Park Dongkeun, Choi Yoon Hyuck, Iwasa Yukikazu
Francis Bitter Magnet Laboratory / Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
IEEE Trans Appl Supercond. 2019 Aug;29(5). doi: 10.1109/TASC.2019.2898704. Epub 2019 Feb 11.
We present a design study of a liquid-helium (LHe)-free 23.5-T, ϕ25-mm RT-bore REBCO magnet for high-resolution 1-GHz microcoil nuclear magnetic resonance (NMR) spectroscopy. A microcoil NMR magnet is compact and thus its cost will be less by nearly an order of magnitude than that of the standard NMR magnet, and placeable on a bench, thereby resulting in a large saving in space. In addition, LHe-free operation enables the user to be independent from a cooling source in short supply. This paper includes: 1) magnet design and conductor requirement specification; 2) conceptual design of a full-scale tabletop LHe-free 1-GHz NMR magnet; and 3) design of a 10-K operating REBCO 23.5-T magnet prototype with a ϕ20-mm cold-bore. This small-size magnet prototype will be built and tested by 2020 for validation of performance and manufacturing challenges such as splices between coils. The paper concludes with discussion of stray-field shielding methods and a screening-current-inducing field (SCF) effect.
我们展示了一种用于高分辨率1-GHz微线圈核磁共振（NMR）光谱的无液氦（LHe）23.5-T、内径25-mm室温孔径REBCO磁体的设计研究。微线圈NMR磁体结构紧凑，因此其成本将比标准NMR磁体低近一个数量级，并且可以放置在工作台上，从而大幅节省空间。此外，无液氦运行使用户无需依赖供应短缺的冷却源。本文包括：1）磁体设计和导体要求规范；2）全尺寸桌面型无液氦1-GHz NMR磁体的概念设计；3）内径20-mm冷孔的10-K运行REBCO 23.5-T磁体原型的设计。这个小尺寸磁体原型将于2020年制造并测试，以验证性能以及诸如线圈间拼接等制造方面的挑战。本文最后讨论了杂散场屏蔽方法和屏蔽电流感应场（SCF）效应。
