Advanced field shimming technology to reduce the influence of a screening current in a REBCO coil for a high-resolution NMR magnet
Advanced field shimming technology to reduce the influence of a screening current in a REBCO coil for a high-resolution NMR magnet
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DOI：
10.1088/0953-2048/29/4/045013
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发表时间：
2016-04-01
影响因子：
3.6
通讯作者：
Yanagisawa, Y.
中科院分区：
文献类型：
--
作者：
Iguchi, S.;Piao, R.;Yanagisawa, Y.
本文描述了一种场匀场技术，用于在（RE）Ba₂Cu₃O₇₋ₓ（REBCO）线圈中的屏蔽电流影响下，获得高分辨率核磁共振（NMR）磁体所需的空间均匀磁场。使用REBCO内线圈是实现超高场（>23.5 T，1 GHz）NMR磁体的一种解决方案。然而，由于薄带导体引入的不均匀线圈绕组，REBCO线圈会产生大量的场误差谐波。此外，由于REBCO线圈中屏蔽电流的屏蔽效应，场校正线圈和外部超导（SC）匀场线圈的性能显著降低。因此，使用SC匀场线圈和室温匀场线圈的常规匀场技术无法充分补偿这些场误差谐波，也就无法进行高分辨率的NMR测量。在本文中，一种先进的场匀场技术，包括一个内部SC匀场线圈和一种新型铁磁匀场体，被安装在一个400 MHz低温SC/REBCO NMR磁体中。内部SC匀场线圈和铁磁匀场体分别补偿了场校正线圈和SC匀场线圈性能的降低。利用该技术，场误差谐波得到了极大的补偿，并且实现了高NMR分辨率。
This paper describes a field shimming technology to obtain a spatially homogeneous magnetic field required for a high-resolution nuclear magnetic resonance (NMR) magnet under the influence of a screening current in a (RE) Ba2Cu3O7-x (REBCO) coil. Use of REBCO inner coils is one solution to realize a super-high field (>23.5 T, 1 GHz) NMR magnet. However, a REBCO coil generates a large amount of field error harmonics due to the inhomogeneous coil winding introduced by a thin tape conductor. In addition, the performance of a field correction coil and outer superconducting (SC) shim coils are significantly reduced due to the shielding effect of the screening current in the REBCO coil. Therefore, conventional shimming technology using SC shim coils and room temperature shim coils cannot adequately compensate those field error harmonics and high-resolution NMR measurements are not possible. In the present paper, an advanced field shimming technology including an inner SC shim coil and a novel type of ferromagnetic shim were installed in a 400 MHz low-temperature SC/REBCO NMR magnet. The inner SC shim coil and the ferromagnetic shim compensated for the reduction in the performances of the field correction coil and the SC shim coils, respectively. The field error harmonics were greatly compensated with the technology and a high NMR resolution