Showing papers on "Thermal radiation published in 1969"
TL;DR: In this paper, the atmospheric radiation R integrated over all wavelengths, is specified solely in terms of the screen-level air temperature T as R = σT4{1 - c exp [−d (273 - T)2]}, where c and d are constants having values of 0.261 and 7.77×10−4, respectively.
Abstract: A theoretical analysis of atmospheric thermal radiation reveals that previous formulas relating this parameter to screen-level air temperature have lacked universal applicability. New considerations indicate that the effective emittance of the atmosphere is a minimum at 273°K and that it increases symmetrically to approach unity exponentially at higher and lower temperatures. A formula is developed that meets these standards and fits experimental data from Alaska, Arizona, Australia, and the Indian Ocean with a correlation coefficient of 0.992. The atmospheric radiation R integrated over all wavelengths, is specified solely in terms of the screen-level air temperature T as R = σT4{1 - c exp [−d (273 - T)2]}, where c and d are constants having values of 0.261 and 7.77×10−4, respectively. It appears that the formula may be valid at all latitudes and seasons.
461 citations
TL;DR: In this article, a review of the literature in this area is presented, with a focus on gaseous radiation properties of gases and their applications in engineering applications, where the assumption is that the radiating gas under consideration is at the state of complete or local thermodynamic equilibrium and of negligible scattering effect.
Abstract: Publisher Summary This chapter aims to systematically develop the background information needed to formulate and evaluate thermal radiation properties of gases for engineering applications, and to review the literature of present works and approaches for future research in this area. The scope of the chapter is limited by the assumption that the radiating gas under consideration is at the state of complete or local thermodynamic equilibrium and of negligible scattering effect. The chapter introduces the general concepts concerning gaseous radiation and presents a review of the physics of atomic and molecular spectra. The radiation resulting from transitions of electronic, atomic, or molecular states has been discussed; they are line radiation, band radiation, and continuum radiation. The evaluation of total (engineering) emissivity and its applications to radiation from homogeneous gas bodies of complex geometry have been discussed. Consideration has been given to the appropriate absorption coefficients for use in the radiative transport calculations.
257 citations
TL;DR: In this article, a mathematical model was developed to predict radial and axial temperature profiles in an induction-coupled plasma torch, which employed temperature dependent physical properties and included radiation heat loss.
Abstract: A mathematical model was developed to predict radial and axial temperature profiles in an induction‐coupled plasma torch. The model employed temperature dependent physical properties and included radiation heat loss. Temperature fields based on the model were calculated for an atmospheric pressure argon plasma. Computed radial temperature profiles were in agreement with experimental profiles reported in the literature. The gas flow rate and flow pattern in the torch did not greatly affect the radial temperature profiles in the hottest region of the torch under ordinary operating conditions, also in agreement with experiment. A one‐dimensional analysis was developed which predicted these hot‐spot profiles accurately. The plasma model was also found to accurately predict distribution of energy losses from the plasma. Based on the equilibrium current density and temperature profiles provided by the model, the question of the existence of local thermodynamic equilibrium was re‐examined. It was concluded that equilibrium is closely approached in the high‐temperature central portion of the plasma, in agreement with previous investigators; however, nonequilibrium conditions can exist in the region of high temperature gradient at the plasma edge.
108 citations
TL;DR: In this article, a classical statistical thermodynamics in the presence of electromagnetic radiation is reanalyzed, and is reformulated to give a natural classical description of the phenomena which originally led to the introduction of quanta.
Abstract: Classical statistical thermodynamics in the presence of electromagnetic radiation is reanalyzed, and is reformulated to give a natural classical description of the phenomena which originally led to the introduction of the idea of quanta. The traditional classical ideal gas fails to exist in principle for particles of finite mass which have electromagnetic interactions, and hence the classical proofs of energy equipartition are all erroneous. A consistently classical treatment of thermal radiation leads to the natural introduction of temperature-independent fluctuating radiation in the universe. The spectrum of this electromagnetic zero-point radiation may be obtained from the arguments for Wien's displacement law or from the requirement of Lorentz invariance of the radiation spectrum; this zero-point spectrum agrees with the $\frac{1}{2}\ensuremath{\hbar}\ensuremath{\omega}$ per normal mode familiar in quantum theory. The presence of temperature-independent disordered energy from zero-point radiation leads to a contribution to the entropy connected with thermodynamic probability distinct from the contribution of caloric entropy. The use of quanta in calculations of the thermodynamic probability is seen as a subterfuge to account for this mismatch between caloric entropy and probability. Several examples of statistical thermodynamics, which are generally regarded as having their explanation in terms of quanta, allow natural explanations within the context of classical theory with classical electromagnetic zero-point radiation.
