单边核磁共振Halbach磁体结构设计  

The structural design method of Halbach magnets for unilateral nuclear magnetic resonance

作　　者：杜海龙[1] 王琦[1] 周振宇 蒋川东[2] DU Hailong;WANG Qi;ZHOU Zhenyu;JIANG Chuandong(College of Communication Engineering,Jilin University,Changchun,130012,China;College of Instrumentation and Electrical Engineering,Jilin University,Changchun 130026,China)

机构地区：[1]吉林大学通信工程学院,吉林长春130012 [2]吉林大学仪器科学与电气工程学院,吉林长春130026

出　　处：《中国测试》2019年第6期96-100,共5页China Measurement & Test

基　　金：国家自然科学基金资助项目(41604083,41704103)

摘　　要：传统核磁共振仪器多采用封闭式磁体结构,导致仪器开放性和便携性差,制约其应用范围。为解决上述问题,该文基于电磁场理论,利用二阶有限元方法,研究半环形Halbach磁体的结构设计方法,分析磁块几何结构和尺寸等参数对Halbach磁体产生的中心场强、横向均匀度和纵向梯度的影响。验证该磁体结构无需增加线圈,即可产生核磁共振实验所需的横向均匀纵向梯度分布的磁场。优化后的单边Halbach磁体结构为:磁块尺寸为0.5m×0.095m×0.095m、磁体结构半径为0.63m,在50cm×50cm区域得到中心场强为0.0209T,不均匀度为3.085×10^-4,梯度为0.739mT/cm的磁场。Closed magnet structure is usually applied to traditional nuclear magnetic resonance instruments use, resulting in poor openness and portability. To solve the problems, the structural design method of semi-annular Halbach magnets is studied in this paper. Based on the second-order finite element method, the effects of parameters such as magnetic block geometry and magnetic block size on the center field strength, lateral uniformity and longi-tudinal gradient of the magnetic field generated by the Halbach magnet are analyzed. It is verified that the magnet structure can generate a magnetic field with a laterally uniform longitudinal gradient distribution without the need to add gradient coils. The optimization results show that the semi-annular Halbach magnet with a magnetic block size of 0.5 m×0.095 m×0.095 m and a structure radius of 0.63 m can produce a magnetic field with a center field strength of 0.020 9 T, a nonuniformity of 3.085×10^-4, and a gradient of 0.739 mT/cm in a region of interest area of 50 cm×50 cm.

关 键 词：核磁共振仪器 HALBACH磁体 有限元方法 参数优化 

分 类 号：TM153[电气工程—电工理论与新技术]