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NASA NTRS1975

Cadmium sulfide solar cells

Development, fabrication and applications of CdS solar cells are reviewed in detail. The suitability of CdS cells for large solar panels and microcircuitry, and their low cost, are emphasized. Developments are reviewed by manufacturer-developer. Vapor phase deposition of thin-film solar cells, doping and co-evaporation, sputtering, chemical spray, and sintered layers are reviewed, in addition to spray deposition, monograin layer structures, and silk screening. Formation of junctions by electroplating, evaporation, brushing, CuCl dip, and chemiplating are discussed, along with counterelectrode fabrication, VPD film structures, the Cu2S barrier layer, and various photovoltaic effects (contact photovoltage, light intensity variation, optical enhancement), and various other CdS topics.

Stanley, A. G.↗

NASA NTRS1976

On sound transmission into a stiffened cylindrical shell under flight conditions

In the context of airborne-noise transmission through an aircraft fuselage, a mathematical model is presented for sound transmission into a stiffened cylindrical shell. The stiffening effect of the ring frames and stringers is approximated by a 'smeared'-stiffener theory which includes the eccentricity of the stiffeners. Numerical results are presented for a typical narrow-bodied jet in cruising flight. A comparison is made between noise transmission into a monococque shell and into a stiffened shell. The stiffeners are shown to greatly increase TL for small incidence angles, so that the effective 'window' for noise transmission is restricted to the neighborhood of normal incidence. Flow is shown to increase TL for sound waves propagating 'upstream' against the flow. Stiffeners are also shown to raise the ring frequency at which a dip in cylinder TL occurs. Limitations of the 'smeared'-stiffener theory are also discussed.

Koval, L. R.↗

NASA NTRS1976

ANS observations of Cygnus X-1

Cygnus X-1 was observed from 3 November until 9 November 1974, using the hard X-ray (1-28 keV) and soft X-ray (1-8 keV) experiment on board the Astronomical Netherlands Satellite. On three occasions, on 4 and 5 November, the X-ray spectrum was observed to be harder, while the flux intensity in the 1-7 keV ranges decreased by about 50% from its quiescent value. These events occurred near and following the time of superior conjunction of the likely optical counterpart HDE 226 868. These events appear to be the same as previously reported absorption dips and reveal this phenomenon to be more complex than had been believed. A systematic study of the X-ray spectral variations in these energy bands, on a time scale of 64 seconds over the period of the spectroscopic binary, is presented.

Parsignault, D. R.↗

NASA NTRS1976

Tropical F region winds from O I 1356-A and forbidden OI 6300-A emissions. I - Theory

The paper theoretically investigates the relationship of neutral winds and E x B plasma drifts to the time-dependent distribution of 1356-A and 6300-A airglow intensities in the region of the Appleton anomaly. Radiative recombination, ion-ion neutralization, and dissociative recombination are considered as main mechanisms in producing the atomic oxygen tropical nightglow. A quantitative relation is determined between the neutral wind velocities and the resultant asymmetry in the emissions about the dip equator. The height difference at northern and southern conjugate points is shown to be linearly related to the vector sum of the wind velocity components along the magnetic meridian at the latitude of the conjugate points. The height difference at conjugate points may be used to study the pattern of neutral wind velocities in the tropical ionosphere.

Bittencourt, J. A.↗

NASA NTRS1976

Applicability of ERTS-1 to Montana geology

The author has identified the following significant results. Late autumn imagery provides the advantages of topographic shadow enhancement and low cloud cover. Mapping of rock units was done locally with good results for alluvium, basin fill, volcanics, inclined Paleozoic and Mesozoic beds, and host strata of bentonite beds. Folds, intrusive domes, and even dip directions were mapped where differential erosion was significant. However, mapping was not possible for belt strata, was difficult for granite, and was hindered by conifers compared to grass cover. Expansion of local mapping required geologic control and encountered significant areas unmappable from ERTS imagery. Annotation of lineaments provided much new geologic data. By extrapolating test site comparisons, it is inferred that 27 percent of some 1200 lineaments mapped from western Montana represent unknown faults. The remainder appear to be localized mainly by undiscovered faults and sets of minor faults or joints.

