CURRENT DISTRIBUTION IN MULTIFILAMETARY SUPERCONDUCTORS AND THEIR QUENCH CURRENT DEGRADATION

When the thickness of the saturated region where the current density r eaches the mean critical current density is larger than some threshold value, flux jump occurs. In multiply-twisted cables, such as ones for AC use, or in complicated magnet systems, such as ones or fusion devi ces, multifilamentary superconductors are exposed to the longitudinal magnetic field that is possible to increase the thickness of the satur ated region and to degrade the quench current. The current distributio n in multifilamentary superconductors is calculated with two models. W ith the first one, its temporal evolution and axial variation can be c alculated. This is also useful to calculate AC losses. In the second m odel, the influence of the transverse magnetic field and the filament diameter as well as of the longitudinal magnetic field is taken into c onsideration. With this model, the transport current at the stability limit against the longitudinal magnetic field instability is estimated . The influences of the critical current density, filament diameter an d conductor diameter on the stability limit are evaluated.