Abstract
The heat transfer equation derived from the Stefan-Boltzmann law is frequently used to calculate the heat load due to thermal radiation in a cryogenic apparatus. This equation expresses heat transfer from one surface to the other, and includes no information on structures between these surfaces. In the case of thermal radiation through a metal pipe, which exists between different temperature regions, its reflection and conduction in the pipe (funneling) have to be considered. This effect is much larger than the simple estimation derived from the solid angle between these temperature regions. In this paper, the heat transfer equation derived from a ray-trace model and an experiment conducted to confirm it are described. Moreover, the reduction experiment of this heat load using metal baffles is also reported.
