (about 5 deg latitude in width), often directly associated with features in coronal X-rays and H-alpha were found.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 86; Jan. 1
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  • 59
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    Annular apertures with low and high obstruction (1981)
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    Publication Date: 2011-08-18
    Description: The distribution of image energy by the central obstruction of annular apertures is discussed with special emphasis on the effect of an aperture shape parameter which can be interpreted optically as the inverse obstruction ratio. This parameter generates group arrangements with the number of rings given by N2 = 1/a, where a is the central obstruction ratio.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Jan. 15
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  • 60
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    A molecular model for ice nucleation and growth, attachment 1 (1981)
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    Publication Date: 2011-08-18
    Description: The quantum mechanical technique is used to study ionic, configurational, and impurity defects in the ice surface. In addition to static calculations of the energetics of the water monomer-ice surface interactions, molecular dynamics studies were initiated. The calculations of the monomer-ice surface interaction, molecular dynamics studies were initiated. The calculations of monomer-ice surface interactions indicate that many adsorption sites exist on the ice surfaces and that the barriers between bonding sites are relatively low. Bonding on the prism face of ice is preferentially above lattice sites.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: A Mol. Model for Ice Nucleation and Growth; 27 p
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    A molecular model for ice nucleation and growth, attachment 2 (1981)
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    Publication Date: 2011-08-18
    Description: The central field empirical pair potential model is applied to studying the effects of kinks, ledges, and vacancies on the absorption of water molecules from the vapor. Molecular dynamics simulations indicate that cluster and/or surface modes play a primary role in the absorption process, the flexibility of the hydrogen bond serves to decrease the energy required for structural interconversion, and the rapid distribution of added energy in a hydrogen bonded system lead to aggregate stability which greatly exceeds that predicted by static energy calculations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: A Mol. Model for Ice Nucleation and Growth; 22 p
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    Report of the panel on fluid dynamics (1981)
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    Publication Date: 2011-08-18
    Description: Areas of investigation in fluid dynamics, recommended experiments, and use of the facility for theory evaluation are discussed. Tunnel flow quality and calibration of the NTF are considered. Recent technological advances affecting tunnel design are surveyed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: High Reynolds Number Res. - 1980; p 169-195
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    Temperature stabilized phase detector (1981)
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    Publication Date: 2011-08-18
    Description: The construction, tests, and performance of a temperature stabilized phase detector are discussed. It has a frequency stability of 5 parts in 10 to the 16th power at 100 MHz, with a temperature step of 20 C (15 to 35 C).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 90-95
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  • 64
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    ORION: Microwave water vapor radiometer subsystem design (1981)
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    Publication Date: 2011-08-18
    Description: Electrical path delay caused by atmospheric water vapor may be a limiting error source for geodetic measurements made with VLBI. Direct measurement of atmospheric water vapor is necessary to obtain path delay correction required by the ORION project. A dual channel water vapor radiometer is described which operates at frequencies near the 22 GHz water vapor line and is capable of collecting data that permits calculation of path delay within 2 cm accuracy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Telecommun. and Data Acquisition; p 10-14
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  • 65
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    Flux vector splitting of the inviscid gasdynamic equations with application to finite-difference methods (1981)
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    Publication Date: 2011-08-18
    Description: The conservation-law form of the inviscid gasdynamic equations has the remarkable property that the nonlinear flux vectors are homogeneous functions of degree one. This property readily permits the splitting of flux vectors into subvectors by similarity transformations so that each subvector has associated with it a specified eigenvalue spectrum. As a consequence of flux vector splitting, new explicit and implicit dissipative finite-difference schemes are developed for first-order hyperbolic systems of equations. Appropriate one-sided spatial differences for each split flux vector are used throughout the computational field even if the flow is locally subsonic. The results of some preliminary numerical computations are included.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 40; Apr. 198
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  • 66
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    Dynamics of solar cosmic ray events - Processes at large heliocentric distances /much greater than 1 AU/ (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of solar cosmic ray events at heliocentric distances up to 6 AU and beyond obtained by the Pioneer 10 and 11 spacecraft are discussed in terms of the propagation of energetic charged particles in interplanetary space. Following a review of the diffusion propagation model used to explain cosmic ray transport, the statistical studies of McCarthy and O'Gallagher (1976) and Zwickl and Webber (1977) of the relations of event parameters with radial distance and the simultaneous observation studies of Hamilton (1977) are reviewed, and it is noted that the results imply a slowly increasing radial diffusion coefficient out to about 6 AU. More recent analyses of data obtained at heliocentric distances greater than 10 AU are then presented which indicate that the coefficient of radial diffusion may actually be decreasing with radial distance beyond 5 AU. Finally, theoretical predictions of the radial variation of the diffusion coefficient are presented which take into account the background interplanetary medium and are shown to be in agreement with observations.