73 citations
Patent•
15 Dec 1969TL;DR: In this article, the authors describe a system of co-limitors and lenses with a TIP at the opposite end of a TUBE, which may be used in a high-temperature environment.
Abstract: A SEMICONDUCTOR ELEMENT OF THE KING WHICH PRODUCES AN ELECTRICAL SIGNAL WHICH IS A FUNCTION OF THE INTENSITY OF INCIDENT INFRARED RADIATION IS DISPOSED AT ONE END OF A THIN TUBULAR BODY HAVING A TIP AT THE OPPOSITE END WHICH MAY BE DISPOSED IN A HIGH TEMPERATURE ENVIRONMENT. THE TIP HAS A CONICAL CONFIGURATION TO APPROXIMATE BLACKBODY CHARACTERISTICS AND EMITS THERMAL RADIATION TOWARDS THE DETECTOR THROUGH A SYSTEM OF COLLIMATORS AND LENSES WITHIN THE TUBE. IN ANOTHER EMBODIMENT, THE BODY OF THE DEVICE MAY BE A SOLID QUARTS OR SAPPHIRE ROD HAVING A CONICAL RADIATION OPAQUE TIP AT ONE END AND HAVING A CONCAVE OPPOSITE END TO DEFINE A FOCUSING LENS FOR DIRECTING INFRARED RADIATION ONTO THE DETECTOR ELEMENT.
61 citations
TL;DR: Microwave thermal emission by water measured from aircraft, studying radiation dependence on surface roughness was studied in this paper, where the authors measured the thermal emission from water from aircraft.
Abstract: Microwave thermal emission by water measured from aircraft, studying radiation dependence on surface roughness
45 citations
TL;DR: In this article, the normal mode expansion technique has been used to solve the uncoupled radiative heat transfer problem for an absorbing, emitting, isotropically scattering, nonisothermal, gray medium confined between specularly reflecting, gray parallel boundaries held at uniform but different temperatures.
25 citations
30 Jun 1969
22 citations
TL;DR: The utilization of a mathematical equation and computer techniques for extracting variations from empirical data obtained at relatively low levels of radiation and applying extrapolations of these values in calculations of temperature-time histories at higher levels of irradiance where empirical data are lacking are described.
Abstract: : Prediction of dermal injury resulting from exposure to thermal energy of any given intensity and duration depends entirely upon the resultant skin temperature-time history. Means are now available for assessing heat transfer by low temperature radiation, convection and conduction to the bare skin and through thin protective coverings of known physical properties. However, thermal effects of nuclear detonations constitute a special problem because much of the radiation lies in the visible range where the optical properties of the skin and its coverings, if any, greatly influence the heating pattern. Blackening of the skin eliminates effects due to its optical properties but enhances the ever-present variations in the thermal 'constants' of the skin. The present report describes the utilization of a mathematical equation and computer techniques for extracting these variations from empirical data obtained at relatively low levels of radiation (<0.5 Cal/sq cm sec.), and applying extrapolations of these values in calculations of temperature-time histories at higher levels of irradiance where empirical data are lacking. This procedure is subject to validation by experimentation within a limited range of exposures. If validation is achieved in the blackened skin then the entire system may be utilized in the determination of optical properties of unblackened skin.
TL;DR: Lateral heat conduction and radiation along two parallel long plates separated by nonabsorbing dielectric with refractive index of unity was studied in this paper, where the authors showed that they can be separated by a non absorbing dielectrical material.
Abstract: Lateral heat conduction and radiation along two parallel long plates separated by nonabsorbing dielectric with refractive index of unity
TL;DR: The thermal diffusion equation for solid, homogeneous conductors can usually be solved conveniently using standard Fourier methods as discussed by the authors, however, these solutions cannot be applied when the medium does not behave as a genuine conductor; that is, when convective and radiative processes create energy sources and sinks within the medium.
Abstract: THE thermal diffusion equation for solid, homogeneous conductors can usually be solved conveniently using standard Fourier methods1. These solutions cannot, however, be applied when the medium does not behave as a genuine conductor; that is, when convective and radiative processes create energy sources and sinks within the medium. The effect of absorbed solar radiation on the thermal diffusion in clear ice has been described elsewhere2. In the coastal ablation zone of Antarctica, it causes startling changes in the heat storage in the upper 8 m of the ice, strongly modified overall heat transfer patterns in the ice and increases of the effective thermal conductivity of the medium by factors of up to two. Similar effects on the effective thermal parameters have been obtained in the low density permeable snow medium on the Antarctic Plateau3, although, there, convective transfer of heat in the snow must be taken into account also.
