Drastic improvement of the trapped field homogeneity in a superconducting hollow bulk by the insertion of a high-Jc superconducting cylinder for NMR bulk magnets
Drastic improvement of the trapped field homogeneity in a superconducting hollow bulk by the insertion of a high-Jc superconducting cylinder for NMR bulk magnets
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DOI：
10.1088/0953-2048/28/9/095018
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发表时间：
2015-08
影响因子：
3.6
通讯作者：
H. Fujishiro;Y. Itoh;Y. Yanagi;Takashi Nakamura
中科院分区：
文献类型：
--
作者：
H. Fujishiro;Y. Itoh;Y. Yanagi;Takashi Nakamura
对200 MHz（4.7 T）核磁共振用REBaCuO超导块材磁体的场冷磁化过程进行了三维数值模拟.研究了体中缺陷的位置和大小对空腔中俘获场不均匀性的影响。俘获场的分布随缺陷的位置和大小而变化，通过插入临界电流密度（Jc2）高于大块圆柱体（Jc1）的超导薄圆柱体，可以显著改善俘获场的不均匀性。超导电流主要在插入的薄圆柱的最外表面上流动，以补偿由缺陷引起的不均匀俘获场。插入具有较高Jc2的超导薄圆柱体对于实际实现紧凑的NMR块体磁体是显著有效的。
Three-dimensional (3D) numerical simulation has been performed for the field-cooled magnetization (FCM) process of REBaCuO superconducting bulk cylinders applicable to the bulk magnet for a 200 MHz (4.7 T) nuclear magnetic resonance (NMR). The influence of the position and size of the defect in the bulk on the inhomogeneity of the trapped field in the hollow space has been investigated. The trapped field profile changes depending on the position and the size of the defect, and the inhomogeneity of the trapped field can be drastically improved by inserting a superconducting thin cylinder with a critical current density (Jc2) higher than that of the bulk cylinder (Jc1). The superconducting current flows mainly on the outermost surface of the inserted thin cylinder to compensate for the inhomogeneous trapped field caused by the defect. The insertion of the superconducting thin cylinder with a higher Jc2 is significantly effective for the practical realization of a compact NMR bulk magnet.