A Benchtop Cryogen-Free 23.5-T/25-mm-RT-Bore Magnet for 1-GHz microcoil NMR Spectroscopy

用于 1 GHz 微线圈 NMR 光谱的台式无冷冻剂 23.5-T/25-mm-RT 孔径磁铁

基本信息

批准号：
10708850
负责人：
Dongkeun Park
金额：
$ 39.24万
依托单位：
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-23 至 2026-08-31
项目状态：
未结题

项目摘要

Project Summary In this project we propose to develop a benchtop cryogen-free 23.5-T high-temperature superconducting (HTS) magnet for 1-GHz microcoil nuclear magnetic resonance (NMR) spectroscopy. Higher-field magnet offers better resolution and sensitivity, enabling analysis of larger molecules like complex proteins, however currently available ≥1-GHz NMR magnets are very expensive and require a vast installation site, limiting ≥1-GHz NMR spectroscopy to a few labs in the world. A benchtop microcoil NMR magnet by definition 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 workbench. Also, LHe-free operation enables the user to be independent from a cooling source in short supply. As a preliminary work (R21GM129688), we have completed a 12.5-mm-cold-bore HTS REBCO magnet prototype and successfully operated it up to 25 T at 10 K cooled by a cryocooler only, without liquid helium, verifying our high-field REBCO magnet design with the proposed screening-current reduction method. Based on these preliminary results and pioneering design concept, we will first design and build a cryogen-free, shielded all-REBCO 23.5-T/25-mm-RT-bore magnet having a 5-gauss fringe field radius of 1.5 m, and then convert this non-NMR-field 23.5-T magnet to a benchtop 1-GHz microcoil NMR magnet having a high homogeneity of <0.1 ppm over a 5-mm-diameter, 10-mm-length cylindrical volume. We also intend to use an in-house built NMR probe to demonstrate the proposed magnet. This benchtop magnet will incorporate all the innovative design and operation concepts validated by the prototype magnet in our preliminary R21 program: 1) all-HTS composition and operation at above 4.2 K cooled only by a cryocooler, the first ever >4.2-K operation among all ultra-high- field superconducting magnets; 2) extremely-thin-copper-layered no-Insulation winding technique that makes a REBCO magnet very compact, mechanically robust, and self-protecting; 3) a single coil formation that leads, compared with the traditional multi-nested high-field NMR magnet, to simpler and more affordable manufacturing processes; 4) operational temperature-controlled screening-current reduction method which reduces peak stresses within the REBCO coil and field errors; and 5) cryogenic design for conduction-cooling operation. We intend to adopt a passive shielding by using iron to reduce the 5-gauss radius within 1.5 m. To achieve a target field homogeneity, we will adopt three—superconducting, ferromagnetic, and room-temperature—shimming technique which will be complemented by our 1.3-GHz/54-mm high-resolution NMR magnet, currently under development at the FBML, for which we are developing innovative field-shimming techniques. We envision this benchtop cryogen-free 1-GHz microcoil NMR magnet will become a very powerful and affordable research tool for the NMR based structural biology community who eagerly anticipates higher operating frequencies. We believe that the enabling technologies of our proposed benchtop magnet is poised to lead HTS magnet technology to liquid-helium-free >1-GHz NMR magnets.

项目概要在这个项目中，我们建议开发一种台式无制冷剂 23.5-T 高温超导 (HTS) 用于 1-GHz 微线圈核磁共振 (NMR) 光谱的磁铁更高磁场的磁铁提供更好的性能。分辨率和灵敏度，可以分析复杂蛋白质等较大分子，但目前可用的 ≥1-GHz NMR 磁体非常昂贵，并且需要广阔的安装场地，限制了 ≥1-GHz NMR 台式微线圈 NMR 磁体顾名思义是紧凑的，因此它的结构紧凑。成本将比标准 NMR 磁体低近一个数量级，并且可放置在此外，无 LHe 操作使用户能够独立于供应短缺的冷却源。作为前期工作 (R21GM129688)，我们完成了 12.5 毫米冷孔 HTS REBCO 磁体原型并成功地将其在 10 K 下运行至 25 T，仅通过低温冷却器冷却，无需液氦，使用所提出的屏蔽电流降低方法验证我们的高场 REBCO 磁体设计。这些初步成果和开创性的设计理念，我们将首先设计和建造一个无制冷剂、屏蔽式 all-REBCO 23.5-T/25-mm-RT-bore 磁铁，具有 5 高斯边缘场半径 1.5 m，然后将其转换非 NMR 场 23.5-T 磁体到具有 <0.1 高均匀性的台式 1-GHz 微线圈 NMR 磁体 ppm 在直径 5 毫米、长度 10 毫米的圆柱形体积上我们还打算使用内部构建的 NMR。探针来演示所提议的磁铁，该台式磁铁将全部采用创新设计和我们初步 R21 计划中的原型磁体验证了操作概念：1) 全高温超导成分并在 4.2 K 以上运行，仅由制冷机冷却，这是所有超高运行中首次 >4.2-K 运行场超导磁体；2）极薄铜层无绝缘绕组技术，使 REBCO 磁铁非常紧凑、机械坚固且具有自我保护功能 3) 单线圈结构，与传统的多层嵌套高场核磁共振磁体相比，制造更简单、更经济 4) 可操作的温度控制屏蔽电流降低方法，可降低峰值 REBCO 线圈内的应力和场误差；5) 传导冷却操作的低温设计。拟采用铁被动屏蔽的方式，将1.5m内的半径降低到5高斯，以达到目标。为了场均匀性，我们将采用三种——超导、铁磁和室温匀场该技术将得到我们的 1.3 GHz/54 mm 高分辨率 NMR 磁体的补充，目前正在我们正在 FBML 开发创新的场匀场技术。台式无冷冻剂 1 GHz 微线圈 NMR 磁体将成为功能强大且价格实惠的研究工具适合基于 NMR 的结构生物学界，他们热切期待更高的工作频率。相信我们提出的台式磁体的支持技术将引领高温超导磁体技术应用于无液氦 >1-GHz NMR 磁体。