Design of Biplanar Nested Square Uniform Coil in Lightweight Magnetically Shielded Room for Magnetocardiography System
Xiaoxuan Xie, Xiangyang Zhou, Fengwen Zhao, Weiqian Wang, Jinji Sun
Abstract
This paper proposed a new method for biplanar nested square uniform coil (BNSUC) in magnetically shielded room (MSR), which effectively solves the uniformity distorted by the coupling effect between coil and MSR. Firstly, based on the image method (IM), this paper innovatively considers the coupling between the ferromagnetic material and the coils, and gives the analytical expression for the space magnetic field of the inner BNSUC for the first time; Secondly, a method combining the Taylor expansion method and the target point method is proposed to enlarge the uniform area of the coil; Finally, the parameter structure of the optimal BNSUC suitable for lightweight MSR is obtained through the particle swarm optimization of the multi-level inertial weight (MW-PSO) algorithm. The experimental show that the area that ε ≤ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> of the designed BNSUC is 54.29%, which is 32 times higher than original coil. Besides, combined with closed-loop technology, the magnetic field fluctuation inside MSR is reduced by one time and the long-term stability of the field is guaranteed. As high uniformity and simple structure, the method is of great significance for magnetocardiography (MCG) in lightweight MSR.