Development of meter-long YBCO coated conductors produced by ion beam assisted deposition and pulsed laser deposition

A "second-generation" of high T-c conductors, consisting of YBCO coatings o n flexible metal substrates, has recently reached a milestone with meter-lo ng tapes capable of carrying over 100 A in a 1 cm width at liquid nitrogen temperature. Having reached this level of performance, however, we have enc ountered difficulties in the self-field characterization of such high curre nt material. In particular, measurement of critical current uniformity alon g the tape length has in Some cases resulted in damage to weaker tape segme nts during measurement of higher-current ones. To address this problem we h ave developed a novel measurement technique that uses permanent magnets to locally suppress the critical current of the tape section being measured to a level that is "safe" for the rest of the tape.