AC Magnetization Losses in Copper-Stabilized YBCO Coated Conductors Subjected to Repeated Mechanical Stresses

Influence of repeated mechanical stresses on AC losses (transport current and magnetization losses) in YBCO CCs with copper stabilization layers is experimentally investigated. Repeated uni-axial tensile stress-strain was applied to the CC in the longitudinal direction and AC losses were measured electrically at 77 K. Experimental results show that the influence of the repeated mechanical stress/strain on the transport current and magnetization losses are different. In the paper this difference is explained considering that there are two kinds of critical currents of a sample CC which are overall critical current across whole length of the sample CC and local critical current within the sample. These two kinds of critical currents are necessary to take into consideration to understand the AC loss behavior of CCs subjected to repeated mechanical stresses. Local defects in superconducting layers which are developed and grown by repeated mechanical stresses affect the overall and local critical currents differently. Therefore, those defects influence transport current and magnetization losses differently.