A trapped field of B T = 1.61 T was experimentally achieved at the central surface of an MgB2 bulk composite (60 mm in diameter and 20 mm in height) at 20 K by double pulsed-field magnetization (PFM) using a split-type coil. The composite bulks consisted of two MgB2 ring bulks sandwiched by thin copper ring plates, which were then stacked, and a soft iron yoke cylinder was inserted in the central bore of the rings. The copper ring plates delayed the rise time and duration of the magnetic pulse due to eddy currents. The inserted soft iron yoke attracted the magnetic flux and enhanced the trapped field strength mainly due to its large permeability. As a result, the trapped field was enhanced from B T = 0.34 T for the single MgB2 ring bulk without the copper plates and soft iron yoke to B T = 1.00 T for the composite with both copper plates and the soft iron yoke. The inserted soft iron yoke can be exploited to enhance the trapped field because the intrinsic B T of the single MgB2 ring bulk was smaller than the saturation field of the yoke (~2 T). Using an optimized second pulse application after suitable flux trapping from the first pulse application, the trapped field was enhanced considerably to B T(2nd) = 1.61 T, which is a record-high trapped field for an MgB2 bulk by PFM to date. The combination of the elongation of the magnetic pulse by the copper plates, the enhancement of the effective applied field due to the inserted soft iron yoke, and the second pulse application using split-type coil is an effective technique to enhance the trapped field in the MgB2 bulk using PFM.

中文翻译：

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由铜板和软铁轭圆柱体组成的MgB ₂块体中 1.61 T 的创纪录高俘获场使用脉冲场磁化

BT = 1.61 T 的俘获场是在 20 K 的 MgB2 块状复合材料（直径 60 毫米，高度 20 毫米）的中心表面通过使用分裂式线圈的双脉冲场磁化 (PFM) 实验实现的。复合块体由两个 MgB2 环块体组成，中间夹着薄铜环板，然后堆叠在一起，并将软铁轭圆柱体插入环的中心孔中。由于涡流，铜环板延迟了磁脉冲的上升时间和持续时间。插入的软铁轭主要由于其大的磁导率而吸引磁通量并增强了俘获场强度。结果，没有铜板和软铁轭的单个 MgB2 环体的俘获场从 BT = 0.34 T 增强到 BT = 1。00 T 为复合铜板和软铁轭。插入的软铁轭可用于增强俘获场，因为单个 MgB2 环体的本征 BT 小于轭的饱和场（~2 T）。在第一次脉冲施加合适的通量捕获后使用优化的第二次脉冲应用，捕获场显着增强至 BT(2nd) = 1.61 T，这是迄今为止 PFM 对 MgB2 块体的记录高捕获场。铜板延长磁脉冲、插入软铁轭增强有效外加场以及使用分体式线圈的二次脉冲相结合，是一种有效的技术，可以增强磁体中的俘获场。使用 PFM 的 MgB2 块体。插入的软铁轭可用于增强俘获场，因为单个 MgB2 环体的本征 BT 小于轭的饱和场（~2 T）。在第一次脉冲施加合适的通量捕获后使用优化的第二次脉冲应用，捕获场显着增强至 BT(2nd) = 1.61 T，这是迄今为止 PFM 对 MgB2 块体的记录高捕获场。铜板延长磁脉冲、插入软铁轭增强有效外加场以及使用分体式线圈的二次脉冲相结合，是一种有效的技术，可以增强磁体中的俘获场。使用 PFM 的 MgB2 块体。插入的软铁轭可用于增强俘获场，因为单个 MgB2 环体的本征 BT 小于轭的饱和场（~2 T）。在第一次脉冲施加合适的通量捕获后使用优化的第二次脉冲应用，捕获场显着增强至 BT(2nd) = 1.61 T，这是迄今为止 PFM 对 MgB2 块体的记录高捕获场。铜板对磁脉冲的延长、由于插入的软铁轭增强了有效外加场以及使用分体式线圈的第二次脉冲外加的组合，是一种有效的技术，可以增强被困磁场中的俘获场。使用 PFM 的 MgB2 块体。