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At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

A relationship between synchronous-altitude electron fluxes and the auroral electrojet, appendix A

Simultaneous observations during four substorms are reported from the Lockheed auroral particle spectrometer on ATS-5 and the University of Alberta meridian magnetometer chain (Canada). During the four events studied, there was a good correlation between the magnitude of the trapped electron fluxes in the energy range from 1.8 to 53 keV and the magnitude of the electrojet current as measured by a station in the magnetometer chain at a latitude close to that expected for the ATS conjugate point. The Hall effect was studied and a model electrojet was constructed which gave a good absolute agreement between the two measured quantities. The results are consistent with the convection electric field remaining approximately constant during a substantial portion of each of the substorms studied. The temporal variations of the electrojet were apparently controlled by conductivity changes in the ionosphere as determined by the precipitating auroral electrons.

Sharp, R. D.↗
NASA NTRS1976

Aeronomy report no. 73: Analysis of sounding rocket data from Punta Chilca, Peru

A technique is described for measuring electron concentrations in the lower portion of the ionosphere above Punta Chilca. A radio-propagation experiment for measuring Faraday rotation is combined with a dc/Langmuir probe experiment for measuring electron current. The results obtained from the analysis of radio and probe data from Nike Apache 14.532, which was launched at 20:26 UT on May 28, 1975, at a solar zenith angle of 60 deg are presented. A comparison of the profiles of electron concentration indicates that the value of the maximum ionization in the D region under quiet conditions is proportional to the square of the cosine of the solar zenith angle.

Fillinger, R. W., Jr.↗
NASA NTRS1977

The multiple applications of electrons in space

An electron source such as a simple cathode is a cheap and light device which can serve several technological and scientific purposes in space: (1) electrostatic charging of a spacecraft can be limited by releasing electrons accumulated on the conductive elements of their surface; (2) the erosion of conductive coatings and the ability of conductive paints to withstand the space environment can be evaluated by monitoring the flow of charged particles impinging on their surface; (3) measuring the current collected by the spacecraft surface as a function of its potential with respect to an emitter is a very sensitive diagnostic technique which can yield a number of plasma parameters, such as density and temperature; (4) it is possible to convert the thermal motion of space plasmas into electrical energy by collecting energetic electrons and returning them to the medium as cold particles; (5) a wave in a plasma is characterized by a conduction current density which gives rise to fluctuations of the current flowing to the surface.

Grard, R. J. L.↗
NASA NTRS1978

Superconducting properties of evaporated copper molybdenum sulfide films

Films of copper molybdenum sulfide were produced by coevaporation. Those that were superconducting contained only the ternary compound and free molybdenum. The range of copper content in the ternary compound was as large as that in polycrystalline material, that is, it includes either phase alone, or a mixture of the two phases of this material. This is in contrast with sputtered materials where copper concentration has been limited to a narrower range. The upper critical field and the critical current were measured as functions of external magnetic field, and found to be similar to those of sputtered copper molybdenum sulfide, when the comparison was made for samples having the same amount of copper.

Woollam, J. A.↗
NASA NTRS1978

Reactively evaporated films of copper molybdenum sulfide

Films of superconducting Chevrel-phase copper molybdenum sulfide CuxMo6S8 were deposited on sapphire substrates by reactive evaporation using H2S as the reacting gas. Two superconducting temperatures (10.0 K and 5.0 K) of the films were found, corresponding to two different phases with different copper concentrations. All films were superconducting above 4.2 K and contained Chevrel-phase compound as well as free molybdenum. The critical current was measured as a function of applied field. One sample was found to deviate from the scaling law found for co-evaporated or sputtered samples, which possibly indicates a different pinning mechanism or inhomogeneity of the sample.

Chi, K. C.↗
NASA NTRS1980

Electron microprobe mineral analysis guide

Electron microprobe mineral analysis guide is a compilation of X-ray tables and spectra recorded from various mineral matrices. Spectra were obtained using electron microprobe, equipped with LiF geared, curved crystal X-ray spectrometers, utilizing typical analytical operating conditions: 15 Kv acceleration potential, 0.02 microampere sample current as measured on a clinopyroxene standard (CP19). Tables and spectra are presented for the majority of elements, fluorine through uranium, occurring in mineral samples from lunar, meteoritic and terrestrial sources. Tables for each element contain relevant analytical information, i.e., analyzing crystal, X-ray peak, background and relative intensity information, X-ray interferences and a section containing notes on the measurement. Originally intended to cover silicates and oxide minerals the tables and spectra have been expanded to cover other mineral phases. Electron microprobe mineral analysis guide is intended as a spectral base to which additional spectra can be added as the analyst encounters new mineral matrices.

