Guan Mingzhi, Hahn Seungyong, Bascuñán Juan, Wang Xingzhe, Gao Peifeng, Zhou Youhe, Iwasa Yukikazu
Plasma Science and Fusion Center, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
Key Laboratory of Mechanics on Disaster and Environment in Western China, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, China.
IEEE Trans Appl Supercond. 2016 Jun;26(4). doi: 10.1109/tasc.2016.2521679. Epub 2016 Jan 26.
A high-resolution 1.3-GHz/54-mm low-temperature superconducting/high-temperature superconducting (HTS) nuclear magnetic resonance magnet (1.3 G) is currently being built at Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology. One of its key components is an 800-MHz HTS insert (H800) comprising three nested coils. Each coil is a stack of double-pancake coils wound with 6-mm-wide 75-m-thick REBCO tape. For this H800 generating its self-field of 18.6 T and being exposed to a total field as high as 30.5 T, overbanding each pancake coil is necessary to keep the conductor strain at < 0.6%. Although electromagnetic and mechanical details of the H800 had been considered during its design stage, a parametric study on the overband radial build considering winding tension effect should further confirm the results of our previous analysis. Thus, in this paper, based on Maxwell's equations and the equilibrium equations for mechanical deformation, we examine stress levels that the H800 experiences as H800 undergoes winding-energizing sequences during operation at 1.3 GHz. We also discuss the effects of overband radial build and winding tension on conductor stress in each coil. Finally, based on this analysis, we may further optimize the stainless-steel overbanding and winding tension on each H800 coil.
麻省理工学院弗朗西斯·比特磁体实验室正在建造一台高分辨率的1.3 GHz/54毫米低温超导/高温超导（HTS）核磁共振磁体（1.3 G）。其关键部件之一是一个800 MHz的高温超导插入件（H800），它由三个嵌套线圈组成。每个线圈都是由堆叠的双饼式线圈构成，这些双饼式线圈由宽度为6毫米、厚度为75微米的REBCO带材缠绕而成。对于这个产生18.6 T自场且要承受高达30.5 T总场的H800，对每个饼式线圈进行过带绑扎是必要的，以将导体应变保持在<0.6%。尽管在H800的设计阶段已经考虑了电磁和机械细节，但考虑绕组张力效应的过带径向结构参数研究应进一步证实我们之前分析的结果。因此，在本文中，基于麦克斯韦方程组和机械变形平衡方程，我们研究了H800在1.3 GHz运行期间经历绕组通电序列时所承受的应力水平。我们还讨论了过带径向结构和绕组张力对每个线圈中导体应力的影响。最后，基于此分析，我们可以进一步优化每个H800线圈上的不锈钢过带绑扎和绕组张力。
