Thermal reflector to reduce thermal radiation in the entrance of cryogenic instruments

摘要

The entrance of a cryogenic instrument is often a major heat load, since the opening in the cold instrument has a large solid angle. We present a novel thermal reflector that, placed between two openings, reduces the load by reflecting radiation emitted in the hot opening and not directed toward the cold opening. In the Spartan IR Camera, this thermal reflector, placed between the vacuum window and the field stop, reduces the load by a factor of 2.5, which is 1.5 times the limit defined by the size of the field stop, the minimum window size, and the separation between the two.