Modeling and Analysis of Magnetic Noise in Nanocrystalline Spindle-Shaped Magnetic Shielding System

The magnetic shielding system (MSS) composed of permalloy and nanocrystalline provides a near-zero magnetic field and low magnetic noise (MN) environment for SERF magnetic field measurement devices. Accurate calculation and analysis of the MN in MSS is crucial for achieving high sensitivity. Existing nanocrystalline MN calculation methods mainly apply to cubic and cylindrical structures with uniaxial anisotropy and are unsuitable for irregularly shaped magnetic shields with arbitrary anisotropy. The spindle-shaped magnetic shielding cylinder (sMSC) offers superior shielding performance and lower MN. In this study, a novel MN model for the MSS is proposed, which accounts for the changes in the intrinsic MN of the nanocrystalline caused by the variations in electromagnetic parameters due to the irregular shape of the nanocrystalline sMSC. The model also considers the environmental MN. The MN calculation from the proposed model shows a 5.71% error compared to experimental data, verifying the model’s accuracy. Furthermore, this study analyzes the variation of remanence and MN with the spatial position in the nanocrystalline sMSC and the effects of thickness and volume on the MN. This study offers theoretical support to significantly improve the performance of SERF sensors.