Magnetization Measurement Methods of Magnetic Shielding Devices and Analysis of Correlations With Spatial Magnetic Noise

The magnetic shielding devices (MSDs) play a crucial role in magnetoencephalography (MEG) measurements by providing a near-zero magnetic environment with low magnetic noise (MN), enabling the detection of extremely weak neural signals. However, MN within MSDs typically exhibits complex spatial nonuniformity, which closely relates to the magnetization distribution within the shielding materials. Traditional measurement and modeling approaches often fail to accurately reveal this correlation. This study proposes a magnetization inversion theoretical model based on magnetic flux density (MFD). By precisely measuring the MFD, the spatial magnetization distribution is reconstructed. A correlation analysis model between magnetization and MN is then established. Normalizing MN and magnetization at different spatial locations yields a correlation coefficient exceeding 0.96, validating the linear relationship between MN and magnetization distribution. This study elucidates the mechanism of MN generation and offers a novel technological pathway for optimizing MN suppression in ultrahigh-sensitivity atomic sensors.