    Keywords: SOLAR PHYSICS
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  • 67
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    Photospheric subrotations, differential rotation and zonal wind bands - A reverse pirouette (1981)
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    Publication Date: 2011-08-18
    Description: It is noted that on the sun the core is assumed to be rotating with a period of about 12 days while the overlying 'mantle' convection zone has a solid body component of about 27 days. It is proposed that this phenomenon could simply be understood as a 'reverse pirouette'. It is noted that while previously proposed models provide solutions of valid equations and computer analyses, they lack a simple physical picture to explain the phenomenon. In the model proposed here, the solar oblateness is conventionally providing added heat input at the poles. The result is the large scale transport of material toward the equator, causing subrotation. The model is thus seen as facilitating an understanding of the formation of a slowly rotating convection zone above the more rapidly rotating core. The latitudinal photospheric differential rotation is interpreted as a 'second order' effect associated with the horizontal transport of momentum.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 71; May 1981
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    Fast plasma heating by anomalous and inertial resistivity effects in the solar atmosphere (1981)
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    Publication Date: 2011-08-18
    Description: A simple model is presented to describe fast plasma heating by anomalous and inertial resistivity effects. It is noted that a small fraction of the plasma contains strong currents that run parallel to the magnetic field and are driven by an exponentiating electric field. The anomalous character of the current dissipation derives from the excitation of electrostatic ion-cyclotron and/or ion-acoustic waves. The possible role of resistivity deriving from geometrical effects ('inertial resistivity') is also considered. Using a marginal stability analysis, equations for the average electron and ion temperatures are derived and numerically solved. No loss mechanisms are taken into account. The evolution of the plasma is described as a path in the drift velocity diagram, where the drift velocity is plotted as a function of the electron to ion temperature ratio.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 245
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  • 69
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    The corona associated with solar filaments (1981)
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    Publication Date: 2011-08-18
    Description: Spectroheliograms in high temperature ions such as Fe XV show the existence of both filaments that are brighter than the ambient corona and filaments that are darker than the ambient corona. The relationship of the filaments to photospheric magnetograms is described, and a possible physical mechanism to explain the differences is discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 71; May 1981
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  • 70
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    Apparatus for high-pressure and low-temperature experiments (1981)
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    Publication Date: 2011-08-18
    Description: A new type of apparatus for high-pressure experiments at low temperature (1.5 K) is presented. It uses a flat diamond anvil with a spherical indentor. It utilizes a load ring placed under the sample, so that the load (and hence pressure) can be measured in situ at low temperature. The apparatus was successfully used to investigate the high-conductivity state of sulphur. It can be used to investigate other thin film samples.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Feb. 198
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  • 71
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    Telecentric optical system for observing daytime chemical releases at high altitudes (1981)
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    Publication Date: 2011-08-18
    Description: A system to be used for the tracking of high altitude chemical releases in the presence of a bright daytime sky is described. The system uses telecentric optics, a tilting filter, a solid state image sensor, and a real time digital processor to produce the release image. Field test data are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Mar. 15
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  • 72
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    Flares and dynamic aspects (1981)
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    Publication Date: 2011-08-18
    Description: Theory of the dynamic nature of solar flares, eruptive prominences, and coronal transients is surveyed. Two types of flare are considered: compact eruptions (small flares) which are probably loops, and large eruptions of double filament flares. The physical sense of this classification is justified, using solar observations. Even leaving the question unanswered of whether a coronal transient is a loop of ejected matter or a shock wave, the important, perhaps fundamental, role of mass motion in flare physics is evidenced.
