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Results for “VISIBLE 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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Radiative transfer of visible radiation in turbid atmosphere

Methods are presented for solving radiative transfer problems; they include the doubling method and the closely related matrix method, iterative method, Chandrasekhar's method of discrete ordinates, and Monte Carlo method. To consider radiation transport through turbid atmosphere, an atmospheric model was developed characterizing aerosols by parameters. Intensity and polarization of radiation in turbid atmospheres is discussed, as well as lower atmospheric heating due to solar radiation absorption by aerosols.

Yamamoto, G.↗
DOE OSTI2017

Rechargeable solid state neutron detector and visible radiation indicator

A radiation detection device, including: a support structure; and a chalcopyrite crystal coupled to the support structure; wherein, when the chalcopyrite crystal is exposed to radiation, a visible spectrum of the chalcopyrite crystal changes from an initial color to a modified color. The visible spectrum of the chalcopyrite crystal is changed back from the modified color to the initial color by annealing the chalcopyrite crystal at an elevated temperature below a melting point of the chalcopyrite crystal over time. The chalcopyrite crystal is optionally a .sup.6LiInSe.sub.2 crystal. The radiation is comprised of neutrons that decrease the .sup.6Li concentration of the chalcopyrite crystal via a .sup.6Li(n,.alpha.) reaction. The initial color is yellow and the modified color is one of orange and red. The annealing temperature is between about 450 degrees C. and about 650 degrees C. and the annealing time is between about 12 hrs and about 36 hrs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Fe doped TiO{sub 2} photocatalyst for the removal of As(III) under visible radiation and its potential application on the treatment of As-contaminated groundwater

Highlights: • Incorporation of Fe in TiO{sub 2} lattice extended absorption to visible light region. • TiO{sub 2}–Fe 1.0 in anatase crystalline form was synthesized by sol–gel method. • TiO{sub 2}–Fe 1.0 showed the highest photocatalytic activity for As(III) oxidation. • TiO{sub 2}–Fe 1.0 had the highest adsorption capacity for the removal of generated As(V). • TiO{sub 2}–Fe is a promising material on the treatment of As contaminated groundwater. - Abstract: The Fe doped TiO{sub 2} catalyst was evaluated under visible radiation for As(III) removal. The TiO{sub 2}–Fe was synthesized by sol–gel technique at 0.0, 1.0, 2.5, 5.0 and 10.0 wt% iron doping concentrations. The semiconductors were characterized by X-ray diffraction, diffuse reflectance UV–vis, Raman spectroscopy, nitrogen physisorption, SEM–EDS and potentiometric titration for point of zero charge determination. The photocatalytic oxidation of As(III) was assessed in aqueous suspension contained 5 mg L{sup −1} As(III) at pH 7 with 0.25 g L{sup −1} catalyst loading. The incorporation of iron ions in TiO{sub 2} lattice extended the absorption to visible light region and create surface oxygen vacancies which favor photocatalytic oxidation reaction of As(III) using a small doping amount of Fe (1.0 wt%) in TiO{sub 2} powder. Additionally, TiO{sub 2}–Fe 1.0 showed the highest adsorption capacity for As(V) removal compared to sol–gel TiO{sub 2} and P25 indicating that this catalyst is a promising material for As contaminated groundwater treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Morphology and Current Transport in a Thin-Film Polycrystalline Au–Zn{sub x}Cd{sub 1–x}S–Mo Structure with Wide Photosensitivity Range in the Ultraviolet and Visible Radiation Spectral Region

Studies are carried out on the morphology of the surface and photovoltaic characteristics of a thinfilm Au–Zn{sub x}Cd{sub 1–x}S–Mo structural injection photodetector with a wide photosensitivity range in the ultraviolet and visible radiation spectral regions. The composition of Zn{sub x}Cd{sub 1–x}S film in the Au–Zn{sub x}Cd{sub 1–x}S–Mo structure with a wide photosensitivity spectrum in the ultraviolet and visible spectrum, where x on the surface varies from 0.22 to 0.24, is studied. The mechanism of current transport is investigated, and the main electrophysical parameters of the semiconducting materials are determined. The use of Zn{sub x}Cd{sub 1–x}S film with a variable band gap in the thin-film heterojunction solar cells, where they are used as the buffer layer, will provide an opportunity to increase the photosensitivity of the structure in the short-wave region of the radiation spectrum, increase the value of the built-in potential, short-circuit current and value of the open-circuit voltage of the structure.