Brown, R. W.↗
NASA NTRS1981

Interstellar hot plasma contributions to the diffuse ultraviolet background

The intensity of the diffuse background emission in the far ultraviolet from hot coronal gas present in the plane and halo of the galaxy is calculated. The main emission lines expected are those of C III, IV, N III, IV and Si III, IV at 1909, 1549, 1749, 1487, 1207 and 1398 A respectively. Unless the gas is unusually clumped or has extremely depleted abundances, this source is not of sufficient intensity to influence current broadband measurements of the diffuse continuous ultraviolet background. However, future observations at higher sensitivity and resolution might have to take this effect into account.

Jakobsen, P.↗
NASA NTRS1982

Investigation of cooling properties of the gaseous medium of a space station

An investigation of cooling properties of the gaseous medium was performed in the biosatellite Kosmos-936 as well as in the orbital complexes Soyuz-28/Salyut-6 and Soyuz-30/Salyut-6 with the aid of an especially constructed electric dynamic catathermometer. In this instrument current was measured which was necessary to keep a steady settled temperature of the sensing device. The investigation was performed because of the disturbed heat exhange of the human body caused by lack of natural convection in weightlessness. The instrument also enabled objective estimation of the temperature of the cosmonaut's ody in six optionally selected regions. The results obtained by means of the catathermometer will also enable defining the appropriate hygienic conditions of the gaseous medium of space stations.

Baranski, S.↗
NASA NTRS1983

Interface states and internal photoemission in p-type GaAs metal-oxide-semiconductor surfaces

An interface photodischarge study of p-type GaAs metal-oxide-semiconductor (MOS) structures revealed the presence of deep interface states and shallow donors and acceptors which were previously observed in n-type GaAs MOS through sub-band-gap photoionization transitions. For higher photon energies, internal photoemission was observed, i.e., injection of electrons to the conduction band of the oxide from either the metal (Au) or from the GaAs valence band; the threshold energies were found to be 3.25 and 3.7 + or - 0.1 eV, respectively. The measured photoemission current exhibited a thermal activation energy of about 0.06 eV, which is consistent with a hopping mechanism of electron transport in the oxide.

Kashkarov, P. K.↗
NASA NTRS1983

Spatial relationship of field-aligned currents, electron precipitation, and plasma convection in the auroral oval

Observations reported by Winningham et al. (1975) have established that the auroral oval mapped to the magnetosphere along closed field lines divided the oval into two distinct regions of particle precipitation. In order to determine relationships between field-aligned current, convection, and particle precipitation, simultaneous measurements of all quantities are needed. The studies of Bythrow et al. (1980, 1981) have utilized Atmosphere Explorer C data for sunlit passes of the high-latitude ionosphere. The addition of magnetometer information for the eclipsed high-latitude passes of the Atmospheric Explorer C spacecraft makes it possible to make simultaneous measurements of Birkeland currents, plasma convection, and electron precipitation in the nightside auroral oval and polar cap. The present investigation provides the results of such observations, discusses the observed relationships, and attempts to correlate boundaries.

Coley, W. R.↗
NASA NTRS1985

Eddy-Current Reference Standard

Magnetic properties of metallic reference standards duplicated and stabilized for eddy-current coil measurements over long times. Concept uses precisely machined notched samples of known annealed materials as reference standards.