    Keywords: SOLAR PHYSICS
    Type: Obs. de Paris-Meudon Forum on Solar Activity; 13 p
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  • 73
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    The coronal and interplanetary current sheet in early 1976 (1981)
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    Publication Date: 2011-08-18
    Description: A comparison of Helios 1 and 2 observations of the interplanetary sector pattern in early 1976 with the maximum brightness curves in the K coronameter data at 1.5 solar radii shows that the latter may be identified with the footprints of the sector boundary surface to an accuracy of about 10 deg. The sector boundary surface probably extended to about 15 deg in the Northern Hemisphere and to about 30 deg in the Southern Hemisphere, with little change between 1.5 solar radii and 1 AU. The surface was warped appreciably from a single titled plane (a dipole configuration) suggesting a significant magnetic quadrupole contribution.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 86; Oct. 1
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  • 74
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    Automated analyzer for aircraft measurements of atmospheric methane and total hydrocarbons (1981)
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    Publication Date: 2011-08-18
    Description: An automated methane/total hydrocarbon analyzer is presented, which can produce alternate methane/total hydrocarbon measurements every 7 seconds to provide the spatial resolution required for regional hydrocarbon measurements at aircraft speeds. The construction and sampling techniques developed for the aircraft mounted system are discussed. A technique to periodically measure atmosphere oxygen is incorporated into the analyzer to ensure accurate hydrocarbon measurements, and a data collection methodology is developed to minimize errors resulting from changes in flame ionization detector sensitivity at different altitudes. Aircraft data acquired at the 1979 Southeastern Virginia Urban Plume Study are also presented, which illustrate the application of the instrument to a troposphere pollution plume.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Oct. 198
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  • 75
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    Multichannel scanning radiometer for remote sensing cloud physical parameters (1981)
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    Publication Date: 2011-08-18
    Description: A multichannel scanning radiometer developed for remote observation of cloud physical properties is described. Consisting of six channels in the near infrared and one channel in the thermal infrared, the instrument can observe cloud physical parameters such as optical thickness, thermodynamic phase, cloud top altitude, and cloud top temperature. Measurement accuracy is quantified through flight tests on the NASA CV-990 and the NASA WB-57F, and is found to be limited by the harsh environment of the aircraft at flight altitude. The electronics, data system, and calibration of the instrument are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Oct. 198
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    On the theory of coronal heating mechanisms (1981)
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    Publication Date: 2011-08-18
    Description: The present state-of-the-art of two classes of theories of coronal heating is examined: (1) heating by acoustic processes in the 'nonmagnetic' parts of the atmosphere (the shock-wave theory is an example); and (2) heating by electrodynamic processes in the magnetic regions of the corona (beta much less than 1) either by MHD waves or current heating in regions with high electric current densities (flare-type heating). It is concluded that the mechanism of the heating of the solar chromosphere and corona remains an open question, especially in explaining detailed atmospheric structures. The acoustic theory might be correct with little modification for most of the chromosphere, but as soon as the atmosphere shows a high degree of structure as in the corona and transition layer the magnetic field must play a dominant role. It appears that the current heating theories have a small range of applicability, while the MHD-wave theories are the most promising.