14 SOLAR ENERGY↗
DOE OSTI2018

Response of Surface Ultraviolet and Visible Radiation to Stratospheric SO 2 Injections

Climate modification by stratospheric SO 2 injections, to form sulfate aerosols, may alter the spectral and angular distributions of the solar ultraviolet and visible radiation that reach the Earth’s surface, with potential consequences to environmental photobiology and photochemistry. We used modeling results from the CESM1(WACCM) stratospheric aerosol geoengineering large ensemble (GLENS) project, following the RCP8.5 emission scenario, and one geoengineering experiment with SO 2 injections in the stratosphere, designed to keep surface temperatures at 2020 levels. Zonally and monthly averaged vertical profiles of O 3 , SO 2 , and sulfate aerosols, at 30 N and 70 N, served as input into a radiative transfer model, to compute biologically active irradiances for DNA damage ( i DNA ), UV index (UVI), photosynthetically active radiation (PAR), and two key tropospheric photodissociation coefficients ( j O1D for O 3 + hν (λ < 330 nm) → O( 1 D) + O 2 ; and j NO2 for NO 2 + hν (λ < 420 nm) → O( 3 P) + NO). We show that the geoengineering scenario is accompanied by substantial reductions in UV radiation. For example, comparing March 2080 to March 2020, i DNA decreased by 25% to 29% in the subtropics (30 N) and by 26% to 33% in the polar regions (70 N); UVI decreased by 19% to 20% at 30 N and 23% to 26% at 70 N; and j O1D decreased by 22% to 24% at 30 N and 35% to 40% at 70 N, with comparable contributions from sulfate scattering and stratospheric O 3 recovery. Different responses were found for processes that depend on longer UV and visible wavelengths, as these are minimally affected by ozone; PAR and j NO2 were only slightly lower (9–12%) at 30 N, but much lower at 70 N (35–40%). Similar reductions were estimated for other months (June, September, and December). Large increases in the PAR diffuse-direct ratio occurred in agreement with previous studies. Absorption by SO 2 gas had a small (~1%) effect on j O1D , i DNA , and UVI, and no effect on j NO2 and PAR.

42 ENGINEERING↗
NASA NTRS1973

Development of an experiment for visible radiation measurements from a satellite

The inversion problem, I.E., determining the atmospheric turbidity from polarimetry of radiation emerging from the earth's atmosphere, is presented. A major theoretical advance was made by finding a successful approximation for the forward peak scattering of aerosols together with a simplified characterization of particle size distributions. An engineering model of a multibarreled photopolarimeter suitable for operation from a satellite was evaluated in laboratory and high altitude jet aircraft tests. Comparison of the data from flights over the Mexican desert with theoretical curves for a Rayleigh atmosphere with negligible turbidity is in agreement.

Sekera, Z.↗
NASA NTRS1981

Absorption of visible radiation by aerosols in the volcanic plume of Mount St. Helens

Samples of particles from Mount St. Helens were collected in both the stratosphere and troposphere for measurement of the light absorption coefficient. Results indicate that the stratospheric dust had a small but finite absorption coefficient ranging up to 2 x 10 to the minus 7 per meter at a wavelength of 0.55 micron, which is estimated to yield an albedo for single scatter of 0.98 or greater. Tropospheric results showed similar high values of an albedo for single scatter

