Critical Current Degradation of YBCO Tape With Different Stabilizing Layers Under Cyclic Mechanical Strains

Yttrium Barium Copper Oxide (YBCO) tape has a superconducting layer with a thickness of 1 μm. In the actual operation of YBCO superconducting devices, they may be subjected to mechanical strains produced by electromagnetic and thermal forces. In some cases, these forces may repeat tens of thousands times during their lifetime. We designed and built a cyclic strain test apparatus for HTS tapes, and tested the critical current degradation characteristics of YBCO tapes with two different stabilizing layers. Most of the test samples show extremely small critical current degradation even after 60000 cyclic mechanical strains. But the tapes with stainless steel layer are more likely to suffer from thermal stability problems. Increased current density was observed in the lateral direction when magnetizing the degraded samples.