Optimized analysis of magnetic noise based on residual magnetization measurements of magnetic shielding devices

Magnetic shielding devices (MSDs) provide a low-noise ultra-weak magnetic environment for magnetoencephalography (MEG) measurements. Reducing the residual magnetization (RM) of MSDs is critical for high-sensitivity measurements. Considering the anisotropic properties of laminated nanocrystalline materials, we propose a magnetic noise calculation model that accounts for anisotropy. This paper further introduces an RM measurement method for MSDs based on sensors and finite element models to investigate the effect of RM on magnetic noise. Based on the computed conversion matrix and the magnetic flux density matrix measured by sensors, calculate the RM of the MSD. The magnetic noise and RM at different points are tested and normalized, showing that the RM correlates with the trend of magnetic noise, with decision coefficients greater than 0.99. The central point along the Y-axis of the nanocrystalline magnetic shielding device (NMSD) is selected for magnetic noise simulation and experimentation. The discrepancy between the simulation and experimental results is 3.42 %, validating the effectiveness of the proposed model. This study provides an essential basis for optimizing the magnetic noise of MSDs for ultra-high-sensitivity atomic sensors.