Radiative equilibrium in an atmosphere with constant Einstein absorption coefficient
Radiation equilibrium in atmosphere with constant Einstein absorption coefficient
Schwartz, S.↗
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Results for “RADIATION ABSORPTION”
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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Radiocatalyst for Radiation Protection and Microbial Control
Radiocatalysts are materials that reduce the activation energy required to split water into hydrogen and reactive oxygen species (ROS). They are activated by radiation and can be used to improve the ability of water to act as a radiation barrier. This paper reports the results of an experimental evaluation of a gold radiocatalyst. This work provides a preliminary evaluation of the ability of these types of catalysts to increase the efficiency of water hydrolysis when exposed to different types of radiation (GCR). Although the radiation exposure devices used in this testing were not capable of generating radiation as diverse as is commonly found in space, the testing is useful in evaluating the function of these radiocatalytic nanoparticles when exposed to a a subset of the types of radiation that are found in GCR. The results are relevant to evaluating the use of this material for both space radiation protection and the production of useful byproducts, such as ROS, which can be used to maintain the sterility of stored water supplies. Radiocatalysts are materials typically used in radiation cancer therapy to improve the kill rate of tumors. These nanoparticles can be directly injected into tumors or functionalized to enter tumor cells via the blood stream. When they are exposed to radiation, they produce ROS. ROS are water hydrolysis products such as OH¯, O¯, O3, H2O2. This study used radiocatalytic 1.8 nm gold nanoparticles functionalized with citrate. These nanoparticles were tested through exposure to Xrays, 56Fe particles and gamma rays to demonstrate activity to a variety of radiation sources. The results demonstrate that radiocatalysts can improve the radiation absorption of water by a factor of 3 to 8 and can effectively kill bacteria at radiation levels above 1 Gy.
radiocatalyst radiation protection biocide↗
Comparison of measured and theoretical inverse bremsstrahlung and photoionization absorption of infrared radiation in a H-He plasma.
The absorption coefficients of 1.15- and 3.39-micrometer radiation for a homogeneous H-He plasma have been measured in a temperature and electron density range where the major absorption mechanisms are electron-ion inverse bremsstrahlung and neutral-atom photoionization. Measurements were made behind both the incident and reflected shock waves in a driven tube by recording the laser intensity transmitted along the tube diameter as a function of time. The measured values compare well with those obtained from theoretical calculations for a gas in thermodynamic equilibrium.
Billman, K. W.↗
Absorption of solar radiation by alkali vapors
A theoretical study of the direct absorption of solar radiation by the working fluid of high temperature, high efficiency energy converters has been carried out. Alkali vapors and potassium vapor in particular were found to be very effective solar absorbers and suitable thermodynamically for practical high temperature cycles. Energy loss via reradiation from a solar boiler was shown to reduce the overall efficiency of radiation-heated energy converters, although a simple model of radiation transfer in a potassium vapor solar boiler revealed that self-trapping of the reradiation may reduce this loss considerably. A study was also made of the requirements for a radiation boiler window. It was found that for sapphire, one of the best solar transmitting materials, the severe environment in conjunction with high radiation densities will require some form of window protection. An aerodynamic shield is particularly advantageous in this capacity, separating the window from the absorbing vapor to prevent condensation and window corrosion and to reduce the radiation density at the window.
Mattick, A. T.↗
Hazards protection for space suits and spacecraft
A flexible multi-layered covering article for protection against the hazards of exposure to the environment of outer space is disclosed. The covering includes an outer layer section comprising an outermost lamina of woven expanded tetrafluoroethylene yarns (Gore Tex) for protecting against abrasion and tearing, an underlying weave of meta-aramid yarns (Nomex) and para-aramid yarns (Kevlar) for particle impart protection, and electrostatic charge dissipation and control system incorporated therein, and a chemical contaminants control barrier applied as a coating. A middle section includes a succession of thermal insulating layers of polymeric thermoplastic or thermoforming material, each of which is coated with a metal deposit of high infra-red emissivity and low solar radiation absorption characteristics and separated from adjacent insulating layers by a low thermal conductance material. The covering further includes a radiation attenuating layer of a tungsten-loaded polymeric elastomer binder for protecting against bremsstrahlung radiation and an inner layer of rip-stop polyester material for abrasion protection. A chloroprene coating may be supplied the polyester-material for added micrometeroid protection. Securing means of low heat conductance material secures the multi-layers together as a laminar composite.
