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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Solar cell with improved N-region contact and method of forming the same

An improved solar cell, and method of forming the same are disclosed. It is characterized by a semiconductor silicon wafer of P-type material having diffused therein a shallow N-type region. A sintered silver contact is affixed to the surface of the N-type region at the outer surface. The improved solar cell is formulated from silver powder blended with silver metaphosphate for establishing a zone of increased carrier concentration. An aluminum or silver-aluminum alloy contact is affixed to the P-type wafer at the outer surface opposite the N-type region.

Bube, K. R.↗
NASA NTRS1979

Microscale instabilities in stream interaction regions

The microstructure of solar wind stream interaction regions is considered theoretically with emphasis on the role of several electrostatic kinetic instabilities which may be important within the stream interface and the compression region. Inside of 1 AU, the interface is likely to be stable against the electrostatic streaming instabilities considered. Between 1 and 2 AU, the interface will excite the magnetized ion-ion instability. The compression region is also found to be unstable beyond 1 AU where the modified two-stream instability, beam-cyclotron instability, and ion-acoustic instability are important in determining the structure of the compressive pulses as they evolve into forward and reverse shocks. It is concluded that the modified two-stream instability and beam-cyclotron instability predominately play a role in heating the electrons to the threshold for the ion-acoustic instability. Various electrostatic plasma waves, ranging in frequency from the lower-hybrid to harmonics of the electron cyclotron frequency, would be produced by these instabilities. Their signature should also be seen by high time resolution measurements of the temperature of the various plasma species.

Eviatar, A.↗
NASA NTRS1978

A computational scheme usable for calculating the plume backflow region

The effects of the nozzle wall boundary layer on the plume flowfield are neglected in the majority of computational schemes which exist for the calculation of rocket engine exhaust plume flowfields. This neglect, which is unimportant in many applications, becomes unacceptable for applications where a surface which can be adversely affected by plume impingement forces, heating, or contamination is located behind the nozzle exit plane in what is called the 'plume backflow region'. The flow in this region originates in, and is highly affected by, the nozzle wall boundary layer. The inclusion of the effects of the boundary layer in the calculations is required for an appropriate determination of the flowfield properties within this region. A description is presented of the results of modifications of a method-of-characteristics computer program. The modifications were made to include the effects of the nozzle wall boundary layer on the plume flowfield. A comparison of computed and experimental data indicates that the employed computer program may be a useful tool for calculating the entire plume flowfield for liquid propellant rocket engines.

Cooper, B. P., Jr.↗
NASA NTRS1979

The coronal atmosphere above solar active regions - Comparison of high spatial resolution soft X-ray and centimetric observations

High spatial resolution observations of solar active regions in soft X-rays and centimetric wavelengths are compared using X-ray and radio data obtained during the 1973 Skylab mission. An overall correspondence in position and size between regions of enhanced X-ray emission and regions of enhanced microwave emission was noticed. However, a closer analysis of the findings suggested that substantial differences exist between the emission properties of the atmosphere over sunspots and that over plages, with the difference probably related to the average intensity of the magnetic field, which was found to be higher over sunspot umbrae than over plage areas.

Pallavicini, R.↗
NASA NTRS1978

From Serenity to Langemak - A regional chemical setting for Mare Crisium

The chemistry of the region surrounding Mare Crisium is described using improved Al/Si and Mg/Si intensity ratios derived from Apollo 15 X-ray fluorescence measurements. Mg/Si ratios are shown to increase from 0.6 in the region east of Mare Smythii to 1.0 in western Mare Serenitatis, while Al/Si ratios show sharp decreases in all mare areas. It is concluded that the terra (nonmare) material has a uniform Al/Si ratio, hence plagioclase content, and increases in the Mg/Si ratio in terra material imply similar increases of Mg in the pyroxenes and olivines of this material. The observed diversity of terra soils can be explained by an originally chemically diverse region not homogenized by heavy bombardment, or by volcanism subsequent to bombardment. Maria Crisium, Serenitatis and Smythii are found to be filled with low albedo materials which have a wide range of Mg/Si values, with small and apparently consistent differences in Al/Si ratio.

