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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Optical properties of ion beam textured metals

Copper, silicon, aluminum, titanium and 316 stainless steel were textured by 1000 eV xenon ions from an 8-cm diameter electron bombardment ion source. Copper, silicon, and aluminum developed a cone structure with an average peak-to-peak distance ranging from 1 micron for silicon to 6 microns for aluminum. Titanium and 316 stainless steel developed a serpentine ridge structure. The average peak-to-peak distance for both of these materials was 0.5 micron. Total reflectance for air mass 0 and 2, solar absorptance, and total emittance, normalized for a 425 K black body were calculated from the reflectance measurements. All materials had solar absorptances between 0.93 (stainless steel) and 0.97 (silicon and aluminum). Total emittance values of 0.75, 0.80, and 0.85 for Si, Al, and Cu, respectively, resulted in a solar absorptance/total emittance ratio of approximately 1.2. Titanium and 316 stainless steel had values of 2.6 and 2.9, respectively, for this ratio.

Hudson, W. R.↗
NASA NTRS1976

The surface chemical composition of lunar samples and its significance for optical properties

The surface Fe, Ti, Ca, and Si concentrations in a variety of soil and rock samples from all the Apollo sites are determined using an Auger spectrometer plus a single-pass cylindrical-mirror analyzer with a standard 15-stage BeCu electron multiplier. It is found that there are no great differences between the surface and bulk concentrations of any of the four elements in the rock samples, but the surface Fe and Ti concentrations in soil samples are higher than the bulk concentrations. Results are also reported for solar-wind simulation experiments in which a pulverized rock sample was bombarded with 2-keV alpha-particles corresponding to about a 30,000-yr dose of the solar-wind proton component. These results indicate that the chemical change induced on the surface of a rock powder by positive-ion bombardment is similar to the change from bulk to surface chemical composition in lunar soil samples. A clear correlation is observed between the surface Fe concentration and albedo of the soil samples.

Gold, T.↗
NASA NTRS1977

Measurement of the optical properties of lunar rocks in the transition zone, resulting from observations made by Lunokhod 2

Photometric measurements were carried out directly on the lunar surface with the aid of a calibration device, a plate with fields of different brightness, placed in the field of view of the panoramic telephotometers. The brightness of the fields of the calibration plate were measured in preliminary studies, relative to the brightness of a magnesia screen. This permitted determination of the reflectance features of the surficial lunar material relative to the standard most widely used in brightness studies of natural substances. The total brightness of sections a few centimeters across was recorded in direct proximity to the apparatus. The total area investigated in one panorama was about one square meter. Several areas in the mare and highland regions were studied. The albedos of various surface objects were obtained. A comparison of the brightness measurements with data from the RIFMA-M instrument discloses a correlation of the albedo change with change in chemical composition of the surface rock. Direct photometric studies of the lunar surface in the "mare-highland" transition zone assist in tracing the transition from one type of rock to another, and in obtaining information on the processes of material exchange between these two types of lunar landscape.

Lipskiy, Y. N.↗
NASA NTRS1978

Optical properties of silicates in the far ultraviolet

Near-normal incidence reflectance measurements in the interval 1026-1640 A were performed on four silicates already studied in the visible and infrared. A Kramers-Kronig analysis of these data is used to calculate the complex index of refraction m = n - ik. New transmission measurements improve the determination of k in the interval 2500-4500 A, except for andesite, which is more opaque than had been previously observed.

Lamy, P. L.↗
NASA NTRS1980

X-ray optical properties of a Wolter telescope

Physical properties and the fabrication sequence of a Wolter telescope are discussed. Such telescopes are intended to examine the dust scattering halos after being placed in orbit by a booster rocket launched from Australia.

Ondrusch, A.↗
NASA NTRS1979

Optical properties of solid CO2 - Application to Mars

Using a special low-temperature cell, thick layers of solid CO2 are grown on an infrared-transparent window. The transmission spectra of solid CO2 is measured from 4000 to 360 kaysers (2.5-27.8 microns). The complex index of refraction is derived for samples of different thicknesses. Scattering in the samples is the major source of error. Away from the major absorption bands the imaginary index is very low. The absorption coefficient is of the order of 1 kayser. The emissivity in the Viking IRTM 20-micron band of a solid surface of CO2 is estimated at 0.72 + 0.17 or -0.10. Snowlike deposits have similar or lower emissivity. The results of this paper relieve the need for exceptional meteorology to explain Martian brightness temperatures below the CO2 frost point.

