Self-field critical current of a conductor with an elliptical cross-section

Abstract

Numerical calculations using the commercial finite-element code FEMLAB have beencarried out to find the distribution of current density in a wire of elliptical cross-sectionfrom a hard superconductor carrying the critical current. Dependence of the critical currentdensity on local magnetic field and its orientation has been taken into consideration inthese calculations. The results of critical current calculations for wires of different shapesand dimensions clearly revealed how this quantity can be influenced by the distribution ofthe self magnetic field. The outcome found for wires with cross-sections resembling tapesmade from a high-temperature superconductor Bi-2223 have been approximated by twoengineering formulae: one can be used to cancel out the influence of the tape width, andthe other allows us to perform a correction on the aspect ratio. These expressionswould allow the quality of superconducting properties expressed by the self-fieldcritical current density to be compared also for wires of different cross-sections.