Fabrication and Test of Indium-Plated Solder Welding NbTi Superconducting Joint

Superconducting joints are essential for the persistent-mode operation of superconducting magnet systems. However, defects such as holes, which are commonly observed in NbTi superconducting joint prepared by solder welding method, can seriously affect the stable operation of superconducting magnets. Therefore, in this paper, an indium-plated solder welding method is proposed to prepare NbTi superconducting joint, and the holes between the NbTi filaments and the solder matrix are effectively eliminated by indium-plated operation, thus making them tightly connected. In addition, the superconducting property tests on the solder matrix showed excellent superconductivity with Tc of 8.4 K and Jc of 105 A⋅cm−2 at zero background magnetic field. Ultimately, the resistance tests conducted on the joints under a 1T background magnetic field show that the joints’ resistance can reach an order of 10–13 Ω, which fully meets the operational requirements for NbTi superconducting magnets.