Numerical Modeling and Experimental Analysis of AC Critical Current in YBCO-Coated Conductors

Critical current is generally defined by the dc measurement at which current produces voltage of E_c = 10^-4 Vm^-1. However, most applications of superconductor are operating at alternating current (ac). Moreover, the ac current-carrying capability of superconductor has attracted extensive attention. This paper is aimed to define the transport ac critical current and put forward a novel electric field criterion based on numerical modeling and experimental analysis. YBCO-coated conductor is investigated because of its power application potential and good anisotropy compared to Bi2223/Ag high-temperature superconductor. On measurement of I-V curves of YBCO-coated conductors at different frequency and liquid nitrogen temperature of 77 K, a novel criterion of transport ac critical current was proposed. Numerical modeling of finite element method was carried out, which was coincident with the experimental results.