Inversion of the Temperature Field in Optical Crystals
This article is devoted theoretical and experimental researches of temperature fields which are formed in area semi-transparent, diffusely transmitting and scattering boundary of two optical environments. It is revealed, that thus can arise non-monotonic or at certain conditions completely an inverse temperature field. The phenomenon of inversion of a stationary temperature field is revealed theoretically and subsequently is experimentally confirmed. The specific conditions of occurrence of the phenomenon of inversion are determined. During the crystal growth process behind the front of crystallization there can be a congestion of impurities or micro-bubbles which are grasped by the moving front of crystallization. It results in occurrence diffusely transmitting and scattering boundary on which the radiating thermal flux going from the melt is dissipated in a growing crystal. In turn under the certain conditions it could result in non-monotonic of temperature field in area of phase boundary and even in full inversion. The experimental equipment was developed and results of experimental measurements which completely confirm theoretical conclusions are given. The described phenomenon could be meet in growing of such optical crystals as sapphire, ruby, fluorides etc. It is specified, that the similar conditions can arise as well on boundary of solid-gas and liquid-gas.