Weidman, R. M.↗

NASA NTRS1977

Analysis of low altitude atmospheric turbulence data measured in flight

All three components of turbulence were measured simultaneously in flight at each wing tip of a Beech D-18 aircraft. The flights were conducted at low altitude, 30.5 - 61.0 meters (100-200 ft.), over water in the presence of wind driven turbulence. Statistical properties of flight measured turbulence were compared with Gaussian and non-Gaussian turbulence models. Spatial characteristics of the turbulence were analyzed using the data from flight perpendicular and parallel to the wind. The probability density distributions of the vertical gusts show distinctly non-Gaussian characteristics. The distributions of the longitudinal and lateral gusts are generally Gaussian. The power spectra compare in the inertial subrange at some points better with the Dryden spectrum, while at other points the von Karman spectrum is a better approximation. In the low frequency range the data show peaks or dips in the power spectral density. The cross between vertical gusts in the direction of the mean wind were compared with a matched non-Gaussian model. The real component of the cross spectrum is in general close to the non-Gaussian model. The imaginary component, however, indicated a larger phase shift between these two gust components than was found in previous research.

Ganzer, V. M.↗

NASA NTRS1976

Uhuru observations of Hercules X-1 during the low state of the 35-day cycle

X-ray emission from Her X-1 has been observed during the 23-day low state of the 35-day cycle. During this time, all the activity normally present during the high state was seen, including regular eclipses, absorption 'dips,' and 1.24-s pulsations. The present observations are compared with the models of Her X-1 derived by Roberts (1974), Gerend and Boynton (1976), Katz (1973), and Petterson (1975). It is suggested that a hot optically thin corona along both faces of the accretion disk can produce the unpulsed component of emission observed during both the high- and low-intensity states.

Jones, C.↗

NASA NTRS1976

Resonant coupling of ionization waves and acoustic gravity waves in the presence of a magnetic field

The nature of the two resonant directions that occur for a single frequency in the presence of a magnetic field is demonstrated, along with the manner in which the resonances change with the dip angle and the angle of propagation from the meridian plane. The conditions under which acoustic branch resonances may occur are outlined. It is found that the calculated frequencies and directions for resonance are in the range of observed values for TID's obtained from ground and satellite measurements. This result is indicative of a possible connection between TID's and the resonance phenomenon. It is shown that a strong resonance type of response may be possible in the F region at a particular frequency from a region that can be as great as 100 km in altitude.

Eun, H.↗

NASA NTRS1976

A study of microseismicity in northern Baja California, Mexico

Five microearthquake instruments were operated for 2 months in 1974 in a small mobile array deployed at various sites near the Agua Blanca and San Miguel faults. An 80-km-long section of the San Miguel fault zone is presently active seismically, producing the vast majority of recorded earthquakes. Very low activity was recorded on the Agua Blanca fault. Events were also located near normal faults forming the eastern edge of the Sierra Juarez suggesting that these faults are active. Hypocenters on the San Miguel fault range in depth from 0 to 20 km although two-thirds are in the upper 10 km. A composite focal mechanism showing a mixture of right-lateral and dip slip, east side up, is similar to a solution obtained for the 1956 San Miguel earthquake which proved consistent with observed surface deformation.

Johnson, T. L.↗

NASA NTRS1977

Impulsive penetration of filamentary plasma elements into the magnetospheres of the earth and Jupiter

Assuming that the solar wind plasma is usually nonuniform over distances of 10,000 km or less, it is shown that filamentary plasma elements stretched out from the sun can penetrate impulsively and become engulfed into the magnetosphere. The diamagnetic effects associated with these plasma inhomogeneities are observed in outer magnetospheres and magnetosheaths as dips or directional discontinuities in the magnetic field measurements. From the mean penetration distances of these diamagnetic plasma elements one can deduce a mean deceleration time, as well as an approximate value of the integrated Pedersen conductivity in the polar cusp of the earth and Jupiter.

Lemaire, J.↗

NASA NTRS1979

Brazing dissimilar aluminum alloys

Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

Dalalian, H.↗

NASA NTRS1978

Noise as a tool for evaluating the activation of cathodes

Measurements, at low frequencies, of the shot noise current from space charge limited cathodes always produced results substantially in excess of theoretical predictions. Measuring the ratio (I sub eq)/S yielded a relation (I sub eq)/S = 1.288 V sub k = 1.288 k(T sub k)/e, independent of the operating point of the diode (triode) as long as all parts of the cathode had a full space charge controlled emission. This method was so sensitive as to permit detection of cathode temperature changes by 1 K, thus it allowed a powerful screening method between well and poorly activated cathodes, superior to dip tests and other current-voltage methods.

