Design and implementation of a high-performance miniaturized multi-layer magnetic shielding spherical shell with minimal pores based on target magnetic field

Achieving the spin-exchange relaxation-free (SERF) state in atomic comagnetometers (ACMs) necessitates a stable and weak magnetic environment. This paper presents the design of a miniaturized permalloy magnetic shielding spherical shell (MSSS) with minimal apertures, tailored to meet these requirements. By employing a combination of analytical solutions and finite element analysis (FEA), we achieved superior magnetic shielding while maintaining a compact form factor. The analytical solution for the shielding factor indicated that a four-layer permalloy sphere shell with optimized air gaps was necessary. A numerical analysis model of the MSSS was developed and validated using COMSOL software, confirming the suitability of the air gaps. The size, shape, and orientation of the openings in the perforated sphere shell were meticulously designed and optimized to minimize residual magnetism. The optimal structure was fabricated, resulting in triaxial shielding factors of 47619, 52631, and 21739, meeting the anticipated requirements. A comparison of simulation results with experimental tests demonstrated the efficacy of the design methodology. This study has significant implications for ultra-sensitive magnetic field detection devices requiring weak magnetic field environments, such as atomic gyroscopes, magnetometers, atomic interferometers, and atomic clocks.