The process of magnetic flux penetration into superconductors

In the present paper the magnetic flux penetration dynamics of type-II superconductors in the flux creep regime is studied by analytically solving the nonlinear diffusion equation for the magnetic flux induction, assuming that an applied field parallel to the surface of the sample and using a power-law dependence of the differential resistivity on the magnetic field induction. An exact solution of nonlinear diffusion equation for the magnetic induction B(r, t) is obtained by using a well-known self-similar technique. We study the problem in the framework of a macroscopic approach, in which all length scales are larger than the flux-line spacing; thus, the superconductor is considered as a uniform medium.

Динамические вихревые состояния в высокотемпературных сверхпроводниках при импульсном намагничивании

By using the Monte Carlo method, numerical modeling of the vortex system of a Bi-2212 superconductor in a ramping external magnetic field has been carried out for different ramp-rates. The influence of concentration and distribution of pinning centers on the magnetic flux penetration has been studied. Features of flux penetration have been observed and described in terms of the vortex system dynamics, the conditions for their occurrence have been determined. Ascending dependences of the saturation field on defect concentration have been obtained for homogeneous and inhomogeneous samples.