Thermal Resistance Between Metallic Surfaces of Copper and Stainless Steel at Different Temperatures and Applied Forces for High Current HTS Cable-in-Conduit Conductors

High Temperature Superconductors are a promising option for many superconducting devices like high current conductors for large high-field magnets, current leads, or superconducting coils. Quench propagation in these devices is currently under intensive investigation, and it can be predicted by modelling the entire structure. However, along with thermal material properties, the thermal properties of contact interfaces between structural materials as well as electrical stabilizers are highly needed. So far, a lack of such data in the literature made the analysis of quench propagation very difficult. Thermal resistance of copper-copper and copper-stainless steel interfaces were characterized for different pressure and temperature ranges. Therefore, thermal conductivity was measured with the axial heat flow method within the Physical Property Measurement System of Quantum Design using Thermal Transport Option in the steady-state measurement mode in the temperature range from 4 K to 300 K. For the required investigation, the Thermal Transport Option was extended: the sample puck was equipped with an additional copper frame allowing measurement of the thermal conductance of a stack of metallic plates pressurized by a screw. The method was further extended to allow the measurement of thermal conductance at different applied force values. For this, the copper frame was equipped with strain gauges, and calibrated for measuring the force applied to the stack at different temperatures. Further steps included the systematic measurement of thermal conductance versus temperature of the stacks for a range of applied force values. Two copper stacks composed of copper plates of 100 μm and 200 μm of thickness, and one stack composed of copper and stainless steel plates of 100 μm thickness were investigated. From the measured conductance values, the thermal contact resistance between contacting materials was evaluated.