The Possible Control Method of Turn-to-Turn Contact Resistivity of REBCO Coil by Surface Coating

In this article, we aim to present a potential control method for managing the turn-to-turn contact resistivity of REBCO coils through surface coating. The current metal insulation (MI) process has been observed to significantly elevate the turn-to-turn contact resistivity in short samples. However, the results from coil sudden discharge experiments do not align with the data obtained from short samples. Furthermore, the substantial variation in contact resistivity among different coils employing the same fabrication process suggests that the MI method may not be the most optimized approach. Consequently, we explored various surface coatings, including stainless steel, copper, and InSn solder. Through a systematic investigation of different combinations of surface coatings on contact resistivity, we discovered that the "Mikic elastic correlation" could effectively describe the turn-to-turn contact resistivity of the REBCO coil. The key to controlling and adjusting the contact resistivity appears to be utilizing a harder, low-conductance, and heterogeneous interface.