Theoretical investigation on spectral emissivity of thermal control coatings with optical-rough surface

A theoretical model for calculating the spectral emissivity of the thermal control coating with rough surfaces is proposed based on the Monte Carlo method in this paper. Instead of treating the surface of the coating as a smooth surface, a diffuse surface or a rough surface using an empirical formula, the model applies a Gaussian random rough surface to the spectral emissivity calculation of the coating. Firstly, the Gaussian rough surface is established, and its properties are mainly determined by two parameters: the root-mean-square roughness(δ) and the coherent length(l). Then the spectral emissivity model of the thermal control coating with the rough surface is established by Monte Carlo method. The directional spectral emissivity of the smooth surface and the rough surface with different roughness is compared. Finally, the reasons for their differences in spectral emissivity are explained.