Park Dongkeun, Lee Jiho, Bascuñán Juan, Li Zhuyong, Iwasa Yukikazu
Francis Bitter Magnet Laboratory/Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Institute for Basic Science, Daejeon, 34126, South Korea.
Sci Rep. 2020 Dec 15;10(1):21946. doi: 10.1038/s41598-020-78644-0.
We present promising results of novel high-temperature superconducting (HTS) shim coil prototypes that circumvent the size and strength limitation of our earlier innovative HTS shim concept based on 46-mm wide REBCO tape. The HTS shim coil is placed inside the HTS magnet, mainly for ultra-high-field (> 1 GHz or 23.5 T) NMR magnets, and thus unaffected from the windings' diamagnetic wall effects. One full-scale version will be applied to clean up Z1 and Z2 harmonic errors in the MIT 1.3-GHz high-resolution NMR magnet composed of an 835-MHz HTS insert, while another version for an MIT 1-GHz microcoil NMR magnet whose small-scale model we are currently building. The prototype sets were wound with a 2-pile, 1.03-mm wide, 0.30-mm thick REBCO conductor. Operated at 77 K, the Z1 shim set generated a 1st harmonic field strength of 179 kHz/cm at 70 A, while the Z2 shim set, composed of two pairs, Z2 and Z2, generated the 2nd harmonic field of 141 kHz/cm at 50 A. Together with discussion on technical challenges for this REBCO shim coil concept, we demonstrate its feasibility for the next generation of ultra-high-field (UHF) HTS NMR magnets.
我们展示了新型高温超导（HTS）匀场线圈原型的良好结果，该原型克服了我们早期基于46毫米宽REBCO带材的创新HTS匀场概念在尺寸和强度方面的限制。HTS匀场线圈放置在HTS磁体内部，主要用于超高场（>1 GHz或23.5 T）的核磁共振磁体，因此不受绕组抗磁壁效应的影响。一个全尺寸版本将应用于清理麻省理工学院1.3 GHz高分辨率核磁共振磁体（由一个835 MHz的HTS插入件组成）中的Z1和Z2谐波误差，而另一个版本用于麻省理工学院1 GHz微线圈核磁共振磁体，我们目前正在制作其小规模模型。原型组采用2股、1.03毫米宽、0.30毫米厚的REBCO导体绕制而成。在77 K下运行时，Z1匀场组在70 A时产生的一次谐波场强为179 kHz/cm，而由两对Z2组成的Z2匀场组在50 A时产生的二次谐波场为141 kHz/cm。在讨论这种REBCO匀场线圈概念所面临的技术挑战的同时，我们证明了其在下一代超高场（UHF）HTS核磁共振磁体中的可行性。