Ogren, J. A.↗
NASA NTRS1981

Absorption of visible radiation in atmosphere containing mixtures of absorbing and nonabsorbing particles

The presence of a strongly absorbing material, tentatively identified as graphitic carbon, or 'soot', is indicated by measurements of single-scattering albedo of tropospheric aerosols. Although theoretical calculations based on models of the ways in which soot may mix with other aerosol materials yield the single-scattering albedo values of 0.6, accounted for by a minimum 20% soot by volume, in urban regions and 0.8, yielded by 1-5% soot by volume, in rural settings, it is found that these same values can be produced by similar amounts of the iron oxide magnetite. Magnetite is shown to be indistinguishable from soot by optical measurements performed on bulk samples, and calculation of various mixtures of soot indicate the difficulty of determining aerosol composition by optical scattering techniques.

Ackerman, T. P.↗
DOE OSTI2013

Variable waveband infrared imager

A waveband imager includes an imaging pixel that utilizes photon tunneling with a thermally actuated bimorph structure to convert infrared radiation to visible radiation. Infrared radiation passes through a transparent substrate and is absorbed by a bimorph structure formed with a pixel plate. The absorption generates heat which deflects the bimorph structure and pixel plate towards the substrate and into an evanescent electric field generated by light propagating through the substrate. Penetration of the bimorph structure and pixel plate into the evanescent electric field allows a portion of the visible wavelengths propagating through the substrate to tunnel through the substrate, bimorph structure, and/or pixel plate as visible radiation that is proportional to the intensity of the incident infrared radiation. This converted visible radiation may be superimposed over visible wavelengths passed through the imaging pixel.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Nd{sup 3+} : YAG laser based on the {sup 4}F{sub 3/2} → {sup 4}I{sub 13/2} secondary transition with a phase-conjugate electro-optically Q-switched open multiloop cavity

Lasing on the {sup 4}F{sub 3/2} → {sup 4}I{sub 13/2} secondary transition (λ = 1.34 μm) in a Nd{sup 3+} : YAG laser with phase conjugation by four-wave mixing directly in the active laser medium was experimentally studied in the regime of electro-optic Q-switching of an open multiloop cavity. The use of an electro-optic Q-switch with a controllable delay of its opening made it possible to increase the amplitude and temporal stabilities of the output laser parameters. The maximum laser pulse energy was 100 mJ at a pulse duration of 120 ns. The phase-conjugate radiation divergence was 0.8 mrad at beam quality . Nonlinear optical conversion of 1.34 μm laser radiation to visible radiation was achieved experimentally. Second and third harmonic generation at wavelengths of 0.67 and 0.446 μm with conversion efficiencies of 25 % and 8 %, respectively, was demonstrated. (lasers)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Simple synthesis of ZnO nanoflowers and its photocatalytic performances toward the photodegradation of metamitron

Highlights: • Fabrication of ZnO nanoflowers assembled from thin and uniform nanosheets. • The material possesses photocatalytic acitivity toward degradation of metamitron. • The catalyst features excellent cycling stability for at least 5 cycle times. • The promising mechanism of photocatalysis of metamitron is also discussed. - Abstract: Large-scale ZnO nanoflowers assembled from numerous thin and uniform nanosheets with a thickness of around 20 nm, were successfully prepared through a facile one-step hydrothermal synthesis route by using zinc acetate, sodium citrate and sodium hydroxide in water solution. The method was simple, green and effective. The obtained ZnO nanoflowers exhibited remarkable photocatalytic acitivity and good cycle stability for the degradation of metamitron under a 300 W of Osram{sup ®} ultra-vitalux lamp light emitting UV and visible radiation over 300–600 nm. UV–vis spectrophotometery was used to measure the rate of photodecomposition of metamitron. The results indicate that about 97% of the metamitron disappeared in the suspension of flower-like ZnO microspheres within four hours, and the degradation efficiency were not changed even after 5 cycle times.

36 MATERIALS SCIENCE↗