Administrative Supplement to 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) 的行政补充

• 批准号: 10388520
• 负责人: Yukikazu Iwasa
• 金额: $ 19.5万
• 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/10388520
• 关键词: 3-Dimensional; Acute; Administrative Supplement; 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.

在核磁共振最简单的观点中，高场(B0)的优点是提高了灵敏度和分辨率。为 核磁共振波谱、灵敏度和分辨率分别取决于波幅和频率 测量。信号平均实验的单位时间灵敏度和3D实验的分辨率 最理想的改进是ω3，因此也就是B03。因此，提高质子频率，例如，从目前的900兆赫 麻省理工学院-哈佛磁共振中心的最高频率为1.3 GHz，提高了灵敏度和 分辨率提高了3倍。这一更高频率的好处是我们在2000年提出的倡议的基础 通过将低温和高温超导磁体结合起来，向1 GHz核磁共振磁体迈进了一大步， LTS和HTS；2007年，建议的频率提高到1.3 GHz。HTS在频率上是强制性的 因此，在1 GHz以上，我们的1.3 GHz LTS/HTS核磁共振磁体(1.3G)结合了500 MHz LTS核磁共振磁体 (L500)，带有800-MHz高温超导插件(H800)。在这种4K应用中使用HTS导体并不是因为它们的高功率 温度能力，而不是他们实现显著更高的磁场的能力 光是LTS就能联系到。尽管在设计和施工方面付出了最大的努力，但“原封不动”的同质性 核磁共振磁体在现实中将比所要求的规格差两个数量级以上。用于字段 垫片，在这个修订的阶段3BZ的另一个关键活动是现场映射，需要准确的探头定位 沿着优化的路径和精确的测量，从中得出目标场梯度，从而依次 指导设计适当的垫片线圈，在我们的情况下，高温超导和室温(RT)，两者都是 在这个修订后的3BZ阶段设计和建造。因为HTS Insert是臭名昭著的“大量”非 统一的场地，场地垫片我们的1.3G将是具有挑战性的和艰苦的，需要创新的想法。具体的 麻省理工学院于2000年开始的1.3 GHz LTS/HTS核磁共振磁体的最后阶段的目标(SA)是实现两个 核磁共振的关键要求。在头两年，我们将：1)更换2018年3月测试时损坏的H800 使用新的800-MHz高温超导插件(H800N)和2)结合L500和H800N，完成新的非核磁共振30.5- TL500/H800N磁体；在过去的两年里，我们将3)转换非核磁共振30.5-T场，以实现高 分辨率1.3 GHz核磁共振磁铁(1.3克)。为了实现SA3，我们将应用两项创新技术：1)HTS Z1 和Z2垫片线圈，安装在H800N的炮膛内；以及2)电流扫描反转和磁场抖动，以减轻 屏蔽电流场(SCF)是一种不均匀的反磁场，它叠加在主场上，严重地 会降低空间场质量，特别是像我们的H800N这样的高温超导磁体。我们还将部署Ferro- 磁力被动垫片和RT主动垫片，都是我们的设计。我们相信，我们的1.3G将成为 高场核磁共振以及药物发现和开发的重要力量；它将为整个美国核磁共振服务 在未来的几十年里，它将在世界范围内对生物医学科学产生影响。我们还认为， 我们的1.3G将成为高分辨率&gt；1-GHz核磁共振磁体的典范，必须包含HTS插件。