    Keywords: SOLAR PHYSICS
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    Noise effects in an optical heterodyne spectrometer using tunable diode lasers (1981)
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    Publication Date: 2011-08-18
    Description: A comparison of measured and predicted signal-to-noise ratio is made in an optical heterodyne spectrometer utilizing a tunable diode laser which exhibited excess noise. It is shown that good agreement between predicted and measured signal-to-noise ratios results if excess noise effects due to tunable diode lasers are included in the predictions. The methods used to quantify excess noise and to incorporate their effects into predictions of signal-to-noise ratio are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters; 39; Nov. 1
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  • 78
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    Identification of new solar OH lines in the 10-12 micron region (1981)
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    Publication Date: 2011-08-18
    Description: High-resolution (0.02/cm) infrared solar spectra obtained with a balloon-borne interferometer reveal new solar absorption features, which appear as regularly spaced quartets, in the 825-960/cm region. The lines are interpreted as high N-double-prime (25-33) pure rotation lines of solar OH. An effective amount of approximately 8 x 10 to the 15th molecules/sq cm of OH is estimated from the spectra.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 248
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  • 79
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    Satellite oceanography - The instruments (1981)
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    Publication Date: 2011-08-18
    Description: It is pointed out that no instrument is sensitive to only one oceanographic variable; rather, each responds to a combination of atmospheric and oceanic phenomena. This complicates data interpretation and usually requires that a number of observations, each sensitive to somewhat different phenomena, be combined to provide unambiguous information. The distinction between active and passive instruments is described. A block diagram illustrating the steps necessary to convert data from satellite instruments into oceanographic information is included, as is a diagram illustrating the operation of a radio-frequency radiometer. Attention is also given to the satellites that carry the various oceanographic instruments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Oceanus; 24; Fall 198
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    Schlieren with a laser diode source (1981)
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    Publication Date: 2011-08-18
    Description: The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Sept
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  • 81
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    On ionization equilibrium in solar flares as determined from X-ray emissionlines of Ca XVIII and Ca XIX (1981)
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    Publication Date: 2011-08-18
    Description: A diagnostic capable of determining the state of ionization equilibrium in flare plasmas is important for the determination of the physical conditions in flares. An experiment on the Air Force satellite P78-1 has provided high-resolution X-ray spectra which make it possible to determine the state of the ionization equilibrium in coronal flare plasmas. The considered investigation has the objective to show that the interpretation of the calcium results is complicated by several possible blends to line q, and to point out a variation in the observed ratios which seems difficult to account for. Possible explanations for the observations are discussed, taking into account the possibility that the ionization equilibrium calculations have to be improved. Another possible explanation is related to a suggestion made by Urnov (1981) and Karev et al. (1980) concerning the effects produced by the presence of high-energy nonthermal electrons.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 251
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    Solar observations and atomic data for the 3s2 1s0-3s3p 3P1 transition in S v (1981)
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    Publication Date: 2011-08-18
    Description: High resolution solar observations of the S v intersystem line at 1199.18 A are available from Skylab. This line is potentially useful as a density diagnostic for high density plasmas expected in solar flares. S v lines are also prominent in solar spectra at wavelengths below 1000 A. Collision strengths and radiative decay rates are calculated for levels of the configurations 3 s2, 3s3p, 3p2, and 3s3d. Level populations for the five lowest energy levels have been calculated as a function of electron density. These calculations are carried out assuming the temperature at which S v is most abundant in solar plasmas. The calculated population of the 3s3p 3P1 level reaches a pseudo-Boltzmann equilibrium at a density which is about five times higher than is derived from solar spectra and previous density determinations. It is believed that the discrepancy is due to a significant contribution from resonances to the 3s2-3s3p 3P excitation rate coefficient. It is suggested that the contribution of the resonances to the S v excitation rate coefficient can be estimated from a comparison of the experimental results and the theoretical calculations.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 250
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  • 83
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    Spectral energy transfer for inhomogeneous turbulence (1981)
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    Publication Date: 2011-08-18
