Persistent-mode, Liquid-helium-free, Robust Bi2212 Magnets for MRI and >1GHz NMR

用于 MRI 和 >1GHz NMR 的持久模式、无液氦、坚固的 Bi2212 磁铁

• 批准号: 9409328
• 负责人: Alexander Otto
• 金额: $ 22.5万
• 依托单位: SOLID MATERIAL SOLUTIONS, LLC
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9409328
• 关键词: Alloys; American; Area; Caliber; Charge; Data; Development; Environmental Wind; Evaluation; Foundations; Goals; Helium; High temperature of physical object; Industry; Joints; Laboratories; Length; Liquid substance; Magic; Magnetic Resonance Imaging; Measures; Mechanics; Methods; Modulus; Performance; Phase; Price; Process; Production; Program Development; Property; Proteins; Psychological reinforcement; Reaction; Refrigeration; Resolution; Sales; Sampling; Small Business Technology Transfer Research; Solid; Stress; System; Techniques; Technology; Temperature; Testing; Texture; Thinness; United States National Institutes of Health; Work; base; cold temperature; cost; density; design; experience; improved; instrument; magnetic field; melting; operation; prevent; programs; prototype; solid state; solid state nuclear magnetic resonance; stress tolerance; wound

Superconducting magnets are required for MRI systems that can operate at elevated temperatures and with higher magnetic field without the expensive and in many places, unavailable liquid helium that is required with Low Temperature Superconductors (LTS), and for enabling NMR instruments to operate above the 23 T LTS field limit. High Temperature Superconductors (HTS) provide the best options for advancing the performance of these instruments at the lower-cost elevated temperatures of mechanical refrigeration provided they can be made with the required form, strength, uniformity and current density into persistent current coils. The Magnet Technology Division (MTD) of the MIT Francis Bitter Magnet Laboratory (FBML), our partner in this Phase I STTR Program, was first to recognize and propose to the NIH in 1999, that HTS-based conductors must be incorporated into MRI and NMR magnets in order to surpass these limits. Among HTS conductors, only 2212 wire can provide superior Je in much higher operating temperatures and magnetic fields while in principle enabling wire forms, for example, round and rectangular, that are proven to work with LTS. However, in order to meet this demand, 2212 coils must be developed with: 1) improved wire stress and bend tolerance in long lengths to allow for simpler coil fabrication and operation with large Lorentz forces, 2) capability for superconducting joints to allow much lower costs and more uniform fields via persistent current operation modes, and 3) high, uniform current densities in layer-wound configurations. Solid Material Solutions (SMS) is now developing coiled forms of strong, rectangular 2212 wire with focus in this program on a first-of-its-kind, persistent mode HTS coil that is made with strong 2212 wire and superconducting joints. Firstly, SMS, with its partner, the MTD at MIT-FBML, will develop a superconducting joint technique for its strong, rectangular, high current density 2212 wire. Joint configuration, melt texture parameters and wire / joint Ic’s will be investigated based on the results of a preliminary study that has already demonstrated that a superconducting joint can be produced between 2212 wire ends. Secondly, the technique will be applied to develop superconducting joints and a prototype persistent current switch. Joints will be prepared between reinforced wire ends and heat treatments completed, followed by Ic tests of joints as well as coiled wire sections. Using the best samples, a method for switching to persistent mode will be established with heaters, and with field-decay rates characterized to demonstrate that persistent current carrying joints can be achieved with coiled strong 2212 wire. Thirdly, a first persistent mode demonstration HTS coil will be designed, produced and tested, based on our strong 2212 wire and coil making know-how. This coil will be designed and built so that it can generate a central field of up to about 5 T at or below Ic, with loop-closing superconducting joints, and heater to allow switching to persistent mode. It will be tested at 4.2 K in driven current mode up to Ic and then with a background field for a total field of > 8 T. It will then be charged to different current levels, followed by switching to persistent mode. Tests will be completed to measure its field decay rates in background fields up to about 4 T, in order to characterize persistent mode properties and demonstrate our capability to produce and operate strong-wire based 2212 coils in persistent mode. When fully developed, this advance will enable the practical production of persistent mode HTS magnets based on our 2212 superconductor, for use in liquid He-free, and higher field MRI as well as >1GHz NMR systems.

MRI 系统需要超导磁体，能够在高温下运行 更高的磁场，而无需使用低所需的昂贵且在许多地方无法获得的液氦 温度超导体 (LTS)，使 NMR 仪器能够在 23 T LTS 场限制之上运行。 高温超导体 (HTS) 为提高这些材料的性能提供了最佳选择 仪器可以在机械制冷的较低成本高温下制造，前提是它们可以用 磁铁技术部将所需的形状、强度、均匀性和电流密度制成持续电流线圈。 我们在第一阶段 STTR 计划中的合作伙伴，麻省理工学院弗朗西斯苦磁实验室 (FBML) 的 (MTD) 是第一个 1999 年认识到并向 NIH 提出建议，基于 HTS 的导体必须纳入 MRI 和 NMR 为了超越这些限制，在 HTS 导体中，只有 2212 线可以在很多方面提供优异的 Je。 更高的工作温度和磁场，同时原则上可实现线材形状，例如圆形和 矩形线圈，已被证明可与 LTS 配合使用。但是，为了满足这一需求，必须开发 2212 线圈。 具有：1) 改进了长长度的导线应力和弯曲容差，以简化线圈制造和操作 具有较大的洛伦兹力，2) 超导接头的能力可实现更低的成本和更均匀的场 通过持续电流工作模式，以及 3) 层绕固体配置中的高、均匀电流密度。 Material Solutions (SMS) 目前正在开发高强度矩形 2212 线材的卷绕形式，重点关注此项目 首创的持久模式 HTS 线圈由坚固的 2212 导线和超导接头制成。 首先，SMS 与其合作伙伴 MIT-FBML 的 MTD 将为其开发超导联合技术。 坚固、矩形、高电流密度 2212 焊丝 接头配置、熔体织构参数和焊丝/接头 Ic。 将根据初步研究的结果进行调查，该研究已经证明超导 2212线端之间可产生接头。 其次，该技术将应用于开发超导接头和原型持续电流 将在增强线端之间准备接头并完成热处理，然后进行 Ic 测试。 使用最好的样本，切换到持久模式的方法将是。 建立了加热器，并具有场衰减率，以证明持续载流接头 可以使用坚固的 2212 线圈线圈来实现。 第三，第一个持久模式演示高温超导线圈将根据我们的技术进行设计、生产和测试。 强大的 2212 电线和线圈制造技术将设计和制造该线圈，使其能够产生中心磁场。 在 Ic 或以下时高达约 5 T，具有闭环超导接头和加热器以允许切换到持久 它将在高达 Ic 的驱动电流模式下在 4.2 K 下进行测试，然后使用总场 > 8 的背景场进行测试。 T. 然后将充电到不同的电流水平，然后切换到持续模式，测试将完成。 测量高达约 4 T 的背景场中的场衰减率，以表征持续模式 特性并展示我们在持久模式下生产和操作基于强线的 2212 线圈的能力。 当完全开发出来时，这一进步将使得基于我们的技术的持久模式高温超导磁体的实际生产成为可能。 2212 超导体，用于无液氦、高场 MRI 以及 >1GHz NMR 系统。