Simulation Research on Low-Frequency Magnetic Noise in Fe-Based Nanocrystalline Magnetic Shields

Depending on high permeability, high Curie temperature, and low eddy current loss noise, nanocrystalline alloys, as the innermost layer, exhibit great potential in the construction of cylindrical magnetic shielding systems with a high shielding coefficient and low magnetic noise. This study compares a magnetic noise of 1 Hz, simulated by the finite element method (FEM), of a cylindrical nanocrystalline magnetic shield with different structural parameters based on the measured initial permeability of commercial Fe-based nanocrystalline (1K107). The simulated results demonstrate that the magnetic noise is irrelevant to the pump and probe hole diameter. The magnetic noise of a nanocrystalline cylinder with a fixed length gradually increases with the rise in aspect ratio. The radial and axial magnetic noise of a nanocrystalline cylinder with a fixed diameter can reach optimal values when the aspect ratio is 1.3 and 1.4, respectively. The layer thickness of a nanocrystalline cylinder is negatively correlated to magnetic noise. Additionally, by comparing the 1 Hz magnetic noise of a cylindrical nanocrystalline magnetic shield with varying initial permeability, it can be concluded that an increase in loss factor results in an increase in magnetic noise. These results are useful for the design of a high-performance passive magnetic shield with low magnetic noise.