Design and Optimization of Multilayer Cylindrical Magnetic Shield for SERF Atomic Magnetometer Application

摘要

A set of five-layer cylindrical magnetic shields is designed and constructed to attenuate external geomagnetic field to less than 10 nT (ideally zero). We aim to achieve a shield design having high shielding factor, low magnetic noise, and small volume. However, magnetic noise is incompatible with shielding factor and volume. Thus, there is a compromise. This paper presents an optimization method to acquire a sufficiently effective, low-noise, and lightweight multi-layer shield. The optimization objective and constraints are provided in the form of analytic expressions. The mathematical model is constructed in MATLAB. The optimization is executed in iSIGHT software integrated MATLAB. By optimizing the nonlinear programming quadratic line (NLPQL) algorithm, theoretically the axial shielding factor S-tot(A) can be increased by a factor of about 390.3, on the premise that the magnetic noise and volume have increased negligibly. Apart from better shielding performance, a combination of optimum parameters is obtained. This optimization method has good universality. As long as certain shielding requirements are determined, the corresponding optimum parameters can be acquired accurately. This method is of great significance for future improvements to shield design.