Thermal Resistance Across a Copper/Kapton/Copper Interface at Cryogenic Temperatures
The high-Tc superconductor current lead heat intercept connection, which is utilized as a thermal intercept to remove the Joule heat from the upper stage lead to a heat sink operating at 50 – 77 K, consists of a structure where a 152-µm film is sandwiched between two concentric copper cylinders. The material chosen for the insulating film is Kapton MT,* a composite film which has a relatively low thermal resistance, but yet a high voltage standoff capability. Here, the measured thermal conductance of a copper/Kapton MT/copper junction in a flat-plate geometry is compared to the results obtained from the actual heat intercept connection. Increasing the contact pressure reduces the thermal resistance to a minimum value determined by the film conduction resistance. A comparison between the resistance of the copper/Kapton MT/copper junction and a copper/G-10/copper junction demonstrates that the Kapton MT layer yields a lower thermal resistance while still providing adequate electrical isolation.
KeywordsNickel Helium Polyimide Bali
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