We have developed and routinely used reel-to-reel (R2R) scanning Hall-probe microscope (SHPM) and in-line two-dimensional X-ray diffraction (2D-XRD) to characterize REBCO conductors developed at the University of Houston. The SHPM system measures the self-field critical current (I_c) of a REBCO conductor at 77 K, and the in-line 2D-XRD provides the corresponding structural information of the REBCO film over long lengths. We have reported the correlation between the self-field Ic and the integrated XRD peak intensities of REBCO phases. The objective of this work is to extend the R2R characterization of the in-field I_c of long REBCO conductors and correlate the data with nanoscale artificial pinning center (APC) phases in the long tapes. The XRD peak intensity, span, and orientation of the APC phases reflect the inhomogeneity of their distributions in advanced REBCO conductors, which directly affects the in-field I_c. Recently, we developed a new R2R SHPM system, capable of measuring the I_c profile of REBCO conductors over a temperature range of 65–77 K and in an applied field up to 5 T. With the obtained in-field I_c, in conjunction with the corresponding self-field I_c and in-line 2D-XRD structural data, including that of the APC phases, the microstructural reasons for the variation in performance of long REBCO conductors in an applied magnetic field can be determined. This correlation will improve the interpretation of the in-line XRD data, which in turn can be utilized for real-time feedback control of the REBCO film growth and benefit the manufacturing scale-up of advanced REBCO conductors.

This work was supported by the U.S. Naval Sea Systems Command Small Business Technology Transfer award N68335-21-C-0525 and the U.S. Department of Energy Office of High Energy Physics award DE-SC0016220.

Keywords: superconducting tape, in-field, critical current, X-ray diffraction