Analysis of critical current inhomogeneity in r–z plane of GdBCO superconducting bulk and simulation of flux jumps during pulsed field magnetization

Abstract

In pulsed field magnetization (PFM), the phenomenon of flux jump is capable of driving magnetic flux vortexes into the GdBCO superconducting bulk center to aid full magnetization. Various homogeneous critical current density (J c) models have been implemented to reproduce flux jumps, but the simulated multi-physical responses differ from experimental observations. This paper proposes a modified J c model to consider r–z plane J c inhomogeneity, and simulates flux jumps under experimental conditions by solving a 2D axisymmetric electromagnetic-thermal coupled model. A numerical treatment is developed to reflect the breaking of shielding current during flux jumps. The accuracy of our model is verified by comparisons of the calculated results for trapped magnetic fields (B T) and the PFM and field-cooling experimental results. On this basis, we investigate the improvement of the inhomogeneous J c model and obtain multi-physical responses that show better agreement with the experimental results compared to the homogeneous J c model. Moreover, to further test the ability of the inhomogeneous J c model to predict the anisotropy of the spatial magnetic field distribution, the simulated B T profiles at the top and bottom surfaces of the high-temperature superconductor (HTS) bulk at 77 K are compared to the experiments. This study may provide a new approach for modeling the inhomogeneity of J c characteristics and a useful analysis tool for industrial devices using HTS bulk magnets.