Constant radiation power density

Fig. 1 Matching of current-voltage characteristics of solar cell and electrolyzer (a) at constant light power density 1, 2, 3 - characteristics of solar cell at Ng = 1,2, and 4 (at Sj = const) 4 - characteristic of electrolyzer (Ng = 1) o - maximum power point (MPP) dashed line shows the locus of maximum cell output power at the given radiation power density (b) at varying radiation power density 1 , 2, 3, -characteristics of solar cell dashed line - locus of MPP hatched area - variations of MPP in the most probable limits of variation of the light power density and temperature 4 - characteristic of electrolyzer.

The integral of the temperature gradient of the spectral power density from wavelength Xl to X2, is readily calculable using the Planck radiation law (5). Constant emissivity is assumed for equation 3. 

T -Tg. and x = pcVIhS and assuming a constant fraction of the power density is lost by radiation to the surroundings,... 

A giant optical nonlinearity of self-focusing type in the oriented mesophase of nematic liquid crystals (NLC) due to the director reorientation under the action of a light wave field is predicted. Self-focusing of He-Ne laser radiation with power lO" W and power density - 50 W/cm in a planar oriented 60 jum thick NLC layer has been carried out experimentally. The measured value of the nonlinearity effective constant 2 0.07 cm /erg corresponds to theoretical predictions, and turns out to be larger than the CS2 nonlinearity by sl0 times. 

A substance or device (synonymous with neutral density filter) that reduces the radiant power of incident radiation by a constant factor over all wavelengths within the instrument s operating range. See also Filter... 

Thus the energy density of the radiation in a Prevost chamber and the emissivity of a perfect black body are both proportional to the fourth power of the absolute temperature. The constant (T is of universal significance, and applies to all black bodies of whatever materials they may be composed. 

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