Modeling voltage distribution and current limit in Ag/Bi₂Sr₂Ca_n-1Cu_nO_2n+4

Current and voltage distributions in Ag/Bi₂Sr₂Ca_n-1Cu_nO_2n+4 (BSCCO) composites are calculated from an analytical model that is based on interfacial resistivity and geometric parameters. The model was verified by measuring the voltage distribution along Ag/Bi₂Sr₂Ca₂Cu₃O₁₀ bars that were fabricated by sinter forging between 400-845 °C and 5-10 MPa. The results show that the solutions depend on a single dimensionless parameter, λL, where L is the length of the interface and λ is associated with resistivity of the Ag (ρ_s), interfacial resistivity (ρ_i) between the Ag and the BSCCO, and thickness of the Ag (d_s). The voltage drop across the interface is proportional to (ρ_iρ_s/d_s)^1/2. The model was extended for powder-in-tube tapes to examine the effects of cracking on critical current density.