Kosmahl, H.↗

NASA NTRS1978

Results of the 1974 through 1977 NASA/JPL balloon flight solar cell calibration program

From 1974 through 1977, seven solar cell calibration flights and two R&D flights with a spectroradiometer as a payload were attempted. There were two R&D flights, and one calibration flight that failed. Each calibration flight balloon was designed to carry its payload to an altitude of 36.6 km (120 kft). The R&D flight balloons were designed for a payload altitude of 47.5 km (150 kft). At the end of the flight period, the upper (solar cell calibration system) and lower (consolidated instrument package (DIP) payloads were separated from the balloon and descend via parachutes. The calibrated solar cells recovered in this manner were used as primary intensity reference standards during solar simulator testing of solar cells and solar arrays with similar spectral response characteristics. This method of calibration has become the most widely accepted technique for developing space standard solar cells.

Sidwell, L. B.↗

NASA NTRS1978

Compatibility Studies of Various Refractory Materials in Contact with Molten Silicon

The production of low cost, efficient solar cells for terrestrial electric power generation involves the manipulation of molten silicon with a present need for noncontaminating, high temperature refractories to be used as containment vessels, ribbon-production dies, and dip-coated substrates. Studies were conducted on the wetting behavior and chemical/physical interactions between molten silicon and various refractory materials.

Odonnell, T.↗

NASA NTRS1978

Diode laser saturation spectroscopy of NH3

Saturation of molecular transitions using a tuneable diode laser was demonstrated for the first time using a standing-wave cavity configuration with an f/8 beam focussed at the sample. Observed saturation effects in NH3 transitions near 888/cm include sub-Doppler (Lamb-dip) resonances at line center.

Jennings, D. E.↗

NASA NTRS1977

Mathematical and computational studies of equilibrium capillary free surfaces

The results of several independent studies are presented. The general question is considered of whether a wetting liquid always rises higher in a small capillary tube than in a larger one, when both are dipped vertically into an infinite reservoir. An analytical investigation is initiated to determine the qualitative behavior of the family of solutions of the equilibrium capillary free-surface equation that correspond to rotationally symmetric pendent liquid drops and the relationship of these solutions to the singular solution, which corresponds to an infinite spike of liquid extending downward to infinity. The block successive overrelaxation-Newton method and the generalized conjugate gradient method are investigated for solving the capillary equation on a uniform square mesh in a square domain, including the case for which the solution is unbounded at the corners. Capillary surfaces are calculated on the ellipse, on a circle with reentrant notches, and on other irregularly shaped domains using JASON, a general purpose program for solving nonlinear elliptic equations on a nonuniform quadrilaterial mesh. Analytical estimates for the nonexistence of solutions of the equilibrium capillary free-surface equation on the ellipse in zero gravity are evaluated.

Albright, N.↗

NASA NTRS1978

A study of the structural-acoustic response and interior noise levels of fuselage structures

Models of both flat and curved fuselage panels were tested for their sound transmission characteristics. The effect of external air flow on transmission loss was simulated in a subsonic wind-tunnel. By numerically evaluating the known equations for field-incidence transmission loss of single-walled panels in a computer program, a comparison of the theory with the test results was made. As a further extension to aircraft fuselage simulation, equations for the field-incidence transmission loss of a double-walled panel were derived. Flow is shown to provide a small increase in transmission loss for a flat panel. Curvature is shown to increase transmission loss for low frequencies, while also providing a sharp decrease in transmission loss at the ring frequency of the cylindrical panel. The field-incidence transmission loss of a double-walled panel was found to be approximately twice that for a single-walled panel, with the addition of dips in the transmission loss at the air gap resonances and at the critical frequency of the internal panel.

Koval, L. R.↗

NASA NTRS1977

Chemical and petrographic constraints on the origin of chondrules and inclusions in carbonaceous chondrites

Bulk chemical compositions of the various petrographic types of chondrules and inclusions in Type 3 carbonaceous chondrites (excluding those affected by metamorphism) have been determined by microprobe defocused-beam analysis. Inclusion compositions follow approximately the theoretical compositional trajectory for equlibrium condensation. Chondrules occurring in the same meteorites have higher silica contents and show only slight overlap with inclusion compositions. Dust fusion is apparently an inadequate mechanism for producing the wide chemical variations observed among chondrules. Impact-melting models require sampling of complex target rocks which are unknown as components of meteorites; this mechanism also demands efficient mechanical processing of chondrules before accretion. A genetic relationship between chondrules and inclusions in carbonaceous chondrites is suggested by the compositional continuum between these objects. A condensation sequence which dips into the liquid stability field at lower temperatures is advocated for the production of both inclusions and chondrules. Textural relationships between intergrown chondrules and inclusions support such a sequence. This model suggests that the assembled components (inclusions and chondrules) of carbonaceous chondrites are related by a common process.

Mcsween, H. Y., Jr.↗