Ambrose, H. H., Jr.↗
NASA NTRS1983

Model helicopter rotor high-speed impulsive noise: Measured acoustics and blade pressures

A 1/17-scale research model of the AH-1 series helicopter main rotor was tested. Model-rotor acoustic and simultaneous blade pressure data were recorded at high speeds where full-scale helicopter high-speed impulsive noise levels are known to be dominant. Model-rotor measurements of the peak acoustic pressure levels, waveform shapes, and directively patterns are directly compared with full-scale investigations, using an equivalent in-flight technique. Model acoustic data are shown to scale remarkably well in shape and in amplitude with full-scale results. Model rotor-blade pressures are presented for rotor operating conditions both with and without shock-like discontinuities in the radiated acoustic waveform. Acoustically, both model and full-scale measurements support current evidence that above certain high subsonic advancing-tip Mach numbers, local shock waves that exist on the rotor blades ""delocalize'' and radiate to the acoustic far-field.

Boxwell, D. A.↗
NASA NTRS1984

The role of surface generated radicals in catalytic combustion

The role of surface generated OH radicals in determining the catalytic ignition characteristics for propane oxidation on platinum were studied. The experiments were conducted in a stacked-plate, catalyst bed. Transient measurements, during catalytic ignition, of the catalyst's axial temperature profile were made and the effect of equivalence ratio, inlet temperature and inlet velocity was investigated. These measurements will provide insights which will be useful in planning and interpreting to OH measurements. Attempts to measure OH concentration in the catalyst bed using resonance absorption spectroscopy were unsuccessful, indicating that OH concentrations are below 10 to the 16th power/cc but still possibly above equilibrium values. Measurements are currently underway using forward scatter laser induced fluorescence which should extend the OH detection limits several orders of magnitude below the equilibrium concentrations.

Santavicca, D. A.↗
NASA NTRS1984

The rationale and suggested approaches for research geosynchronous satellite measurements for severe storm and mesoscale investigations

The measurements from current and planned geosynchronous satellites provide quantitative estimates of temperature and moisture profiles, surface temperature, wind, cloud properties, and precipitation. A number of significant observation characteristics remain, they include: (1) temperature and moisture profiles in cloudy areas; (2) high vertical profile resolution; (3) definitive precipitation area mapping and precipitation rate estimates on the convective cloud scale; (4) winds from low level cloud motions at night; (5) the determination of convective cloud structure; and (6) high resolution surface temperature determination. Four major new observing capabilities are proposed to overcome these deficiencies: a microwave sounder/imager, a high resolution visible and infrared imager, a high spectral resolution infrared sounder, and a total ozone mapper. It is suggested that the four sensors are flown together and used to support major mesoscale and short range forecasting field experiments.

Shenk, W. E.↗
NASA NTRS1986

Thermal ions at Saturn - Plasma parameters and implications

Plasma data from the PLS experiment on Voyagers 1 and 2 are analyzed at the Saturn encounters. Measured ion currents are simulated using the full response function of the PLS instrument assuming plasma distributions are isotropic Maxwellians. The plasma velocity, densities, and temperatures which best simulate the observations are determined. Saturn's magnetosphere is found to subcorotate outside of L = 5.5 for Voyager 1 and L = 7 for Voyager 2. Large radial and vertical flows are observed, especially in the outer magnetosphere and on the nightside. Ion temperatures increase with L to a maximum at L = 10, outside of which they vary rapidly. A temperature anisotropy with T-perpendicular greater than T-parallel is necessary to account for the observed temperatures and densities. The ions present are H(+) and O(+); there is no evidence of heavier ions or higher charge states. Calculations of N(L-squared) show an O(+) peak at L = 10 for both encounters, indicating the major O(+) source is at L = 10.

Richardson, J. D.↗
NASA NTRS1987

Measuring Conductor Widths and Spacings Electrically

Widths and spacings of conductor lines on integrated circuits measured electrically by split cross-bridge resistor technique. Speeds evaluation of integrated-circuit fabrication processes. When measurement of probe currents and voltages and reduction of measurement data automated, test structure probed and characterized in less than one second.

Buehler, Martin G.↗
NASA NTRS1987

Electro-optical characterization of GaAs solar cells

The electro-optical characterization of gallium arsenide p/n solar cells is discussed. The objective is to identify and understand basic mechanisms which limit the performance of high efficiency gallium arsenide solar cells. The approach involves conducting photoresponse and temperature dependent current-voltage measurements, and interpretation of the data in terms of theory to determine key device parameters. Depth concentration profiles are also utilized in formulating a model to explain device performance.

Olsen, Larry C.↗