The Influence of the Magnetic Field on the Dynamics of the Flux Jumps in the Flux Flow Model

Abstract

We studied the dynamics of the flux jumps in type II superconductors assuming this dynamics to be determined by magnetic diffusion. The conductivity of the sample during the jump was described by the flux flow conductivity, which depends on local magnetic field. We solved this problem numerically for an infinite slab sample. We assumed that superconducting sample was fully penetrated by the magnetic flux at the beginning and that the local induction of the magnetic field, in the whole sample, was equal to B 0 . Then, the external magnetic field was increased by a value of ∆B a and in the external magnetic field of B 0 + ∆B a flux jump occurred. In our simulations we used the parameters characteristic of a conventional NbTi superconductor at 4.2 K. In particular, we studied the influence of the parameter B 0 on the flux jumps' dynamics. We have found that this parameter strongly influences initial stage of the diffusion process. With increasing B 0 , the time during which flux front of the avalanche reaches the center of the sample decreases. The results of numerical simulations were compared with experiments.