Kosmo, Joseph J.↗
Absorption of Solar Radiation by Clouds: An Overview
This talk provides an overview of the subject of absorption of solar radiation by clouds in the earth's atmosphere. The paper summarizes the available evidence which points to disagreements between theoretical and observed values of cloud absorption (and reflections). The importance of these discrepancies, particularly to remote sensing of clouds as well as to studies of cloud physics and earth radiation budgets, is emphasized. Existing cloud absorption and reflection measurements are reviewed and the persistent differences that exist between calculated and measured near-infrared cloud albedos are highlighted. Various explanations for these reflection and absorption discrepancies are discussed under two separate paths: a theoretician's approach and an experimentalist's approach. Examples for the former approach include model accuracy tests, large-droplet hypothesis, excess absorbing aerosol, enhanced water vapor continuum absorption, and effects of cloud inhomogeneity. The latter approach focuses on discussions of instrumental device, calibration, operational strategy, and signal/noise separation. A recommendation for future activities on this subject will be given.
Tsay, Si-Chee↗
Thermal response to ozone fluctuations of the stratosphere
Correlations between stratospheric meteorological parameters and ozone amount are examined in terms of radiation absorption by ozone. Fluctuations of ozone concentration at subtropic latitudes in summer are analyzed on the assumption that local temperature is governed entirely by radiative equilibrium. The analysis suggests that the fluctuations of mean monthly temperature and ozone are not only correlated, but also follow the order-of-magnitude values expected if ozone heating dominates the temperatures. Most direct control of ozone on temperature exists in the lowest parts of the stratosphere.
Stanulonis, S. F.↗
A parameterization for the absorption of solar radiation by water vapor in the earth's atmosphere
A parameterization for the absorption of solar radiation as a function of the amount of water vapor in the earth's atmosphere is obtained. Absorption computations are based on the Goody band model and the near-infrared absorption band data of Ludwig et al. A two-parameter Curtis-Godson approximation is used to treat the inhomogeneous atmosphere. Heating rates based on a frequently used one-parameter pressure-scaling approximation are also discussed and compared with the present parameterization.
Wang, W.-C.↗
Absorption of Solar Radiation by Clouds: Observations Versus Models
There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.
Cess, R. D.↗
Parameterizations for the absorption of solar radiation by O2 and CO2 with application to climate studies
Simple and accurate parameterizations have been developed for computing the absorption of solar radiation due to O2 and CO2. The parameterizations are based on the findings that temperature has a minimal effect on the absorption and that the one-parameter scaling can be applied to take into account the effect of pressure variation along a path. Overlapping of the absorption due to CO2 and water vapor is treated accurately in the parameterizations. Simulations with a zonally averaged multilayer energy balance model show that the absorption of solar radiation due to O2 and CO2 has a small, albeit nonnegligible, effect on climate. The global surface solar radiation is reduced by 2.2 W/sq m, and the warming of the surface temperature due to a doubled CO2 concentration is reduced by 10 percent in the Northern Hemisphere.
Chou, Ming-Dah↗
Direct measurements of density in the thermosphere.
Falling sphere, solar XUV radiation absorption and pressure gauge mass spectrometry for density measurements of thermosphere, comparing results and noting discrepancies
MASS SPECTROMETRY↗
Air radiation graphs - Spectrally integrated fluxes including line contributions and self absorption
Air radiation graphs - spectrally integrated fluxes including line contributions and self- absorption
RADIATION EMISSION↗
Thermophysics Characterization of Multiply Ionized Air Plasma Absorption of Laser Radiation
The impact of multiple ionization of air plasma on the inverse Bremsstrahlung absorption of laser radiation is investigated for air breathing laser propulsion. Thermochemical properties of multiply ionized air plasma species are computed for temperatures up to 200,000 deg K, using hydrogenic approximation of the electronic partition function; And those for neutral air molecules are also updated for temperatures up to 50,000 deg K, using available literature data. Three formulas for absorption are calculated and a general formula is recommended for multiple ionization absorption calculation. The plasma composition required for absorption calculation is obtained by increasing the degree of ionization sequentially, up to quadruple ionization, with a series of thermal equilibrium computations. The calculated second ionization absorption coefficient agrees reasonably well with that of available data. The importance of multiple ionization modeling is demonstrated with the finding that area under the quadruple ionization curve of absorption is found to be twice that of single ionization. The effort of this work is beneficial to the computational plasma aerodynamics modeling of laser lightcraft performance.
