Study on current-limiting mechanism of Bi-2223 tape by magneto-optic imaging

Crystalline holes, macroscopic inhomogeneity of superconductivity and weak remnant magnetic fields, directly observed in the metallograph and the magneto-optic images, may indicate the mean reason to limit the critical current density in our silver sheathed Bi1.8Pb0.34Sr2Ca2.2Cu3O8+x 37-filament long tape. The current paths show that thigh supercurrent regions preferentially located at the Bi-2223/Ag narrow interface of filaments.