Development of a Superconducting Joint for High Field NMR

The innermost coil of a new high-field NMR magnet such as a 1-GHz NMR magnet is designed by using a new superconductor. It is therefore important that a superconducting joint between the new superconductor and the NbTi conductor was developed. We have developed a new superconducting joint method for the Nb
₃
Al conductor, which is expected to be used for the innermost coil of the 1-GHz NMR magnet. This joint method uses the Nb
₃
Sn layer that is formed on the Nb matrix surface of the Nb
₃
Al conductor. This Nb
₃
Sn layer enables the soldering of the Nb
₃
Al conductor; thus, it is possible to solder the Nb
₃
Al conductor and NbTi conductor. The superconducting property of the Nb
₃
Al-NbTi joint that is joined by the superconducting solder (for example, SnBiPb solder) showed good performance under a magnetic field of 0.1 T