Superconducting properties of commercial REBCO-coated conductors with artificial pinning centers

Abstract

Over the last 20 years, technologies for manufacturing rare-earth barium copper oxide (REBCO)-coated conductors have undergone a steady development. Currently, the properties of these conductors are reasonably stable owing to the intensive efforts of the manufacturers. However, for high-field magnet applications, such as the magnets used in nuclear magnetic resonance instruments, accelerators, and fusion reactors, further enhancements in the current-carrying capabilities and/or the current densities of the conductors under a high magnetic field are necessary. Recently, several conductors doped with artificial pinning centers (APCs) have become commercially available, primarily from four manufacturers: Fujikura, Shanghai ST, SuperOx, and SuperPower. In this study, we characterized these relatively new conductors from the viewpoint of a magnet designer. We measured the critical currents (I c) of full-size 4 mm wide conductors in a wide field range at 4.2 K and 77 K; we also measured the critical temperatures. The measurement results showed that the I c values at 4.2 K under perpendicular fields for these conductors are significantly greater than those of non-APC conductors; for the 4 mm wide conductors, the I c values are in the range of 300–740 A and 450–1000 A at 18 T and 12 T, respectively. Furthermore, we clarified that the non-Cu current density (J c) at 4.2 K for some of the investigated conductors is more than twice the J c of the recent Nb3Sn conductors in fields exceeding 15 T. In the investigated commercial REBCO-APC conductors, the highest layer J c of ∼60 kA mm−2 (at 18 T and 4.2 K) was noted. We also investigated the I c–B relationship at 4.2 K for the recent REBCO-APC conductors.