Optimized design of small sized low noise magnetic shielding cylinder

Abstract

Magnetic shielded cylinder (MSC) is crucial in various applications, especially in the realm of medical weak magnetic signal measurement. However, designing a small volume, low noise MSC is a multi-objective optimization problem, with the objectives conflict with each other. To address the complexity arising from numerous variables in the optimal design of MSC with a small volume and low-noise, this paper proposes an optimal design method based on non-dominated sorting genetic algorithm II (NSGA-II) to realize the optimal design of MSC with a high shielding factor, small volume and low-noise. Firstly, an analytical model for the shielding factor of the MSC is established, and a multi-objective optimization model is given. Then, the NSGA-II algorithm is employed to obtain a series of Pareto frontier optimal solutions. Finally, the efficacy of this method is evaluated through simulation and experimentation. The results reveal that the radial and axial shielding factors of the optimized MSC achieve maximum values of 8.6×107 and 9.5×106 respectively. Meanwhile, the average axial noise and radial noise of the MSC between 1 and 100 Hz are 22 fT/Hz1/2 and 20 fT/Hz1/2 respectively. Practice has proven that this method can be used to optimize the design of small-volume, low-noise magnetic shields to improve the performance of magnetic shields.

Design and experiment of high-performance small magnetic shielding box

“…Zero magnetic or weak magnetic environments are commonly provided by magnetic shielding devices. Common magnetic shielding devices mainly include magnetic shielding rooms (MSR) [15,16] and magnetic shielding cylinders (MSC) [17,18], typically utilizing the eddy current effect of high-conductivity materials and magnetic flux diversion of high-permeability materials for shielding. The Berlin magnetically shielded room 2 (BMSR-2) features a magnetic residual field below 500 pT and a field gradient level less than 0.5 pT/mm, which are needed for very sensitive human biomagnetic recordings or low field NMR [19].…”