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单边核磁共振Halbach磁体结构设计

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作者:杜海龙1, 王琦1, 周振宇2, 蒋川东2

作者单位: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


关键词:核磁共振仪器;Halbach磁体;有限元方法;参数优化


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0.5 m×0.095 m×0.095 m、磁体结构半径为0.63 m,在50 cm×50 cm区域得到中心场强为0.020 9 T,不均匀度为3.085×10-4,梯度为0.739 mT/cm的磁场。


The structural design method of Halbach magnets for unilateral nuclear magnetic resonance
DU Hailong1, WANG Qi1, ZHOU Zhenyu2, JIANG Chuandong2
1. College of Communication Engineering, Jilin University, Changchun, 130012, China;
2. College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130026, China
Abstract: 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.
Keywords: nuclear magnetic resonance instrument;Halbach magnet;finite element method;parameter optimization
2019, 45(6):96-100  收稿日期: 2018-10-29;收到修改稿日期: 2018-12-03
基金项目: 国家自然科学基金资助项目(41604083,41704103)
作者简介: 杜海龙(1983-),男,吉林长春市人,工程师,主要从事仪器与检测方法研究
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