Superconducting Joint Technologies of MgB₂ Wires

Abstract

Magnesium diboride (MgB₂) has a high critical temperature (T_c = 39 K) as a metal-based superconductor and is expected to be used as a superconducting material for liquid helium-free applied equipment. The superconducting joint between MgB₂ wires is an important technology when considering applications of superconducting magnets. In this commentary, we will review the joint techniques that have been applied to MgB₂ wires, and show the results. There are several methods for producing MgB₂ wires, and various methods using wires produced by the in-situ method, ex-situ method, and IMD method were obtained from information from patents and treatises. Some typical methods and problems of some typical ones will be explained. The superconducting joint of MgB₂ wire is relatively easy to accomplish compared to that of other high-temperature superconducting wires, but I_c has not been obtained easily. This is due to the microstructure of the joint interface, and the improvement of those microstructures is considered to be important for the creation of a reliable superconducting joint for MgB₂ in the future.