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From an engineering standpoint, the magnetic field (B), temperature (T), and strain dependence (ε) of the critical current density (JC) in practical superconducting wires/tapes is critical for optimizing device design using superconducting technology. The highly anisotropic and brittle nature of YBa2Cu3O7-δ (YBCO) coated conductor tapes means a detailed investigation of the parameters that affect the critical current is a challenging experimental task to achieve within a single strain apparatus. Here we present critical current measurements as a function of strain on YBCO coated conductors made using a bending apparatus designed for use in horizontal split-pair magnet systems with a 40 mm diameter bore. The design and configuration of the apparatus allows different compressive and tensile strain between -1.4% <; εapplied <; +0.5% to be applied. Magnetic fields up to 0.7 T at T=77 K , and 15 T at 4.2 K, were applied at different angles (θ) with respect to the coated conductor surface. At 77 K, JC can be reversibly reduced by more than 85% with a ~ -1% compressive strain at 0.7 T. For high compressive strains, JC versus strain data show convex behavior. We provide a preliminary parameterization of the scaling relation for JC (B,T,ε,θ).
Date of Publication: June 2011