TL;DR: In this article, the authors investigated the evolution of gas clouds of masses, 104, 10 2, 1 and 10 2 M, with the population I composition, both for transparent and opaque stages by comparing the rates of cooling, heating, contraction and expansion.
Abstract: The evolution of gas clouds of masses, 104, 10 2 , 1 and 10- 2 M~_;, with the population I composition is investigated both for transparent and opaque stages by comparing the rates of cooling, heating, contraction and expansion. As heating and cooling processes in the trans parent stage, we consider the thermal radiation from grains, the line-emission by H 2, C+, Si+, C and 0 including the effect of self-absorption, the ionization of atoms by interstellar star light and cosmic-ray particles, and the absorption of star-light by grains. In the opaque stage cooling is due to the diffusion of thermal photons. The results show that in the transparent stage a cloud much greater than 10-2 Me con tracts freely and cools down to about lOoK if its mean density is greater than a certain crit ical value which depends on the mass of the cloud. In the opaque stage the cloud undergoes nearly adiabatic free-fall. On the other hand, if a cloud of mass nearly equal to or smaller than 1 X 10- 2 Me is formed with a mean density greater than a certain critical value, it establishes immediately gravitational equilibrium and the subsequent evolution is the Kelvin contraction.
01 Jan 1969
TL;DR: In this article, the authors present a compilation of data needed for the quantitative description of thermal radiation phenomena in heated air, over a wide range of temperature and density, with the assumption that the air is in a state of local thermodynamic equilibrium.
Abstract: In this volume we present a compilation of data needed for the quantitative description of thermal radiation phenomena in heated air, over a wide range of temperature and density. Use of a temperature to describe the state of the air implies some type of partial thermal equilibrium. In the case of complete thermal equilibrium, there can be only an uninteresting homogeneous system with no net transport of radiation at all. The results presented in this volume have been obtained with the assumption that the air is in a state of local thermodynamic equilibrium (LTE) which means that the matter is in a Maxwell-Boltzmann distribution that is characterized by a single temperature.*
TL;DR: Combined conduction and radiation transfer equations solutions for absorbing-emitting gas, obtaining slip coefficient for diffusion solution correct boundary condition as mentioned in this paper, which is the same as the slip coefficient of diffusion solution.
Abstract: Combined conduction and radiation transfer equations solutions for absorbing-emitting gas, obtaining slip coefficient for diffusion solution correct boundary condition
01 Jun 1969
TL;DR: Apparent thermal radiation properties for one dimensionally rough surface, discussing variance with property models employed in engineering analysis of radiant transfer is discussed in this paper, where the authors discuss variance with properties models employed for radiant transfer.
Abstract: Apparent thermal radiation properties for one dimensionally rough surface, discussing variance with property models employed in engineering analysis of radiant transfer
01 Mar 1969
01 Nov 1969
TL;DR: In this article, the statistical properties of the electrons emitted by a detector, which registers a light beam, contain information about light radiation statistics, which can give information about the non-linear process and also additional data on the statistics of the transformed radiation.
Abstract: It is known [1–3] that the statistical properties of the electrons emitted by a detector, which registers a light beam, contain information about light radiation statistics. This method has recently been widely used to measure the statistical properties of laser radiation [4]. In analysing non-linearly-transformed laser or thermal radiation, this method can give information about the non-linear process and also additional data on the statistics of the transformed radiation.
TL;DR: In this paper, temperature distribution in shadowed lunar craters formulated in Fredholm integral equations, showing constant temperature and correction for soil thermal inertia, was analyzed. But the authors did not consider the effect of the Earth's magnetic field on the temperature distribution.
Abstract: Temperature distribution in shadowed lunar craters formulated in Fredholm integral equations, showing constant temperature and correction for soil thermal inertia
TL;DR: In this paper, the authors evaluated various radiative transport quantities for a hydrogen plasma, including the Planck mean, modified planck mean and Rosseland mean absorption coefficients, in addition to the modified emissivity and its derivative which appear in the formulation for the linearized radiative flux.
Abstract: The object of this investigation is to evaluate various radiative transport quantities for a hydrogen plasma. These transport quantities pertain to the analysis of radiative energy transfer in nonisothermal gases, and they include the Planck mean, modified Planck mean, linear Planck mean, and Rosseland mean absorption coefficients, in addition to the modified emissivity and its derivative which appear in the formulation for the linearized radiative flux. Twenty one spectral lines are included in the calculations, and the line profiles are taken to be Stark profiles. Results are presented for temperatures from 10 000°K to 20 000°K and electron densities of 1016, 1017, and 1018cm-3. The importance of line radiation, relative to continuum radiation, and the practical achievement of the optically thin and optically thick limits, are discussed.
