Thermal radiation irradiation

Irradiation G Total thermal radiation energy incident on a surface per unit time per unit area Irradiation (G), and Radiosity J) are all energy fluxes (i.e., rate... 

A discussion of the coincidence technique with some general applications has been published by Wahlgren, Wing and Hines 71>. Many of the early applications of the technique made use of the fact that 64Cu is one of the few radionuclides produced by thermal neutron irradiation for which the 0.511 MeV positron annihilation photopeak is a prominent feature of the spectrum. Copper has been determined in meteorites 72> and copper ores 73,74) ]-,y coincidence counting of 04Cu annihilation radiation. The rapid and selective nature of the determination may have important applications in the on-line sorting of copper ores. 

Solar radiation is a form of thermal radiation having a particular wavelength distribution. Its intensity is strongly dependent on atmospheric conditions, time of year, and the angle of incidence for the sun s rays on the surface of the earth. At the outer limit of the atmosphere the total solar irradiation when the earth is at its mean distance from the sun is 1395 W/m2. This number is called the solar constant and is subject to modification upon collection of more precise experimental data. 

Besides the absorption of the various components of solar irradiation, additional infrared (IR), or thermal, radiation is also absorbed by a leaf (see Eq. 7.2 and Fig. 7-1). Any object with a temperature above 0 K ( absolute zero ) emits such thermal radiation, including a leaf s surroundings as well as the sky (see Fig. 6-11). The peak in the spectral distribution of thermal radiation can be described by Wien s displacement law, which states that the wavelength for maximum emission of energy, A,max, times the surface temperature of the emitting body, T, equals 2.90 x 106 nm K (Eq. 4.4b). Because the temperature of the surroundings is generally near 290 K, A,max for radiation from them is close to... 

D. Under the conditions of C, what percentage of the energy input by absorbed irradiation is dissipated by the emission of thermal radiation ... 

The condition on the temperature may be relaxed if the SSE system is irradiated with microwave pulses of short duration only. In this case we may work at considerably higher temperatures, arguing that, owing to the short interaction times, the thermal radiation does not have enough time to destroy quantum coherence. This argument is used and found to be valid in atomic fast beam experiments (see, e.g., Moorman and Koch (1992)) that are conducted at room temperature. 

Effects of Radiation. LA exposed to gamma radiation by Warren et al and by Kosen-wasser, as reported in Ref 139, exhibited post-irradiation gas evolution as measured by vac stab test appar. Bowden Singh (Ref 135) irradiated Pb, Ag and Cd azides with electrons, neutrons, fission prods and x rays. All azides were exploded by an intense 75-kv electron scream. Thermal neutron irradiation did affect the subsequent decompn of Li and Pb azides. Muraour Ercaud (Ref 129) also subjected LA to a neutron flux. Raney (Ref 158) reported that a total flux of 7.5 10 ... 

Since about 1930 a great number of papers concerned with radiation effects on catalysts have been produced, but very little work in comparison has been done with ion bombardment. The great majority of the papers dealt with 7-, X-ray, electron or thermal neutron irradiations. Some of the later studies using protons, deuterons and a-particles are to some extent comparable to irradiations with ions . In some cases enhancement of the catalytic activity was found, in others in-... 

Convection ceases at the tropopause level, and the temperature in the stratosphere and mesosphere is determined strictly by radiation balance. At altitudes above 20 km the absorption of solar ultraviolet radiation becomes increasingly important. The temperature peak at the stratopause has its origin in the absorption of near-ultraviolet radiation by stratospheric ozone. In fact, the existence of the ozone layer is in itself a consequence of the ultraviolet (UV) irradiation of the atmosphere. The enormous temperature increase in the thermosphere is due to the absorption of extremely shortwaved and thus energetic radiation coupled with the tenuity of the atmosphere, which prevents an effective removal of heat by thermal radiation. Instead, the heat must be carried downward by conduction toward denser layers of the atmosphere, where H20 and C02 are sufficiently abundant to permit the excess energy to be radiated into space. 

Every body emits electromagnetic radiation, but only hot bodies emit thermal radiation with a wavelength in the infrared region. In all cases the irradiance is given by the Stefan-Boltzmann equation ... 

Hence, knowledge of the emissivity completely characterizes the surface. Of course, non-gray and non-diffuse surfaces bring several degrees of complication into the calculations. By employing the concept of radiosity and irradiation illustrated in Figure 7.10, the net thermal radiation heat exchange between surfaces / can be computed by... 

The specimen (800 X 155 mm) is positioned so that its surface is exposed to thermal radiation from a vertical mounted gas-fired radiator, the irradiance decreasing along the specimen s length. A pilot flame is used to initiate flaming at the high radiance end of the sample. 

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