Finite element calculations of local current distribution in anisotropic superconductors in external and self-magnetic field

Current flow in superconductors with nonlinear, anisotropic resistivity was studied using a finite element program. Current distribution, current-voltage curves and critical currents were calculated for different geometrical and electromagnetic parameters. 'Brick-wall' and 'railway-switch' geometries were compared. It was found that in both cases anisotropy of critical current, magnetic self field and external field all lead to inhomogeneous current flow. In extreme cases, only a small fraction of the superconducting volume is utilised for current transport. It is shown directly that critical currents determined in self magnetic field are sample size dependent.