An investigation on interface thermal resistance at superconductor cooling by cryocooler

A concept of three-dimensional interfacial layer is presented in the view of micro-nanocryogenics. It is pointed out that solving the problem of interface thermal resistance (ITR) is a key technology for superconductor cooling by cryocooler. The thermal conductivity of Bi-2223 and AlN, the ITR of Bi-2223-to-AlN contact were measured using the axis steady heat flow method. The interface thermal conductance of Bi-2223-to-AlN contact increases with the raising of temperature and contact pressure which ranges from 0.15 to 0.55 MPa. The ITR of Bi-2223-to-AlN contact, at a side temperature of 55 K on Bi-2223 and a contact pressure of 0.55 MPa, is 38.7% of the ITR at a contact pressure of 0.23 MPa, and is 37.9 times larger than the thermal resistance of AlN spacer with a thickness of 10 mm. The ITR in this study is different from the thermal contact resistance of a metal-to-metal or a conventional ceramic-to-ceramic contact