Critical current increase of high-T c superconductor pipe with coaxial configuration

Abstract

The critical current (Ic) of high-Tc pipe-like superconductor was found to increase under external magnetic field, when the superconductor pipe and bar are constructed into coaxial cylinder configuration. The superconductor specimens in the Bi-Sr-Ca-Cu-O system used were fabricated by a glass-ceramic method. When the currents in the inner bar are made to flow in the opposite direction against the outer pipe, the critical current of the pipe is observed to increase by a measurable amount, although the pipe is exposed to the magnetic field produced by the inner conductor current. This phenomenon was observed not only in direct current but also in alternating current.