研究論文
超電導薄層円筒内挿によるNMR 用超電導バルクの捕捉磁場均一化の シミュレーション解析
― 円筒の位置，長さ，形状の影響 ―
2017 年 52 巻 1 号 p. 33-37
詳細
2017 年 52 巻 1 号 p. 33-37
The effect of inserting high-Jc HTS thin cylinders into a 200 MHz (4.7 T) nuclear magnetic resonance (NMR) superconducting bulk magnet using a field-cooled magnetization (FCM) process and three-dimensional (3D) numerical simulation was studied. High-Jc thin cylinders of various lengths and shapes were inserted in various positions. A recent experiment in which a cylinder wrapped with a high-Jc material was inserted in a bulk cylinder was confirmed to be effective in reducing the inhomogeneity of the trapped field in the hollow space. We also modeled an actual cylinder with several kinds of slits. As a result of the defect in the NMR cylinder bulk magnet, the inhomogeneity of the trapped field can be drastically improved by inserting a HTS thin cylinder that has a higher Jc than a bulk material the same length as the bulk magnet. However, the level of improvement in the trapped field homogeneity changes depending on the spatial relationship between the defect and the HTS thin cylinder, and on the length and shape of the HTS thin cylinder with and without slits. The superconducting current flows in the HTS thin cylinder to compensate for the inhomogeneous trapped field caused by the defect. The optimum length and shape of the high-Jc HTS thin cylinder is discussed in terms of realizing a practical compact NMR bulk magnet.