01 Jan 1969
TL;DR: In this article, the Mie theory is used to compute particle albedos ω 0, phase functions p(cosθ), and extinction cross sections χE for a variety of particle-size distribution functions and complex indexes of refraction n = n ⇔k.
TL;DR: In this paper, a simple nongray radiation balance model is proposed to calculate the mean surface temperature of Venus, which is based upon a balance of net incoming solar radiation and emerging thermal radiation at the top of the atmosphere.
TL;DR: In this article, the interaction between M modes of the radiation field and an active medium in a laser with nonresonant feedback was studied in the HEISENBERG picture.
Abstract: The interaction between M modes of the radiation field and an active medium in a laser with nonresonant feedback (one of the laser mirrors is substituted by a diffusely reflecting medium) is studied in the HEISENBERG picture.
In agreement with [3] the amplitude of the total radiation is found to be stabilized due to the nonlinear interaction, while the radiation corresponding to any of the M modes has properties characteristic of thermal radiation.
TL;DR: In this article, the results of calculations of the thermal radiation from the Moon's surface incident onto a flat surface of unit area located a small distance above the Moon were presented, where the orientation and height of the flat surface vary.
TL;DR: In this article, the authors studied the mechanism of radiation heat transfer, combined with conduction and convection heat transfer in a nonisothermal hydrogen plasma in order to illustrate the effect of radiation in a plasma, where the problem of fully developed laminar flow and heat transfer between black parallel boundaries with a constant wall heat flux is considered.
Abstract: The object of the present work is to study the mechanism of radiation heat transfer, combined with conduction and convection heat transfer, in a nonisothermal hydrogen plasma In order to illustrate the mechanism of radiation in a plasma, the problem of fully developed laminar flow and heat transfer between black parallel boundaries with a constant wall heat flux is considered The assumptions of linearized radiation and local thermodynamic equilibrium are made The results are presented in terms of dimensionless bulk gas temperatures The influence of line radiation compared to continuum radiation is investigated Optically thin results, optically thick results, and results obtained from a nongray differential approximation are compared to the results obtained from the general equation The results show that the optically thin solution and also the differential approximation results greatly over-estimate the influence of radiation The optically thick solution does not appear to be useful since it gives the result that the bulk temperature is approximately equal to the wall temperature For lower pressures, the spectral lines have a significant influence on the dimensionless bulk temperature, but at higher pressures the line effect becomes negligible
Patent•
26 Feb 1969TL;DR: In this paper, two integrating spheres having the same configuration are provided to be heated by incident radiation collected from an outside energy source of unknown power, and the second sphere is heated resistively to the same temperature attained by the first sphere.
Abstract: There are provided two integrating spheres having the same configuration. One of the integrating spheres is heated by incident radiation collected from an outside energy source of unknown power. The second sphere is heated resistively to the same temperature attained by the first sphere. The electrical heating of the second sphere is controlled by a servo loop activated from a single detector which alternately senses thermal radiation from the two spheres. Electrical power delivered to the heating element in the second sphere is measured by a power meter and directly equals the radiative power incident in the first sphere.
TL;DR: In this paper, the thermal diffusivity of a small solid disk whose diameter is not very large compared with its thickness is determined by considering thermal radiation losses not only from the front and rear faces but also from the lateral face of the disk.
Abstract: A theoretical study was undertaken for developing a procedure for measuring by transient methods the thermal diffusivity of a small solid disk whose diameter is not very large compared with its thickness. The disk is placed in a vacuum furnace and heated on one face by a radiant heat source whose intensity is varied step-wise. Thermal radiation losses not only from the front and rear faces but also from the lateral face of the disk are considered. The results established that, if the ratio 2r0/l (2r0: diameter, l: thickness) of the disk is larger than 6, the thermal diffusivity can be determined within 1.0% error by reckoning with the disk regarded as a infinite slab. If 2r0/l_??_6, the thermal diffusivity should be determined by the present theory which takes into account thermal radiation losses from all faces of the disk. We further find from the present theory that if 2r0/l_??_2 and that at the same time the thermal radiation losses are large' it should be difficult to measure thermal diffusivity with high accuracy.
TL;DR: In this paper, the authors carried out observations of the galactic background continuum radiation with an angular resolution of 11 arc min at a frequency of 15 GHz, which is higher than those of any previous observations of this type.
Abstract: WE have carried out observations of the galactic background continuum radiation with an angular resolution of 11 arc min at a frequency of 15 GHz. This frequency is higher than those of any previous observations of this type1–7. The aim of our observations, made in November 1971, was to determine the brightness of the background radiation at a very high frequency where a contribution of the thermal radiation to the total background is larger than at the lower frequencies. This enables a spectral separation of the background radiation into thermal and nonthermal components.