Abstract
This paper analyses the role of defects within the flux-line lattice of high-current-density superconductors. A simple model demonstrates that above the normal density distribution in critical currents the E-J characteristics is linear with a resistivity many orders of magnitude less than the bulk flux-flow resistivity. The universality of the three free parameters that describe the defect motion is explicitly demonstrated by considering data on Nb3Sn throughout its entire superconducting phase.