A design method of flexible thermal strap for cryogenic optics based on pyrolytic graphite film

Flexible thermal strap is a key component for space optical system to realize cold transfer, insulate vibration. The thermal link based on high thermal conductivity graphene film becomes a hot spot for this application. In order to reduce the loss in the heat transfer process, a study on the heat transfer performance and structural form of the thermal link made by pyrolytic graphite films (PGF) is carried out, the thermal resistance network model of the thermal strap is analyzed, the relationship between the heat transfer, the heat transfer temperature difference at the mounting surface and the number of graphite film layers is established by combining theoretical analysis and DOE design methods. A method for quickly determining the design parameters of the thermal strap is proposed. The PGF thermal strap designed according to this method achieves a small temperature difference which less than 1.7K between the cold tip and the simulated optical bench coupling surface, a length of 117mm for the strap, and a weight of only 60g, when it used to transfer 5W cooling capacity at 200K.