Study on transient heat transfer at metal to dielectric interfaces in the temperature range between 3.5 K and 30 K

Abstract

The thermal conductivity and diffusivity across a combination of metallic and insulating layers are important thermodynamic input parameters for cooling studies of composite materials or assemblies built out of layers of different electrical and thermal conductivity. The dynamic response of such thermal contacts across electrically insulating layers can be expressed in terms of a diffusivity-like value, which is giving insight on the interface thermal resistance. A two-stage cryocooler based test stand is used to measure the thermal conductance of samples. Variable base temperatures of the experimental platform at the cryocooler allow for steady-state and transient heat flux measurements up to 30 K. This paper describes the measurement methodology applied to such kind of non-uniform sample compositions, especially the frequency dependence of the diffusivity values is discussed.