Analysis of Passive Shielding Performance Stability in Hybrid Magnetic Shielding Devices

In hybrid active–passive magnetic shielding systems, active compensation coils are used to suppress residual magnetic fields inside the shield. However, due to the intrinsic hysteresis of high-permeability materials, the compensation fields inevitably magnetize the passive layers. This process introduces new and unpredictable remanent magnetization, paradoxically worsening the remanence stability during active compensation. This study systematically investigates and quantifies how the number of passive shielding layers affects remanence instability. A combined approach of theoretical analysis, finite-element simulations, and experimental validation is employed. The results reveal a key counter-intuitive finding: although adding more shielding layers enhances the static attenuation of external fields, it markedly amplifies the remanence instability induced by active compensation. Specifically, multi-layer shields exhibit larger remanence changes under identical compensation-field excitations. This finding reveals a previously overlooked performance trade-off and provides new design insights for ultra-high-precision shielding systems. These findings provide essential guidance for optimizing the design and operation of next-generation ultra-high-precision magnetic shielding devices and their applications in frontier areas such as fundamental physics and biomedicine.