Quantifying the Performance of Multilayer Insulation Technique for Cryogenic Application

Multilayer insulation (MLI) is an important thermal protection system which is used in space cryogenic programs as well as on the ground experiments also. For the continuous and reliable functioning of a cryostat, it is desired to have a minimum heat load to the inner wall of the cryostat, and the need of minimum heat load (radiation heat load in particular) can be well fulfilled by using the MLI technique. It is used to reduce the radiation heat load mainly in the cryostats by placing the radiation shields and spacers in the gap between the two walls (hot and cold surfaces) of the cryostat. The present work is focused on investigation of the suitable reflective layer and spacer materials in MLI systems. In our analysis, Perforated Double-aluminized Mylar (DAM) with Dacron, Unperforated DAM with Silk-net, and Perforated DAM with Glass-tissue have been selected for their evaluation as the reflective layer as well as spacer materials in MLI technique. Current work would discuss the effect of layer density to optimize the layer density and the effect of the number of layers on the heat load. Knowing the key parameters of MLI, the heat load generation in spherical as well as cylindrical cryostats has been compared and the different effect of shielding of the cryostat placing a single layer near the inner or near the outer wall of the cryostat.