Characterization of Individual Filaments in a Multifilamentary YBCO Coated Conductor

Striation of wide YBCO coated conductor tapes is necessary to reduce the hysteresis losses. However, the processes used to striate the films may adversely affect the overall critical current of the tape not only by simple removal of superconducting material, but by introducing additional defects. We studied the transport properties of individual filaments of a filamentary YBCO tape on Hastelloy substrate striated by laser ablation. The tape consisted of 24 parallel filaments 0.5 mm wide, covered by thin Ag layer. I-V curves on 9 cm long filament sections as well as the changes of the critical current along the filament were measured at 77 K in magnetic fields up to 70 mT. 8 of 24 filaments were experimentally characterized by the mean value of the critical current and the associated n-value. The best filament had a critical current of ~7 A at 1 microvolt/cm and B = 0.