Hubbard, N. J.↗
NASA NTRS1978

Correlation of chemistry with normal albedo in the Crisium region

The region in the vicinity of the Luna 24 handling site (40-70 deg E; 0-20 deg N) is studied by means of the Apollo orbital fluorescent X-ray Al/Si and Mg/Al data and earth-based normal albedo measurements. By means of unsupervised non-parametric cluster analysis this region is divided into eight surface units. One of these units centered in the Proclus region deviates from the usual trend of increasing normal albedo with increasing Al/Si values and decreasing Mg/Al values

Bielefeld, M. J.↗
NASA NTRS1979

Compact H II regions in the far-infrared

Far-infrared (40-150 microns) observations of W51 (G49.5-0.4), K3-50, DR 21, NGC 7538, and W3(OH) are presented and discussed. At these wavelengths each source is dominated by a small bright component closely associated with a compact H II region. Their spectra can be explained as emission by dust at temperatures of 30-50 K. Some of the objects appear to be optically thick out to wavelengths of about 60 microns. Of the 10 source components in the five regions, at least four may be powered by pre-main-sequence stars. The far-infrared data are consistent with depletion of volatile components of the dust within compact H II regions, but do not clearly require destruction or expulsion of refractory grains. The bulk of the dust which emits primarily in the far-infrared must lie in a dense shell immediately outside the ionized zone. The sources are possible precursers to open clusters with stellar masses in the range from 1,000 to 10,000 solar masses.

Thronson, H. A., Jr.↗
NASA NTRS1979

X-ray emission from the region of gamma 195+5

In the present study, the region of the gamma 195 + 5 was searched for X-ray emission to a level of approximately 10 to the minus eleventh erg/sq cm-sec. A source is detected whose position is in agreement with the position of the gamma-ray source. The area of the X-ray box is approximately five times smaller than the estimated gamma-ray error region; it will guide further observations at X-ray and other wavelengths. The probability that the source is located by chance within the gamma-ray error region is estimated at 9%. The X-ray spectrum appears to be too steep to extrapolate simply toward the 100 MeV point.

Lamb, R. C.↗
NASA NTRS1979

The upper mantle transition region - Eclogite

The upper mantle transition region is usually considered to be peridotite which undergoes a series of phase changes involving spinel and post-spinel assemblages. There are difficulties associated with attempts to explain the 220, 400 and 670 km discontinuities in terms of phase changes in a peridotitic mantle. Moreover, in a differentiated earth there should be large quantities of eclogite in the upper mantle. Eclogite is denser than Al2O3-poor mantle to depths of 670 km, but it stays in the garnet stability field to pressures in excess of those required to transform depleted mantle to denser phases such as ilmenite and perovskite. Eclogite, therefore, remains above 670 km. The seismic properties of the transition region are more consistent with eclogite than peridotite. Most of the mantle's inventory of incompatible trace elements may be in this layer, which is a potential source region for some basalt magmas. The radioactivity in this layer is the main source of mantle heat flow, 0.7 microcalorie/sq cm-sec, and drives upper mantle convection.

Anderson, D. L.↗
NASA NTRS1979

Morphology and phenomenology of the high-latitude E and F regions

Results obtained at high latitude observatories on the behavior of E and F region ionization are presented including a bibliography. Behavior of E and F region ionization during day and night for quiet and disturbed conditions in the auroral and polar regions is described. Daily, seasonal and sunspot variations are also outlined.

Hunsucker, R. D.↗
NASA NTRS1979

Report of the mid- and low-latitude E and F Region Working Group

The formation and variation of the ionosphere is addressed with regard to the ability to understand, specify, and predict the low and mid latitude E and F regions. A brief survey of prediction methods and techniques is given for long and short term variability in the E and F regions. It is indicated that the usefulness of theoretical models to predict electron density distribution in the low and mid latitude ionospheric E and F regions is limited by the ability to predict the parameters which enter the relevant equations; i.e., neutral atmospheric constituents, neutral and charged particle temperatures, neutral wind, electric fields, and ionizing sources such as solar (E sub uv) radiation and energetic particles. It is recommended that areas for research include improving knowledge of the input parameters and how they respond to changing solar and geophysical conditions.

Rush, C. M.↗
NASA NTRS1979

Lunar libration region L4 photometry

Photometry of the lunar libration region L4 obtained in double umbra during the lunar orbital flight of Apollo 15 is reported. A four-minute photographic exposure of the region centered at celestial coordinates 23 h 14 m, -1.8 deg was made using a 35-mm camera at f/1.2 in the command module pilot's window. The film had been calibrated to the sun's surface brightness, and scene brightness information was converted to digital form, followed by high-speed digital processing with vignetting removal to obtain absolute photometric values. Results reveal an elliptical brightness region 16 x 12 deg in extent with an absolute brightness of 3.3 x 10 to the -14th sun surface brightness units. The mass of the scattering material responsible for the effect is estimated to be between 6 x 10 to the 18th and 2 x 10 to the 7th g.

