Self-Shielded Uniform Magnetic Field Coil Design for Miniature Atomic Sensors Using a Particle Swarm Optimization Algorithm

Abstract

In this paper, an optimization method that uses the derivatives and the target field information of the magnetic field simultaneously is proposed to suppress the coupling between the coil and the magnetic shielding in miniature atomic sensors. The coupling between the coil and the magnetic shielding varies with the material magnetic permeability, which causes the magnetic field to fluctuate with the temperature as the material permeability. The magnetic field fluctuations will cause the measurement errors and drifts of the sensors. The proposed method can effectively suppress the magnetization of the magnetic shielding caused by the coil magnetic field. A shielded coil outside the main coil is used to efficiently attenuate the magnetic field outside the main coil to suppress the coupling between the coil and the magnetic shielding. A coil system consisting of pairs of circular coils distributed on two coaxial cylinder surfaces is proposed in this paper. The Taylor expansion is used to ensure the uniformity of the internal magnetic field, while the target field information is used to ensure the attenuation of the external magnetic field. A particle swarm optimization (PSO) algorithm is used to optimize the parameters of the main and shielded coils. The theoretical calculations and the finite element analysis prove that the proposed approach is an effective design method for the self-shielded coils.