Experimental and numerical study of frequency-dependent transport loss in YBa_2Cu_3O_(7_(δ) coated conductors with ferromagnetic substrate and copper stabilizer

摘要

Although AC transport losses of YBa_2Cu_3O_(7-δ) (YBCO) coated conductors (CCs) have been studied extensively, the frequency dependence of transport losses still needs more investigations. This paper presents a study on the frequency dependence (in the range of 50-1000 Hz) of the transport losses in YBCO CCs with ferromagnetic substrate and copper stabilizer by the use of both experimental and finite element methods (FEMs). The finite element model (FEM) is based on H-formulation and E-J power law, and calculated AC transport losses accord with the experimental ones. The contributions of ferromagnetic (Ni-5at.%W substrate), eddy current (conventional metal), and hysteresis (superconducting YBCO) losses are extracted. It is shown that the AC transport loss per cycle increases with the frequency due to the growing contribution of eddy current loss. More than 80% of eddy current loss comes from the copper stabilizer adjacent to the ferromagnetic substrate. The influence of magnetic substrate on AC loss is also studied, and it is found that YBCO CCs with non-magnetic substrates are more suitable for high-frequency applications.