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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A reliable all-silver front contact for silicon solar cells

The feasibility of making an adherent and moisture degradation resistant silver-only front contact to silicon solar cells was demonstrated. Optimum fabrication processes and process sequences were determined for making such contacts. These contacts were found to also have good electrical characteristics. A back contact of aluminum-silver was also developed. This proved very satisfactory for low-temperature applications.

Lamneck, J. H., Jr.↗
NASA NTRS1972

Wave-front singularities for two-dimensional anisotropic elastic waves.

Wavefront singularities for the displacement functions, associated with the radiation of linear elastic waves from a point source embedded in a finitely strained two-dimensional elastic solid, are examined in detail. It is found that generally the singularities are of order d to the -1/2 power, where d measures distance away from the front. However, in certain exceptional cases singularities of order d to the -n power, where n = 1/4, 2/3, 3/4, may be encountered.

Payton, R. G.↗
NASA NTRS1973

Variation of the low level winds during the passage of a thunderstorm gust front

Three time histories of wind profiles in thunderstorm gust fronts at Cape Kennedy and three at Oklahoma City are analyzed. Wind profiles at maximum wind strength below 100 m follow logarithmic laws, so that winds above the surface layer can be estimated from surface winds once the roughness length is known. A statistical analysis of 81 cases of surface winds during thunderstorms at Tampa revealed no predictor with skill to predict the time of maximum gust. Some 34% of the variance of the strength of the gust is accounted for by a stability index and surface wind prior to the gust; the regression equations for these variables are given. The coherence between microscale wind speed variations at the different levels has the same proportions as in non-thunderstorm cases.

Sinclair, R. W.↗
NASA NTRS1972

A reliable all-silver front contact for silicon solar cells.

Methods have been found to apply an adherent and humidity resistant silver-only front contact to n on p silicon solar cells. The critical processing step was the removal of the diffused oxide layer. Humidity resistance is superior to present day commercial titanium-silver contacts and the electrical characteristics of the cells are excellent. Titanium, which is degraded by humidity and which is a source of heavy metal poisoning, has been eliminated from the contact.

Lamneck, J. H., Jr.↗
NASA NTRS1972

Toward assessing the effects of crack front curvature /CFC/.

Consideration of the effect of crack front curvature (CFC) on the K calibration of five special geometries in which CFC occurs. The five cases considered include an elliptical crack in an infinite medium, an internal annular crack in a thick-walled cylinder, a through crack in a flat plate, a part-through crack in a plate, and an irregularly shaped crack in a solid. It is shown that K depends on CFC differently in each case.

Swedlow, J. L.↗
NASA NTRS1973

User's manual for the TRW gaspipe 2 program: A vapor-gas front analysis program for heat pipes containing non-condensible gas

A digital computer program for design and analysis of heat pipes which contain non-condensible gases, either for temperature control or to aid in start-up from the frozen state, is presented. Some of the calculations which are possible with the program are: (1) wall temperature profile along a gas-loaded heat pipe, (2) amount of gas loading necessary to obtain desired evaporator temperature at a desired heat load, (3) heat load versus evaporator temperature for a fixed amount of gas in the pipe, and (4) heat and mass transfer along the pipe, including the vapor-gas front region.

Edwards, D. K.↗
NASA NTRS1974

Shapes of strong shock fronts in an inhomogeneous solar wind

The shapes expected for solar-flare-produced strong shock fronts in the solar wind have been calculated, large-scale variations in the ambient medium being taken into account. It has been shown that for reasonable ambient solar wind conditions the mean and the standard deviation of the east-west shock normal angle are in agreement with experimental observations including shocks of all strengths. The results further suggest that near a high-speed stream it is difficult to distinguish between corotating shocks and flare-associated shocks on the basis of the shock normal alone. Although the calculated shapes are outside the range of validity of the linear approximation, these results indicate that the variations in the ambient solar wind may account for large deviations of shock normals from the radial direction.

Heinemann, M. A.↗
NASA NTRS1974

Wideband infrared heterodyne receiver front-end

A 10.6 micron infrared heterodyne receiver front end was developed for use in a wideband CO2 laser communications link. The infrared receiver employs an 850 MHz response PV HgCdTe photomixer which is mounted in a space quality housing, a low-noise 5 to 1500 MHz IF preamplifier, and a remote control panel. The receiver was designed to handle + or - 750 MHz of Doppler shift while providing an instantaneous information bandwidth of 400 MHz. The measured receiver sensitivity NEP was 1.0 x 10 to the 19th power W/Hz for a photomixer temperature of T sub m = 77 K and an IF beat frequency of 20 MHz and degraded to 1.75 x 10 to the 19th power W/Hz for T sub m = 130 K.

Peyton, B. J.↗