Influence of Radiation Induced Nano-defects on Critical Current of HTc Superconductors

Abstract

Superconductors, including HTc materials are more and more frequently used in modern nuclear physics devices. During the work of nuclear accelerators arises however the radiation of heavy ions or fast neutrons, which can reach the superconducting windings, creating nano-sized defects. It influences properties of superconductors. In the paper is given theoretical analysis of the influence of nano-defects on the critical current of HTc superconductors. New theoretical model of the critical current is proposed based on an analysis of the interaction of nano-defects acting as pinning centers with pancake vortices appearing in HTc superconductors. Nano-defects from one side destroy the structure of superconducting materials, which effect has negative meaning, while from other side anchorage of individual vortices or vortex lattice on defects will improve critical current. These both opposite phenomena are considered for HTc materials and also for A15 type superconductors, in which superconductivity is strongly related to state of ordering of transition metals as Nb, V in linear chains. The potential barrier against pancake vortices movement has been considered and calculations of an influence of sizes of nano-defects on current-voltage characteristics performed. Expression for an energy barrier allowed also to determine the time stability of the magnetic vortex structure and flowing current, which effect has especial meaning in the superconducting shields. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35418