Iron-based superconductors (IBS) are very promising candidates for high-field applications owing to their ultrahigh upper critical field (H_c2) and very small anisotropy. For the practical applications, IBS wires and tapes with high transport critical current density (J_c), high mechanical strength and sufficient length are crucial. In the recent years, high transport Jc up to 1.5×10⁵ A cm^-2 at 4.2 K and 10 T was achieved in highly textured IBS tapes based on a powder-in-tube (PIT) method. Furthermore, the transport J_c of IBS tapes with high-strength composite metal sheath such as Cu/Ag and Stainless steel/Ag was enhanced above 10⁵ A cm^-2 at 4.2 K and 10 T as well. On the other hand, with hot isostatic pressing process, the J_c-performance of IBS round wires was also significantly improved. In this presentation, key elements and underlying issues for achieving higher J_c are identified and discussed in terms of the current state of the art. For further promoting the practical application of IBS, 100-meter class IBS wires were successfully developed, and their transport J_c was recently enhanced to 5×10⁴ A cm^-2 at 4.2 K and 10 T. With the achievement of high-performance multifilamentary IBS long-length tapes, the first IBS single pancake coil and double pancake coil were fabricated and tested at 24 T and 30 T background field, respectively. Two IBS racetrack coils using 100-meter long IBS tapes were made and tested in a superconducting dipole magnet which provided a maximum background field of 10 T at 4.2 K. These results demonstrate the great potential of IBS wires in high-field applications in the future.

Keywords: iron-based superconductor, critical current density, wire, coil