Superconducting currents of scarf joints between single-core ex-situ MgB2 wires

Abstract Superconducting joints between single-core MgB2/Fe wires made by ex-situ Powder-in-Tube (PIT) process were manufactured using scarf joint architecture. MgB2 powder of variable particles and different deforming ratio were applied for the set of joints annealed finally at 950 oC/30 min. The critical transport currents of joints were measured at 4.2 K and external magnetic fields up to 6 T and compared with the currents of not joined MgB2/Fe wires. Structure of joints interfaces were analysed by optical microscopy. The joint’s transport current is dominantly affected by the applied deformation by pressing, which is optimally ~ 20 %. It was also found that addition of finer MgB2 powder between the joined wires allows the creation of better-connected superconducting current paths. Presented results show that the scarf joints architecture is simple process, which could be possibly used for the fabrication of superconducting joint of MgB2 coil working in persistent mode.