Ditteon, R.↗
NASA NTRS1980

Lunar magnetic anomalies and surface optical properties

Consideration is given to the influence of lunar magnetic anomalies on the darkening of the lunar surface by solar wind ion bombardment. It is shown that lunar magnetic anomalies with dipole moments much greater than 5 x 10 to the 13th gauss cu cm will strongly deflect the typical solar wind, producing local plasma voids at the lunar surface. Direct measurements of lunar magnetic fields have shown most lunar magnetic fields to have moments below this level, with the exception of anomalies detected in the areas of the Reiner Gamma albedo feature, the Van de Graaff-Aitken region and Mare Marginis. Such magnetic anomalies are shown to be capable of accounting for the higher albedo and swirl-like morphology f these features by the deflection and focusing incident solar wind ions, which tend to darken the surface upon impact.

Hood, L. L.↗
NASA NTRS1985

Optical properties of solid and liquid sulfur at visible and infrared wavelengths

The real part of the refractive index of liquid sulfur and solid orthorhombic sulfur was measured in the 0.4-2.0 micron range, with reference to applications to Venus, Jupiter, Amalthea, Io, and the earth. The imaginary part of the refractive index of liquid sulfur was also measured, and the reflectance of semiinfinite slabs of solid and liquid sulfur was calculated on the basis of the measured values of the real and imaginary parts of the refractive index. The conclusion that liquid sulfur melts on Io would be classified as 'black' by the Voyager spectrophotometric analysis is confirmed.

Sasson, R.↗
NASA NTRS1987

Boron nitride: Composition, optical properties and mechanical behavior

A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at %. The carbon and oxygen impurities were in the 5 to 8 at % range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

Pouch, John J.↗
NASA NTRS1988

Optical properties of Southern Hemisphere aerosols: Report of the joint CSIRO/NASA study

This study was made in support of the LAWS and GLOBE programs, which aim to design a suitable Doppler lidar system for measuring global winds from a satellite. Observations were taken from 5 deg S to 45 deg S along and off the E and SE Australian coast, thus obtaining representative samples over a large latitude range. Observations were made between 0 and 6 km altitude of aerosol physical and chemical properties in situ from the CSIRO F-27 aircraft; of lidar backscatter coefficients at 10.6 micron wavelength from the F-27 aircraft; of lidar backscatter profiles at 0.694 microns at Sale, SE Australia; and of lidar backscatter profiles at 0.532 microns at Cowley Beach, NE Australia. Both calculations and observations in the free troposphere gave a backscatter coefficient of 1-2 x 10 to the -11/m/sr at 10.6 microns, although the accuracies of the instruments were marginal at this level. Equivalent figures were 2-8 x 10 to the -9/m/sr (aerosol) and 9 x 10 to the -9 to 2 x 10 to the -8/m/sr (lidar) at 0.694 microns wavelength at Sale; and 3.7 x 10 to the -9/m/sr (aerosol) and 10 to the -8 to 10 to the -7/m/sr (lidar) at 0.532 microns wavelength at Cowley Beach. The measured backscatter coefficients at 0.694 and 0.532 microns were consistently higher than the values calculated from aerosol size distributions by factors of typically 2 to 10.

Gras, John L.↗
NASA NTRS1987

Boron nitride - Composition, optical properties, and mechanical behavior

A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at. percent. The carbon and oxygen impurities were in the 5 to 8 at. percent range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

Pouch, John J.↗
NASA NTRS1989

Optical properties of sputtered aluminum on graphite/epoxy composite material

Solar absorptance, emittance, and coating thickness were measured for a range of coating thicknesses from about 400 A to 2500 A. The coatings were sputtered from an aluminum target onto 1-inch-diameter substrates of T300/5209 graphite/epoxy composite material with two different surface textures. Solar absorptance and emittance values for the specimens with the smooth surface finish were lower than those for the specimens with the rough surface finish. The ratio of solar absorptance to emittance was higher for the smooth specimens, increasing from 2 to 4 over the coating thickness range, than for the rough ones, which had a constant ratio of about 1. The solar absorptance and emittance values were dependent on the thickness of the sputtered coating.

