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

TitleTheory of flux cutting and flux transport at the critical current of a type-II superconducting cylindrical wire
Publication TypeJournal Article
Year of Publication2011
AuthorsClem JR
Journal TitlePhysical Review B
Volume83
Pages214511
Date Published06/09
ISBN Number1098-0121
Accession NumberISI:000291432700008
Keywordscritical-state model, cylinder, force-free configurations, HARD SUPERCONDUCTORS, helical vortex instability, line, longitudinal magnetic-field, losses, surface, vortices
Abstract

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.

URL<Go to ISI>://000291432700008
DOI10.1103/PhysRevB.83.214511
Alternate JournalPhys Rev BPhys Rev B