Evaluation of Interface Resistance in a REBCO Tape at Different Temperatures by Contact-Probing Current Transfer Length Method

The multi-layered structure of a rare-earth barium copper oxide (REBCO) tape causes the resistance of Cu/Ag and Ag/REBCO interfaces (interface resistance), which is a major factor of the resistance of tape-to-tape joints (joint resistance). Interface resistance has been evaluated by the current transfer length (CTL) method. However, induced damage of a part of the measured REBCO tape in this method may cause variations in estimated values, as well as making the tape itself unable to be reused for applications. Therefore, this study proposes the contact-probing CTL method, which is a nondestructive evaluation method of interface resistance. We evaluated the interface resistance in a REBCO tape by the conventional CTL method and the contact-probing CTL method. The estimated interface resistance values by the contact-probing CTL method were more reliable and less varied than those by the conventional method. We also evaluated the temperature dependence of the interface resistance, which is important to analyze joint resistance for various applications of REBCO tapes. The result showed that the interface resistance remained constant at different temperatures.