Numerical modeling of heating and current-sharing effects on I-V curves of Y1Ba2Cu3O7 and MgB2 conductors

Numerical modeling of heating and current-sharing effects on I-V curves of Y1Ba2Cu3O7 coated conductors and MgB2 wires was performed using finite element method software. The simulations were made when the conductors carried an over-critical current in steady-state conditions in zero applied magnetic field. Power law current-voltage characteristics typical of the real materials were used. It was assumed that the Y1Ba2Cu3O7 coated conductors were immersed in liquid nitrogen and MgB2 wires in a liquid helium bath. It was found that a bare MgB2 wire starts to be unstable already at applied electric fields >1 μV/cm. Y1Ba2Cu3O7 coated conductor was found to be much more stable, up to applied electric fields ≥104 μV/cm and it can carry an over-critical current ∼1.4Ic