Mercer, R. D.↗
NASA NTRS1980

On the formation of nonlinear internal waves from the gravitational collapse of mixed regions in two and three dimensions

The paper shows how trains of nonlinear, dispersive waves can be produced by allowing a region of mixed fluid, with a potential energy greater than its surroundings, to collapse towards its equilibrium state. The number of waves and their amplitude depend on the properties of the mixed region and of the ambient stratification. Three different geometrical configurations have been chosen and while each gives qualitatively the same results the form taken by the generated waves and the final equilibrium shape of the mixed region depend critically on these geometrical factors. The internal waves produced by this mechanism are related to waves produced in natural systems and it is shown that the observations support at least one possible explanation for those found in the oceans and planetary atmospheres.

Maxworthy, T.↗
NASA NTRS1979

Regional chemical variations in lunar basaltic lavas

The higher Al2O3 concentrations in mare soils at Apollo landing sites, relative to mare basalts, have generally been attributed to the presence of 20-30% of terra material in the mare surface regolith. This viewpoint is shown to be erroneous when entire maria are studied; the amount of terra material in typical mare surface regoliths is only about 5%, or less. The bulk of the mare soils are the comminuted remains of aluminous mare basalt flows. On a regional scale, the sample and orbital data for maria define prominent chemical variations that are well beyond those expected from simple igneous processes and therefore indicate that gradations in one or more of the major parameters of planetary differentiation caused these variations. The increasingly abundant evidence for regional variations in the chemical compositions of lunar basalts requires that regional petrogenetic provinces must be considered in models of lunar evolution.

Hubbard, N.↗
NASA NTRS1980

Spectrophotometry of H II regions and the nucleus of NGC 1566

The paper presents spectrophotometric observations of the nucleus and nine H II regions in the spiral arms of the Sbc galaxy NGC 1566. The emission line spectra of the H II regions are characterized by a low grade of ionization, and most of the line intensities do not show radial gradients; the N II/O II forbidden line ratio appears to increase toward the nucleus, and the forbidden O III/H-beta ratio may decrease in the same direction. This is explained by the increase of the oxygen abundance and decrease of the electron temperature toward the nucleus; the spectra confirm the presence of the weak, broad emission wings at H-alpha, and the nuclear spectrum of NGC 1566 resembles that of a giant H II region rather than that of a Seyfert galaxy.

Hawley, S. A.↗
NASA NTRS1980

Microscale instabilities in stream interaction regions

A theoretical investigation of the microstructure of solar wind stream interaction regions is presented. The role of several electrostatic kinetic instabilities is discussed which may be important within the stream interface and the compression region. Inside of 1 AU the interface is likely to be stable against the electrostatic streaming instabilities considered. Between 1 and 2 AU it is argued that the interface will excite the magnetized ion-ion instability. The compression region is also found to be unstable beyond 1 AU, where the modified two-stream instability, beam-cyclotron instability, and ion-acoustic instability will be important in determining the structure of the compressive pulses as they evolve into forward and reverse shocks. It is concluded that the modified two-stream instability and beam-cyclotron instability predominately play a role in heating the electrons to the threshold for the ion-acoustic instability.

Eviatar, A.↗
NASA NTRS1980

Temporal variations in regional models of the Sargasso Sea from GEOS-3 altimetry

The paper considers temporal variations in regional models of the Sargasso sea from GEOS-3 telemetry. The methods of regional models and the analysis of overlapping passes are utilized, and short-wave maxima and minima in the regional surface models are examined for correlations with surface and remote sensed infrared temperature data supplemented with subsurface expendable bathythermograph data (XBT). The analysis of overlapping passes provide a better picture of instanteneous sea surface height (SSH) variability through wavelengths greater than 30 km. Correlation studies with cyclonic and anticyclonic ocean eddies from infrared imagery and XBT data indicate satisfactory agreement with equivalent SSH features 98% of the time if the time varying factors are allowed for.

Mather, R. S.↗
NASA NTRS1980

High-latitude ion convection in the nighttime F region

A large data base of Atmosphere Explorer C measurements of the bulk ion velocity vector in the high-latitude F region has been examined. The concept of shear and rotational flow reversals is expanded upon to determine the extent to which the boundary between antisunward and sunward convection (i.e., a polar cap boundary) is an electrostatic equipotential. A most important factor in characterizing the nature of the large-scale geometrical configuration of the nighttime F region convection is the location and extent of quasi-equipotential regions of the convection reversal boundary.

Heelis, R. A.↗