We have succeeded in evaluating local critical current (Ic) and n-indices in a long-length GdBCO coated conductor as a function of longitudinal coordinate with a spatial resolution of 1 mm under external magnetic fields up to 5 T at both temperatures of 77 K and 65 K. While the sample was carried in reel-to-reel manner in a liquid nitrogen bath with an external magnetic field, we measured magnetization of the tape continuously. The temperature was varied down to 65 K by using a subcooled liquid nitrogen circulation system. This allows us to evaluate spatially-resolved in-field Ic distribution in the long-length tape. A method to evaluate position dependent n-indices based on the magnetization measurements was also proposed. We’ve confirmed the validity of the analyses by comparing the results with site-specified transport measurements by the four-probe method using the same sample. These characterizations are very useful to understand the current transport properties in the full-length of the coated conductors including the influence of localized flux flow dissipation originating from the positional variation of Ic in the tape strand under practical operation conditions not only 77 K, self-field. Namely, this method has a strong impact on the characterization of long-length coated conductors for magnet applications.
Acknowledgements: This work was supported by “JSPS KAKENHI (16H02334)”.