Thermal emission of a two-dimensional rectangular cavity with spatial affine refractive index

The directional emission intensities emerging from a two-dimensional rectangular cavity of semi-transparent media in which is imposed a spatial variable refractive index, have been determined by a curved ray-tracing method determining the trajectories of radiation propagation and integrating the radiative transfer equation on each of these trajectories. Cases of affine refractive indexes with respect to the space variables are examined, for both isothermal and nonisothermal situations, which display significant differences from the case of a constant refractive index. (C) 2000 Elsevier Science Ltd. All rights reserved.