A high-resolution 1.3-GHz LTS/HTS NMR magnet (1.3G)

高分辨率 1.3 GHz LTS/HTS NMR 磁体 (1.3G)

• 批准号: 10224650
• 负责人: Yukikazu Iwasa
• 金额: $ 55.91万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10224650
• 关键词: 3-Dimensional; Acute; Award; Charge; Communities; Event; Frequencies; Funding; Future; Goals; Helium; High temperature of physical object; Lead; Liquid substance; Magnetic Resonance; Measurement; Medical; Modeling; NMR Spectroscopy; National Center for Research Resources; Phase; Positioning Attribute; Protons; Research; Resolution; Science; Signal Transduction; Site; Source; Techniques; Technology; Temperature; Testing; Theft; Time; United States National Institutes of Health; cold temperature; cost; design; design and construction; drug development; drug discovery; experimental study; ferrite; improved; innovation; magnetic field; programs; screening; wound

In the simplest view of NMR, the advantages of higher field (B0) are improved sensitivity and resolution. For NMR spectroscopy, sensitivity and resolution depend, respectively, on amplitude and frequency of measurement. Sensitivity per unit time in signal averaging experiments and resolution for 3D experiments both ideally improve as ω3 and, hence, B03. Thus, increased proton frequency, for example, from 900 MHz, currently the highest frequency at the MIT-Harvard Magnetic Resonance Center, to 1.3 GHz, increases sensitivity and resolution by a factor of 3. This benefit of higher frequency was the basis of our initiative in 2000 to propose a long march towards a 1-GHz NMR magnet by combining low- and high-temperature superconducting magnets, LTS and HTS; in 2007 the proposed frequency was increased to 1.3 GHz. HTS is mandatory at frequencies above 1-GHz, thus, our 1.3-GHz LTS/HTS NMR magnet (1.3G) combines a 500-MHz LTS NMR magnet (L500) with an 800-MHz HTS insert (H800). HTS conductors are used in this 4K application not for their high- temperature capabilities, but rather for their ability to achieve significantly higher magnetic field than can be reached by LTS alone. Despite the best efforts in design and construction, the homogeneity of an “as-wound” NMR magnet in reality will be more than two orders of magnitude away from required specifications. For field shimming, another critical activity in this Revised Phase 3BZ is field mapping, requiring exact probe positioning along optimized path and accurate measurement, from which to derive the target field gradients that in turn guide the design of appropriate shim coils, in our case, of HTS and room-temperature (RT), both to be designed and built in this Revised Phase 3BZ. Because HTS insert is notorious as a source of “large” non- uniform field, field shimming our 1.3G will be challenging and laborious, requiring innovative ideas. The specific aims (SA) of the last phase of this MIT 1.3-GHz LTS/HTS NMR magnet that began in 2000 are to achieve two vital requirements for NMR. In the first two years, we will: 1) replace the H800 damaged in March 2018 test with a new 800-MHz HTS insert (H800N) and 2) combine L500 and H800N to complete a new non-NMR 30.5- T L500/H800N magnet; and in the last two years we will 3) convert the non-NMR 30.5-T field to realize a high- resolution 1.3 GHz NMR magnet (1.3G). To achieve SA3, we will apply two innovative techniques: 1) HTS Z1 and Z2 shim coils, installed in the bore of H800N; and 2) current-sweep-reversal and field-shaking to mitigate the screening-current field (SCF), a non-uniform diamagnetic field, superposed on the main field that severely degrades the spatial field quality particularly for HTS magnets like our H800N. We will also deploy ferro- magnetic passive shimming and RT active shimming, both of our design. We believe that our 1.3G will become a vital force in high-field NMR as well as for drug discovery and development; it will serve the entire U.S. NMR community for decades to come and have a worldwide impact on biomedical sciences. We also believe that our 1.3G will become a model for high-resolution >1-GHz NMR magnets that must incorporate HTS inserts.

从NMR的最简单角度来看，较高场（B0）的优势是提高灵敏度和分辨率。为了 NMR光谱，灵敏度和分辨率分别取决于放大器和频率 测量。在信号平均实验和分辨率的3D实验中，每单位时间敏感性 理想地改善为ω3，因此，B03。这是从900 MHz提高的质子频率，目前 MIT - Harvard磁共振中心的最高频率达到1.3 GHz，提高了灵敏度，并且 分辨率为3。较高频率的好处是我们在2000年提出的计划的基础 通过将低温和高温超导磁体结合起来，长期前进到1-GHz NMR磁铁 LTS和HTS；在2007年，提出的频率增加到1.3 GHz。 HTS是强制性的 因此，我们的1.3-GHz LTS/HTS NMR磁铁（1.3G）在1-GHz以上结合了500-MHz LTS NMR磁铁 （L500）带有800 MHz HTS插入物（H800）。 HTS导体用于此4K应用中，而不是其高 温度能力，而是因为它们获得明显更高磁场的能力，而不是 仅由LTS到达。尽管在设计和构建方面尽了最大的努力，但“陷阱”的同质性 实际上，NMR磁铁将与所需规范相距两个以上的数量级。对于字段 颤抖的，在此修订后的3Bz阶段的另一个关键活动是现场映射，需要精确的探针定位 沿优化的路径和准确的测量，从中得出目标场梯度 在我们的情况下，指导合适的垫片线圈的HTS和室温（RT）的设计都是 在此修订后的3BZ中设计和建造。因为HTS插入物是臭名昭著的，是“大”非 - 统一的田地，使我们的1.3克造成的领域将受到挑战和费力，需要创新的思想。具体 该MIT 1.3-GHz LTS/HTS NMR磁铁的目标（SA）是2000年开始的 NMR的重要要求。在最初的两年中，我们将：1）更换2018年3月损坏的H800测试 使用新的800-MHz HTS插入物（H800N）和2）组合L500和H800N，以完成新的非NMR 30.5-- T L500/H800N磁铁;在过去的两年中，我们将3）转换非NMR 30.5-T场，以实现高 分辨率1.3 GHz NMR磁铁（1.3G）。要实现SA3，我们将采用两种创新技术：1）HTS Z1 和Z2垫片线圈，安装在H800N的孔中； 2）电流扫荡和磁场震动以减轻 筛选电场（SCF），一种不均匀的磁磁场，在主场上超级置换 降低了空间场质量，尤其是针对HTS磁铁等H800N。我们还将部署 磁性被动式光滑和RT主动弹跳，这两种设计。我们相信我们的1.3克将成为 高场NMR以及药物发现和发育的重要力量；它将为整个美国NMR服务 几十年来，社区将对生物医学科学产生影响。我们也相信 我们的1.3G将成为必须结合HTS插入物的高分辨率> 1-GHz NMR磁铁的模型。