Development of Superconducting Coil Using Bi-2212/Ag Tapes

Many investigations for practical use of oxide superconducting tape and wire are in progress.1–7 We are developing superconducting coils using Bi2Sr2CaCu2O x (Bi-2212)/Ag composite tapes. The Bi-2212/Ag tapes prepared by the melt-solidification method have an excellent microstructure of highly oriented and densely stacked Bi-2212 crystals with their ab-plane parallel to the silver tape surface. Owing to this preferable microstructure, they show high J c values, more than 105 A/cm2, even in magnetic fields above 20 T at 4.2 K.8 Therefore, superconducting coils using Bi-2212/Ag tapes are expected to be of practical use as the inner magnet of a hybrid superconducting magnet system, generating more than 20 T at 4.2 K, where application of conventional superconducting materials is difficult because of their low upper critical fields. Furthermore, these coils are expected to be operated around 20 K, where cooling with a refrigerator is possible.