    Description: It is noted that several terms in the two-point spectral equation for homogeneous turbulence can be interpreted as spectral-transfer terms; that is, they represent the net rate of energy transfer into a wavenumber region from all other wavenumbers. This holds for terms associated with both turbulence and self-interaction and interaction between turbulence and mean gradients. It is not seen as obvious, however, that similar interpretations apply when the turbulence is not homogeneous. In particular, one might question the interpretation for the terms associated with turbulence self-interaction because the condition of homegeneity is generally used in making the interpretation. It is the purpose here to consider whether terms interpretable as transfer terms exist in the equations for inhomogeneous turbulence. It is found that certain terms in the two-point spectral equation can be interpreted as transfer terms.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 24; Oct. 198
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    Distorted turbulence in axisymmetric flow (1981)
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    Publication Date: 2011-08-18
    Description: A solution to the rapid-distortion theory for small-scale turbulence in flow round an axisymmetric obstacle is derived. General formulae for velocity covariances and Eulerian time scales are obtained and are evaluated for the particular case of flow round a sphere. The large-scale limit for this flow is also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Quarterly Journal of Mechanics and Applied Mathematics; 34; Nov. 198
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    Hollow cathode startup using a microplasma discharge (1981)
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    Publication Date: 2011-08-18
    Description: Attention is given to a microplasma discharge to initiate a hollow cathode discharge for such applications as plasma flow experiments, the electric propulsion of space vehicles, and as a replacement for filament cathodes in neutral beam injector ion sources. The technique results in a cathode that is easy to start, simple in design, and which does not require external RF exciters, inserts or heating elements. Future applications may include ion beam milling and ion implantation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Aug. 198
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  • 86
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    Improved formula for continuous-wave measurements of ultrasonic phase velocity (1981)
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    Publication Date: 2011-08-18
    Description: An improved formula for continuous-wave ultrasonic phase velocity measurements using contact transducers is derived from the transmission line theory. The effect of transducer-sample coupling bonds is considered for measurements of solid samples even though it is often neglected because of the difficulty of accurately determining the bond thickness. Computer models show that the present formula is more accurate than previous expressions. Laboratory measurements using contacting transducers with the present formula are compared to measurements using noncontacting (hence effectively correction-free) capacitive transducers. The results of the experiments verify the validity and accuracy of the new formula.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Physics; 52; May 1981
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    Solar variability (1981)
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    Publication Date: 2011-08-18
    Description: Reference is made to direct measurements carried out by space-borne detectors which have shown variations of the solar constant at the 0.2 percent level, with times scales ranging from days to tens of days. It is contended that these changes do not necessarily reflect variations in the solar luminosity and that, in general, direct measurements have not yet been able to establish (or exclude) solar luminosity changes with longer time scales. Indirect techniques, however, especially radius measurements,suggest that solar luminosity variations of up to approximately 0.7 percent have occurred within a period of tens to hundreds of years.
    Keywords: SOLAR PHYSICS
    Type: (ISSN 0185-1101)
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    Multivalued velocity field model of turbulence (1981)
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    Publication Date: 2011-08-18
    Description: The considered study is based on new theoretical concepts regarding a post-instability model of a fluid discussed by Zak (1980). The model permits the completion of the governing equations of turbulence by introducing multivalued fields of velocities. Attention is given to the mechanism of energy dissipation, the characteristic wave propagation, a simplified model, the formation of turbulence around stagnation points, the formulation of boundary conditions, and the mechanism of turbulence formation. The mechanism of turbulence formation can be understood as propagation of initial discontinuities from the boundaries into a flow with the characteristic velocity which is defined by the normal (to the boundary) velocity components. These components emerge at the boundary as a result of jumps in the tangential components due to the continuity equation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Mechanics Research Communications; 8; 2, 19; 1981
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    Magnetic loop behind an interplanetary shock - Voyager, Helios, and IMP 8 observations (1981)
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    Publication Date: 2011-08-18
    Description: The flow behind an interplanetary shock was analyzed through the use of magnetic field and plasma data from five spacecraft, with emphasis on the magnetic cloud identified by a characteristic variation of the latitude angle of the magnetic field. The size of the cloud was found to be about 0.5 AU in radial extent and greater than 30 deg in azimuthal extent, with its front boundary almost normal to the radial direction. Because the field direction of the magnetic cloud as it moved past the spacecraft was observed to rotate nearly parallel to a plane, it is thought that the field configuration of the cloud was essentially two-dimensional. These results further suggest that the lines of force in the magnetic cloud formed loops, but it could not be determined whether these loops were open or closed.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research; 86; Aug. 1
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  • 90
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    On the mixing of a rectangular jet (1981)
