Theory of flux cutting and flux transport at the critical current of a type-II superconducting cylindrical wire

Article

关键词: LONGITUDINAL MAGNETIC-FIELD;    HELICAL VORTEX INSTABILITY;    FORCE-FREE CONFIGURATIONS;    CRITICAL-STATE MODEL;    HARD SUPERCONDUCTORS;    VORTICES;    LINE;    SURFACE;    CYLINDER;    LOSSES;   

DOI  :  10.1103/PhysRevB.83.214511

来源: SCIE

【 摘 要 】

I introduce a critical-state theory incorporating both flux cutting and flux transport to calculate the magnetic-field and current-density distributions inside a type-II superconducting cylinder at its critical current in a longitudinal applied magnetic field. The theory is an extension of the elliptic critical-state model introduced by Romero-Salazar and Perez-Rodriguez. The vortex dynamics depend in detail on two nonlinear effective resistivities for flux cutting (rho(parallel to)) and flux flow (rho(perpendicular to)), and their ratio r = rho(parallel to)/rho(perpendicular to). When r < 1, the low relative efficiency of flux cutting in reducing the magnitude of the internal magnetic-flux density leads to a paramagnetic longitudinal magnetic moment. As a model for understanding the experimentally observed interrelationship between the critical currents for flux cutting and depinning, I calculate the forces on a helical vortex arc stretched between two pinning centers when the vortex is subjected to a current density of arbitrary angle phi. Simultaneous initiation of flux cutting and flux transport occurs at the critical current density J(c)(phi) that makes the vortex arc unstable.

【 授权许可】

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