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Results for “ULTRAVIOLET RADIATION”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

The degradation of alzak by short wavelength ultraviolet radiation

The changes in reflectance of thermal aluminum coating samples exposed to different irradiating utraviolet wavelengths are discussed. It is shown that the coating is damaged faster and further by 180 to 210 in radiation than by Lyman alpha radiation. On an equivalent incident energy basis, Lyman alpha does less damage than 180 to 210 nm radiation. Above 300 nm no degradation is observed for long exposures and below 300 nm increasing degradation with decreasing wavelength is found. It is concluded that Lyman alpha radiation need not be included in laboratory testing of this thermal coating for spacecraft structures.

Donohoe, M. J.↗
NASA NTRS1972

Monitoring of solar far ultraviolet radiation from the OSO-5 satellite

A spectrophotometer for monitoring the solar EUV in three broad wavelength bands is described. The kind of data obtained, along with sources of error, are presented. The content of the tape library which contains the data is outlined. The scientific results are discussed. These include the following: solar flares in the EUV, solar eclipse observations in the EUV, SFD's and relationship to solar flares, and the application of satellite sunrise and sunset data for the study of model upper atmospheres for the earth.

Rense, W. A.↗
NASA NTRS1972

Electron spin resonance of ultraviolet radiation induced defects in ZnO thermal control coating pigment.

Electron spin resonance measurements on variously treated zinc oxide powders reveal that the resonance signal at g = 1.956 is due to one electron trapped oxygen ion vacancy level, at a depth of (0.31 plus or minus 0.02) eV below the conduction band. The electrons at this level are delocalized. Schottky barrier influences nearly the entire bulk of the powder sample, and the bending of the bands caused by chemisorbed oxygen puts the vacancy level above the Fermi level almost through the entire bulk.

Mookherji, T.↗
NASA NTRS1972

Development of programs for computing characteristics of ultraviolet radiation

Efficient programs were developed for computing all four characteristics of the radiation scattered by a plane-parallel, turbid, terrestrial atmospheric model. They were developed (FORTRAN 4) and tested on the IBM /360 computers with 2314 direct access storage facility. The storage requirement varies between 200K and 750K bytes depending upon the task. The scattering phase matrix (or function) is expanded in a Fourier series whose number of terms depend upon the zenith angles of the incident and scattered radiations, as well as on the nature of aerosols. A Gauss-Seidel procedure is used for obtaining the numerical solution of the transfer equation.

Dave, J. V.↗
NASA NTRS1975

Search for extreme ultraviolet radiation from selected stars

Results are reported for a search for EUV radiation between 140 and 430 A from selected objects which was conducted with a rocket-borne EUV filter photometer. The candidate objects included the bright planetary nebula NGC 2392 and the stars gamma Gem, alpha CMa, omicron-prime CMa, and gamma-2 Vel. Upper limits (2-sigma level) to the flux near 200 A are determined for the five objects, and estimates of the expected 200-A helium-continuum flux are derived for two of the stars on the basis of the hot-corona model. It is found that the calculated upper limits are at least two orders of magnitude higher than plausible flux estimates based on the hot-corona model. However, it is noted that uncertainties in the flux estimates are great enough to make the upper limits useful.

Riegler, G. R.↗
NASA NTRS1976

Assessment of the impact of increased solar ultraviolet radiation upon marine ecosystems

Data was provided to assess the potential impact upon marine ecosystems if space shuttle operations contribute to a reduction of the stratospheric ozone layer. The potential for irreversible damage to the productivity, structure and/or functioning of a model estuarine ecosystem by increased UV-B radiation was established. The sensitivity of key community components (the primary producers) to increased UV-B radiation was delineated.

Vandyke, H.↗
NASA NTRS1977

Assessment of the impact of increased solar ultraviolet radiation upon marine ecosystems

Specifically, the study has addressed the following: (1) potential for irreversible damage to the productivity, structure and/or functioning of a model estuarine ecosystem by increased UV-B radiation or ecosystems highly stable or amenable to adaptive change, and (2) the sensitivity of key community components (the primary producers, consumers, and decomposers) to increased UV-B radiation. Three areas of study were examined during the past year: (1) a continuation of the study utilizing the two seminatural ecosystem chambers, (2) a pilot study utilizing three flow-through ecosystem tanks enclosed in a small, outdoor greenhouse, and (3) sensitivity studies of representative primary producers and consumers.

Vandyke, H.↗
NASA NTRS1978

Upper limits on extreme ultraviolet radiation from nearby main sequence and subgiant stars

Flux upper limits for 44-800 A radiation were measured in a sample of nearby main sequence stars and one subgiant star with the aid of the Apollo-Soyuz grazing incidence telescope. Comparisons of emission measure upper limits with three different methods for predicting coronal properties cannot yet determine which, if any, are valid. Data for Alpha Centauri A and B are consistent with recent HEAO-1 soft X-ray measurements which suggest that the surface flux of coronal emission from the Alpha Cen system is comparable to that of the 'normal' sun.

Ayres, T. R.↗
NASA NTRS1981

The variability of the sun's ultraviolet radiation

Solar UV intensity variations determined by direct irradiance measurements and by measurements of the plage/quiet sun contrast are reviewed. Typical values for the solar UV variability over a solar cycle are: less than 1% at wavelengths longer than 2100 A, 8% at 2080 A (continuum), 20% at 1900 A (continuum), 70% at H Ly alpha, 200% in certain emission lines in the 1200-1800 A range, and more than a factor of 4 in coronal lines at less than 1000 A.

Brueckner, G. E.↗