Comprehensive Analysis and Structural Optimization for Single-Ended Open Magnetic Shielding Cylinder

Evaluating and enhancing the alternating current (ac) shielding performance of magnetic shielding cylinders (MSCs) is important to improve the sensitivity of magnetometers and the signal-to-noise ratio (SNR) of magnetocardiography (MCG). The dynamic radial shielding factor (RSF) of single-ended open MSC rapidly decreases with increasing frequency. To accurately analyze and improve the dynamic RSF, a high-performance and low-cost permalloy-nanocrystalline MSC (P-N-MSC) composite structure is innovatively proposed based on the analytical and finite element model (FEM) in this article. The structural reason why placing nanocrystals in the innermost layer of P-N-MSC performs significantly better than placing nanocrystals in the middle and outer layers is analyzed in detail through experiments and finite element simulations. The average dynamic RSF of P-N-MSC is 2.05 times higher than that of MSC among 0.5-95 Hz. The average noise at 0.5-95 Hz is reduced by 63.58%. This study provides a theoretical basis and technical support for constructing magnetic shielding devices with high magnetic shielding performance.