Fatigue Behavior of Critical Current Degradation for YBCO Tapes at 77 K

In the application of high-temperature superconducting (HTS) tapes, they are prone to subject fatigue loadings such as repeated thermal cycles, periodic electromagnetic force, and so on, which will affect the performance of superconductors and lead to the degradation of superconducting magnets and power systems. To optimize the design of a superconducting device, it is important to fully understand the fatigue properties of REBCO conductors. Recently, fatigue loading that influences critical current(I_c)of HTS materials has been studied by several research teams. However, the influence of mechanical fatigue stress on REBCO tapes under background magnetic field has not been reported. In this paper, theI_cas a function of external magnetic field under different loading cycles was investigated at 77 K. The results showed that for fatigue damage of a YBCO-coated conductor, the influence of stress amplitude onI_cdegradation is more significant than the maximum stress applied to the coated conductor. Under higher fatigue load cycles, the YBCO-coated conductor was insensitive to the external magnetic field.