Witte, William G., Jr.↗
NASA NTRS1988

Some optical properties of KTP, LiIO3, and LiNbO3

Measurements of the absorption coefficient for KTP, LiIO3, and LiNbO3 are discussed. The variation of the refractive index with temperature has been measured for KTP and LiIO3. It is necessary to know both the absorption coefficient beta and the variation in the indexes of refraction with temperature change dn/dT to determine the average power limit of a nonlinear interaction. With the dn/dT information, it is also possible to estimate the temperature half width of any nonlinear interaction by calculating the variation of the phase-matching condition with temperature.

Gettemy, Donald J.↗
NASA NTRS1989

Solar radiative transfer in cirrus clouds. I - Single-scattering and optical properties of hexagonal ice crystals. II - Theory and computations of multiple scattering in an anisotropic medium

The light scattering and absorption programs of Cai and Liou (1982) and Takano and Jaweera (1985) are extended to include hexagonal ice crystals randomly and horizontally oriented in space. The scattering and polarization results for the ice crystals are calculated. The results are compared with measurement data. The single-scattering properties for horizontally oriented columns and plates are presented and used to explain halos and arcs observed in the atmopshere. In the second section, the theory and computations for multiple scattering in cirrus clouds containing oriented ice crystals are presented. The radiative transfer in clouds composed of horizontally oriented ice crystals is formulated. Also, reflected and transmitted intensities, planetary albedo, and polarization in multiple scattering by ice crystals are discussed.

Takano, Yoshihide↗
NASA NTRS1990

Analysis of cirrus optical properties with data from NASA ER2 High-resolution Interferometer Sounder (HIS)

The 8 to 13 micron spectral region is an important atmospheric window for radiometric studies of the Earth's surface and clouds. Most of the Earth-atmosphere longwave radiative loss to space occurs in this spectral region. Selective gaseous absorption in this window occurs in the 9.6 micron ozone band with the remaining absorption dominated by the water vapor continuum. Cirrus clouds have a large impact on the transmittance of this atmospheric window region; it is therefore important to understand the interaction of cirrus cloud with the radiation field for climate studies and in the interpretation of satellite radiometric measurements. The focus was to employ observations of the High-resolution Interferometer Sounder (HIS) made during First ISCCP Regional Experiment (FIRE) to improve the understanding of the radiative properties of cirrus clouds within this window region. Studies were undertaken to investigate the coupling between the microphysical properties of cirrus clouds and their spectral variation within this window region. Extensions of the HIS studies to satellite measurements, with regards to remote sensing and interpretation, were also investigated.

Smith, William L.↗
NASA NTRS1990

Optical properties of marine stratocumulus clouds modified by ship track effluents

The angular distribution of scattered radiation deep within a cloud layer was measured in marine stratocumulus clouds modified by the emissions from ships. These observations, obtained at thirteen discrete wavelengths between 0.5 and 2.3 microns, were obtained as the University of Washington Convair C-131A aircraft flew through a pair of roughly parallel ship tracks off the coast of southern California on 10 July 1987. In the first of these ship tracks, the cloud droplet concentration increased from 40 to 107/cu cm (125/cu cm in the second ship track). Simultaneous to this spectacular change, the aircraft measured interstitial aerosol (Aitken nucleus) concentration that increased from 400 to 1000/cu cm and cloud liquid water content that increased from 0.03 to 0.75 g/cu m. Broadband pyranometer measurements showed that the upwelling flux density increased from 150 to 280 W/sq m. These in-situ microphysics and broadband pyranometer results, together with AVHRR satellite images obtained with the NOAA-10 satellite, are described in detail by Radke et al., (1989). Internal scattered radiation measurements at selected wavelengths obtained with the cloud absorption radiometer (King et al., 1986) for a 100 km section of marine stratocumulus clouds containing these two ship track features are presented.

King, Michael D.↗