Wang, Ten-See↗
A simplified method for calculating the atmospheric heating rate by absorption of solar radiation in the stratosphere and mesosphere
Calculations of the atmospheric heating rate by absorption of solar radiation by O3, H2O, and CO2 are reported. The method needs only seven parameters for each molecule and is particularly useful for heating calculations in three-dimensional global circulation models below 80 km. Applying the formula to the observed distributions of O3, H2O, and CO2 produces reasonable latitudinal and seasonal variations in the heating rate. The calculated heating rate, however, is sensitive to the global distributions of the absorbing gases, and uncertainties in the O3 distribution above approximately 50 km and the H2O distribution below approximately 20 km may seriously affect the global distributions of the heating rate in these regions.
Shimazaki, T.↗
Absorption of Solar Radiation by Clouds: Interpretations of Satellite, Surface, and Aircraft Measurements
To investigate the absorption of shortwave radiation by clouds, we have collocated satellite and surface measurements of shortwave radiation at several locations. Considerable effort has been directed toward understanding and minimizing sampling errors caused by the satellite measurements being instantaneous and over a grid that is much larger than the field of view of an upward facing surface pyranometer. The collocated data indicate that clouds absorb considerably more shortwave radiation than is predicted by theoretical models. This is consistent with the finding from both satellite and aircraft measurements that observed clouds are darker than model clouds. In the limit of thick clouds, observed top-of-the-atmosphere albedos do not exceed a value of 0.7, whereas in models the maximum albedo can be 0.8.
Cess, R. D.↗
Absorption of Solar Radiation by Clouds: Interpretations of Satellite, Surface, and Aircraft Measurements
To investigate the absorption of shortwave radiation by clouds, we have collocated satellite and surface measurements of shortwave radiation at several locations. Considerable effort has been directed toward understanding and minimizing sampling errors caused by the satellite measurements being instantaneous and over a grid that is much larger than the field of view of an upward facing surface pyranometer. The collocated data indicate that clouds absorb considerably more shortwave radiation than is predicted by theoretical models. This is consistent with the finding from both satellite and aircraft measurements that observed clouds are darker than model clouds. In the limit of thick clouds, observed top-of-the-atmosphere albedos do not exceed a value of 0.7, whereas in models the maximum albedo can be 0.8.
Cess, R. D.↗
Continuum Absorption Coefficient of Atoms and Ions
The rate of heat transfer to the heat shield of a Jupiter probe has been estimated to be one order of magnitude higher than any previously experienced in an outer space exploration program. More than one-third of this heat load is due to an emission of continuum radiation from atoms and ions. The existing computer code for calculating the continuum contribution to the total load utilizes a modified version of Biberman's approximate method. The continuum radiation absorption cross sections of a C - H - O - N ablation system were examined in detail. The present computer code was evaluated and updated by being compared with available exact and approximate calculations and correlations of experimental data. A detailed calculation procedure, which can be applied to other atomic species, is presented. The approximate correlations can be made to agree with the available exact and experimental data.
Armaly, B. F.↗
Low Reynolds Number Droplet Combustion In CO2 Enriched Atmospheres In Microgravity
The effect of radiative feedback from the gas phase in micro-gravity combustion processes has been of increasing concern because of the implications in the selection and evaluation of appropriate fire suppressants. The use of CO2, an optically thick gas in the infrared region of the electromagnetic spectrum, has garnered widespread acceptance as an effective fire suppressant for most ground based applications. Since buoyant forces often dominate the flow field in 1-g environments the temperature field between the flame front and the fuel surface is not significantly affected by gas phase radiative absorption and re-emission as these hot gases are quickly swept downstream. However, in reduced gravity environments where buoyant-driven convective flows are negligible and where low-speed forced convective flows may be present at levels where gas phase radiation becomes important, then changes in environment that enhance gas phase radiative effects need to be better understood. This is particularly true in assessments of flammability limits and selection of appropriate fire suppressants for future space applications. In recognition of this, a ground-based investigation has been established that uses a droplet combustion configuration to systematically study the effects of enhanced gas phase radiation on droplet burn rates, flame structure, and radiative output from the flame zone.
Hicks, M. C.↗