Study of Magnetic Noise of a Multi-Annular Ferrite Shield

IEEE Access

Bozheng Xing¹  Wei Quan¹  Junpeng Zhao¹  Bangcheng Han¹  Ming Ding¹  Jixi Lu¹  Danyue Ma¹  Ke Yang¹ 

[1] Research Institute for Frontier Science, Beihang University, Beijing, China;

关键词: Ferrite;    magnetic shield;    magnetic noise;    atomic magnetometer;   

DOI  :  10.1109/ACCESS.2020.2976785

来源: DOAJ

【 摘 要 】

Ferrites are promising nonmetallic materials used for the fabrication of low-noise magnetic shields because they possess high permeability and high electrical resistivity. However, large-sized ferrite components are difficult to fabricate or machine. In this study, we develop a cylindrical ferrite shield that consists of five annuli and two lids with an inner volume of φ11.2 cm × 22.5 cm. Although this structure contains gaps between different components, it eases considerably the fabrication and machining process as compared to the entire module. The magnetic noise is measured by a spin-exchange relaxation-free atomic magnetometer, and the detrimental effects of the gaps are analyzed quantificationally using the finite element method. Our research results indicate that compared with the ferrite shield without gaps, the magnetization noise increases by 34.1%. Nonetheless, the magnetic noise at the center of the ferrite shield achieves 5.5f -1/2 fT, which is much lower than that of μ-metal shields with a similar size. If the gap width can be reduced to be smaller than 0.01 mm, the increase of the magnetization noise will be less than 4.9%, which can be negligible in practical applications. Our study provides a low-cost, readily available, and low-noise ferrite shield structure.

【 授权许可】

Unknown