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    Publication Date: 2011-08-18
    Description: Hot-wire measurements in an incompressible rectangular jet, issuing into a quiet environment at ambient conditions, are presented. A blow-down-type air supply system was used to provide the airflow to a cylindrical settling chamber 1.75 m in length and 0.6 m in diameter. The measurements were made with constant-temperature anemometers in conjunction with linearizers. The two signals from the linearizers were sent through a sum and difference unit which was calibrated from dc to 100 kHz. The distributions of mean velocity and the turbulence shear stresses were measured in the two central planes of the jet stations up to 115 widths downstream of the nozzle exit. Three distinct regions characterized the jet flow field: a potential core origin, a two-dimensional-type region, and an axisymmetric type region. The onset of the second region appeared to be at a location where the shear layers separated by the short dimension of the nozzle meet; and the third region occurred at a downstream location where the two shear layers from the short edges of the nozzle meet. In the central plane, similarity was found both in the mean velocity and shear stress profiles beyond 30 widths downstream of the nozzle exit; profiles of rms velocity showed similarity in the second, but not the third region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 107; June 198
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    Real-time observation of X-ray diffraction patterns with the Lixiscope (1981)
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    Publication Date: 2011-08-18
    Description: The feasibility of the Lixiscope (Low Intensity X-ray Imaging Scope) is demonstrated for real-time observation of transmission Laue patterns. Making use of the high-gain capability of microchannel plate (MCP) visible-light image intensifier tubes, X-ray images are converted to visible-light images by a scintillator. Pb discs are taped to the center of the Lixiscope input face, and crystal samples are held on a goniometer stage with modeling clay. With a compact size to facilitate off axis viewing, and real-time viewing to allow instantaneous response, the Lixiscope may prove useful in dynamic studies of the effects of plastic flows, stresses, high pressures, and low temperatures.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; July 198
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  • 92
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    Gauge calibration system based on piston manometer (1981)
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    Publication Date: 2011-08-18
    Description: An unbaked calibration system is described that permits absolute calibration with a piston manometer in the range 0.0002 to 6 Pa, with a probable error of 5 microPa + 0.8%, or in the range 0.00008 to 0.02 Pa, with a probable error of 2 microPa + 1%. Procedures and techniques that permit this performance are detailed. For hot-cathode ion gauges, the magnitudes of systematic corrections for envelope temperature and grid current are also indicated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Vacuum Science and Technology; 19; July-Aug
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  • 93
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    Radiometric performance of the test-bed aircraft multispectral scanner /TBAMS/ system (1981)
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    Publication Date: 2011-08-18
    Description: Laboratory and flight radiometric performance testing of an experimental multispectral scanner system is described. High sensitivity performance is confirmed by test results using noise equivalent spectral radiance as the primary figure of merit. A performance comparison between the test-bed aircraft multispectral scanner (TBAMS) and the Bendix modular multispectral scanner (M2S) is presented. Methods for achieving high sensitivity operation are discussed as well as some of the practical implications of such operation for flight remote sensing experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Sept
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  • 94
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    Coronal activity below 2 solar radii - 1980 February 15-17 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Coronal observations concerning the area between the solar surface and 2.0 solar radii can now be conducted by making use of a new ground-based K-coronameter and a prominence monitor on Mauna Loa in Hawaii. Observations made by the K-coronameter on three consecutive days surrounding the eclipse of 1980 February 16 show that the solar corona was very active during this time. Definite changes occurred between each day's observations. During one period of K-coronameter observations (1980 February 15) a coronal transient was observed to move through the coronameter's field of view. A description is presented of the general changes which occurred in the corona during this period, taking into account the coronal transient observed by the prominence monitor and K-coronameter. The most important aspects of these new observations pertain to the relationship between the H alpha prominence and the surrounding coronal material.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 246
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  • 95
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    Determination of solar proton fluxes and energies at high solar latitudes by UV radiation measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The latitudinal variation of the solar proton flux and energy causes a density increase at high solar latitudes of the neutral gas penetrating the heliosphere. Measurements of the neutral density by UV resonance radiation observations from interplanetary spacecraft thus permit deductions on the dependence of the solar proton flux on heliographic latitude. Using both the results of Mariner 10 measurements and of other off-ecliptic solar wind observations, the values of the solar proton fluxes and energies at polar heliographic latitudes are determined for several cases of interest. The Mariner 10 analysis, together with IPS results, indicate a significant decrease of the solar proton flux at polar latitudes.
