REBCO tapes for applications in ultra-high fields: critical current surface and scaling relations

Abstract

Abstract REBa2Cu3O7−x (REBCO) tapes produced by leading manufacturers were tested at UNIGE to characterize the dependence of the critical current on temperature, field intensity and orientation. This measurement campaign was carried out in the frame of international collaborations having the common goal of developing technology for ultra-high field magnets in the 30–50 T range. The examined samples differ in many respects, e.g. processing methods, thickness of the superconducting layer, Rare Earth element in REBCO, and type of artificial pinning centers (3D nanoparticles vs extended 1D nanorods). We measured the transport critical current of full-width tapes at 4.2 K and 20 K in magnetic fields up to 19 T and at various orientations of the field with respect to the tape surface. Additionally, magnetic characterization was conducted over a wider temperature range (4.2–77 K). The highly engineered vortex pinning results in outstanding critical current performance for all examined tapes: the non-copper critical current density, i.e. the critical current divided by the wire cross-section area minus the Cu area, ranges between 1500 and 2000 A mm−2 at 4.2 K, 19 T and close to 1000 A mm−2 at 20 K, 19 T in the perpendicular field orientation. We obtained scaling expressions for the critical current surface based on the analysis of the pinning-force curves but the pinning-force shape parameters were found to vary from one manufacturer to another. The results presented in this work may offer valuable information not only to magnet designers but also to manufacturers looking to optimize their tapes and achieve better performance.