大口径高均匀度核磁共振Halbach磁体研究

doi:10.11938/cjmr20263205

波谱学杂志 ›› 2026, Vol. 43 ›› Issue (3): 253-267.doi: 10.11938/cjmr20263205cstr: 32225.14.cjmr20263205

大口径高均匀度核磁共振Halbach磁体研究

刘万震¹^,², 陈方¹^,², 陈黎¹, 王佳鑫¹, 程鑫¹^,², 易鹏¹, 张志¹^,²^,^*(), 刘朝阳¹^,²^,^#()

¹ 中国科学院精密测量科学与技术创新研究院，磁共振波谱与成像全国重点实验室，武汉磁共振中心，湖北武汉 430071
² 中国科学院大学，北京 100049

收稿日期:2026-02-05 出版日期:2026-09-05 在线发表日期:2026-08-11
通讯作者: 张志,*Tel: 027-87199686, E-mail: zhangzhi@apm.ac.cn;刘朝阳# Tel: 027-87198790, E-mail: chyliu@apm.ac.cn.
基金资助:
国家自然科学基金(22574167);国家自然科学基金(22374158);国家自然科学基金(22404165);国家自然科学基金(22127801);国家自然科学基金(22327901);国家重点研发计划(2022YFF0707000);国家重点研发计划(2023YFE0113300);中国科学院基础与交叉前沿科研先导专项(XDB0540300)

Research on Large-bore and High Homogeneity Halbach Magnet for Nuclear Magnetic Resonance

LIU Wanzhen¹^,², CHEN Fang¹^,², CHEN Li¹, WANG Jiaxin¹, CHENG Xin¹^,², YI Peng¹, ZHANG Zhi¹^,²^,^*(), LIU Chaoyang¹^,²^,^#()

¹ State Key Laboratory of Magnetic Resonance Spectroscopy and Imaging, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
² University of Chinese Academy of Sciences, Beijing 100049, China

Received:2026-02-05 Published:2026-09-05 Online:2026-08-11
Contact: ZHANG Zhi,*Tel: 027-87199686, E-mail: zhangzhi@apm.ac.cn; LIU Chaoyang，# Tel: 027-87198790, E-mail: chyliu@apm.ac.cn.

摘要/Abstract

摘要：

Halbach永磁体因其无需轭铁、外杂散场小等优势，在低场核磁共振（LF-NMR）领域（例如岩芯分析）有着潜在的广泛应用前景．相较于小体积岩芯，大体积更容易保留原始内部结构与流体状态，但其测试时要求更大的磁场均匀区域．然而Halbach磁体的异型结构导致其初始磁场均匀度差，难以直接获得较大的磁场均匀区域．为此，本文结合Halbach磁体理论与有限元仿真方法，设计得到场强158.4 mT、均匀度22 502 ppm（1 ppm=10^-6，直径100 mm球形区域）的Halbach磁体．采用改进的谐波分析无源匀场法，将磁场均匀度提升至1 496 ppm（提升15倍）．无源匀场后采集直径100 mm、高度100 mm硫酸铜水溶液中¹H的FID，并采集双组分硫酸铜溶液CPMG信号，以T₂为依据分辨不同样品组分．上述结果表明，本文的磁体设计方案与无源匀场方法为大口径高均匀度Halbach磁体的构建提供了有效技术支持．

关键词: 核磁共振, Halbach磁体, 磁体设计, 无源匀场, 磁场均匀度

Abstract:

Halbach permanent magnets hold significant promise for low-field nuclear magnetic resonance (LF-NMR) applications, such as rock core analysis, owing to their yoke-free design and low external stray fields. Compared with small rock cores, large rock cores better preserve the original internal structure and fluid distribution, yet they demand a larger homogeneous region. However, the complex structure of Halbach magnets inherently yields inadequate initial homogeneity, making it difficult to directly obtain a sufficiently large homogeneous region. In this study, we defined a 100-mm-diameter spherical region of interest (ROI) and optimized the magnet structure using Halbach magnet theory and finite-element simulations. The final designed magnet provides a field strength of 158.4 mT and an initial homogeneity of 22 502 ppm (1 ppm=10^-6). We applied an improved harmonic-based passive shimming method and enhanced the field homogeneity to 1 496 ppm. After passive shimming, we acquired ¹H free induction decay (FID) signals from an aqueous CuSO₄ sample (Φ 100 mm × H 100 mm), and Carr-Purcell-Meiboom-Gill (CPMG) signals from a two-component CuSO₄ aqueous solution, and distinguished different samples based on their T₂. These results demonstrate that the proposed magnet design and passive shimming method are effective for constructing large-bore, high homogeneity Halbach magnets.

Key words: NMR, Halbach magnet, magnet design, passive shimming, magnetic field homogeneity

中图分类号:

O482.53

刘万震, 陈方, 陈黎, 王佳鑫, 程鑫, 易鹏, 张志, 刘朝阳. 大口径高均匀度核磁共振Halbach磁体研究[J]. 波谱学杂志, 2026, 43(3): 253-267.

LIU Wanzhen, CHEN Fang, CHEN Li, WANG Jiaxin, CHENG Xin, YI Peng, ZHANG Zhi, LIU Chaoyang. Research on Large-bore and High Homogeneity Halbach Magnet for Nuclear Magnetic Resonance[J]. Chinese Journal of Magnetic Resonance, 2026, 43(3): 253-267.

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测试系统部件	部件核心指标	性能参数
谱仪控制子系统	激发频率范围	1~100 MHz
	最小脉冲宽度	150 ns
	最大接收带宽	1 MHz
射频功率放大器	工作频段	6~220 MHz
射频功率放大器	最大输出功率	300 W
前置放大器	工作频段	5~100 MHz
前置放大器	6.79 MHz频点放大倍数	25 dB
25 mm内径射频线圈	调谐频率	6.791 MHz
	回波损耗（S11）	-26.73 dB
	品质因子（Q值）	75.3
100 mm内径射频线圈	调谐频率	6.792 MHz
	回波损耗（S11）	-40.01 dB
	品质因子（Q值）	26.3

大口径高均匀度核磁共振Halbach磁体研究

Research on Large-bore and High Homogeneity Halbach Magnet for Nuclear Magnetic Resonance

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