    Keywords: SOLAR PHYSICS
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  • 96
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    Absolute S- and P-plane polarization efficiencies for high frequency holographic gratings in the VUV (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High frequency plane gratings (3500 and 3600 gr/mm) have been holographically ruled and blazed for the VUV spectral region. All gratings were coated with 70 nm Al + 25 nm MgF2. Absolute unpolarized and S- and P-plane polarization efficiencies have been measured for the first and second orders in the 120- to 450-nm spectral region at 18.5 and 30 deg angles of deviation. For deep grooves, anomalous features are more pronounced for the P-plane polarization efficiency than for the S-plane polarization efficiency. Holographic gratings can be tailored to produce high polarization or low polarization in the VUV. For comparison, efficiencies and polarization of the best conventional high frequency gratings were also determined. Measurements show that scattered light is significantly lower for holographic gratings in the VUV when compared with the conventional gratings.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; May 15
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  • 97
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    What produces the high densities observed in solar flare plasmas (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is drawn to the implications of the high densities observed in flare plasmas in the wide temperature range from 10 to the 4th K to more than 10 to the 7th K. The chromospheric evaporation theory for the decay phase is discussed, and it is found that it is not consistent with the observations. It is pointed out that all the flare mechanisms proposed so far, e.g., magnetic field reconnection in various geometries, have entirely ignored the fundamental problem of how the high densities arise in the first place, and, in fact, they are unable to answer this question. It is suggested that compressional heatings of a flaring loop might be responsible for the density and emission measure (EM) increases observed in flare plasmas. Chromospheric evaporation associated with local heating in the initial rising phase of the flare, in distinction to the existing evaporation theory which assumes a coronal heating source, is also discussed. Possible observational tests, utilizing the newly launched Solar Maximum Mission (SMM) satellite, are presented.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics; 97; 1, Ap; Apr. 198
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  • 98
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    Observations of solar flares on 1980 April 30 and June 7 with the hard X-ray burst spectrometer (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Descriptions of hard X-ray observations for solar flares occurring on 1980 April 30 and June 7 are presented. The hard X-ray light curve for the June 7 event shows complex intensity variations on time scales of 100 ms and spectral variations on time scales of seconds. The results for the 1980 April 30 flare are compared with simultaneous observations from other SMM instruments and from ground-based observatories. These comparisons have enhanced the interpretation of the hard X-ray data for this event and have permitted the tentative identification of the origin of the hard X-ray emission with a small loop structure within the flare region.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 99
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    Observations of the 1980 April 30 limb flare by the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of the M2 limb flare of 1980 April 30 by the ultraviolet spectrometer and polarimeter in the C IV 1548 A line are described and compared with observations from other SMM instruments and with ground-based H-alpha data. Events observed during the 18 minutes leading up to the flare impulsive phase include the filling of a small loop with material moving at about 20 km/s, followed by a rapid brightening in C IV, H-alpha, and hard X-rays, with a subsequent brightening of a higher set of loops. The rapid brightening appears to be at the junction of the small loop with the overlying magnetic structures, which suggests the flare may be caused by their interaction.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 100
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    A study of low-noise preamplifier systems for use with room temperature mercuric iodide /HgI2/ X-ray detectors (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An analysis of different preamplification systems for use with room temperature mercuric iodide X-ray detectors has been performed. Resistor-, drain-, and light-feedback preamplifiers have been studied. Energy resolution values of 295 eV (FWHM) for an Fe-55 source (5.9 keV) and 225 eV (FWHM) for a pulser have been obtained with both the detector and the input FET at room temperature using a pulsed-light feedback preamplifier. Improvement in energy resolution by cooling the input FET using a small Peltier element has been discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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