Magnetic history effects on DC shielding performance of Bi-2223 and Bi-2223/Fe coaxial cups

The DC magnetic shielding properties of a commercial Pb-doped Bi (Formula presented) (Formula presented) Sr (Formula presented) (Formula presented) Ca (Formula presented) (Formula presented) Cu (Formula presented) (Formula presented) O (Formula presented) (Formula presented) (Bi-2223) cup were investigated under axial, transverse, and crossed magnetic field configurations. Particular attention was devoted to the role of the magnetization history, which was shown to significantly influence the ability to shield a magnetic field applied orthogonal to the direction of the first magnetization process. A progressive reduction of the shielding capability was observed with increasing field applied in the pre-magnetization process, revealing distinct regimes associated with the evolution of the internal current distribution. The superimposition of a ferromagnetic (FM) cup was found not only to strongly increase the maximum shielded field—from 8.2 to 144 mT in the transverse orientation and from 11.5 to 68 mT in the axial orientation—but also to markedly reduce these history dependent effects, leading to a more stable shielding performance over a wide range of pre-magnetization field values. To understand these results, a three-dimensional numerical approach based on the vector potential (A) formulation was developed and validated by comparing the computational output with the experimental data. The simulations provide insight into the underlying mechanisms, highlighting the competition between magnetization-induced and shielding currents and their impact on the final current density distribution. These findings clarify the role of magnetization history in Bi-2223 magnetic shielding and demonstrate the effectiveness of hybrid superconducting/FM configurations for improving performance under realistic operating conditions.