High Frequency Gyrotron for DNP/NMR Research.

用于 DNP/NMR 研究的高频回旋管。

• 批准号: 8508938
• 负责人: RICHARD J TEMKIN
• 金额: $ 52.35万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-07 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8508938
• 关键词: 2,4-Dinitrophenol; Amyloid Proteins; Biological; Caliber; Cell Nucleus; Code; Couples; Coupling; Cyclotrons; Detection; Development; Electrons; Engineering; Frequencies; Funding; Goals; Helium; Laboratories; Lead; Magnetism; Mechanics; Membrane Proteins; Methods; Molecular Structure; NMR Spectroscopy; Nitrogen; Noise; Nuclear; Nuclear Magnetic Resonance; Output; Performance; Property; Request for Proposals; Research; Role; Sampling; Series; Signal Transduction; Solid; Solutions; Solvents; Source; Speed; Structure; System; Techniques; Temperature; Testing; Time; Variant; Width; base; biological systems; cold temperature; computer design; design; design and construction; improved; magnetic field; microwave electromagnetic radiation; nitroxyl; novel; operation; programs; public health relevance; research and development; research study; second harmonic; solid state; solid state nuclear magnetic resonance; success; voltage

DESCRIPTION (provided by applicant): The proposed research program is focused on the research and development of a widely tunable, high frequency (527 GHz) gyrotron oscillator for application to dynamic nuclear polarization solid-state nuclear magnetic resonance spectroscopy (DNP/SSNMR). In NMR, signal intensities are intrinsically low due to the small gyromagnetic ratios of the observed nuclei. DNP/NMR experiments can provide signal enhancements of 20 to 400, making DNP/NMR an important technique for elucidating the structure, function, and dynamic properties of biological systems. The full implementation of these techniques at high magnetic fields has been limited by two problems: 1.) the paucity of high power microwave sources that generate microwaves in the region 140 - 600 GHz and 2.) the fact that essentially all NMR magnets operate at fixed field in persistent mode, making it difficult to match the microwave frequency to the correct frequency in the EPR spectrum to optimize DNP. This proposal requests funding to develop a high-stability gyrotron oscillator that provides a solution to these two problems. The 10 to 50 Watt, 527 GHz gyrotron with a tunable bandwidth of 2 GHz will be used in conjunction with an 800 MHz NMR spectrometer, making it the highest magnetic field DNP/NMR spectrometer in the world. This spectrometer should provide dramatic signal enhancement at the very high magnetic fields where contemporary NMR research is currently being performed. The development of the 527 GHz gyrotron presents unique scientific and engineering challenges, including: greatly reduced gyrotron gain when operating at a low voltage and at the second harmonic gyro-frequency; high ohmic loss at high frequency; and the limited bore size of the superconducting magnet. Variation of beam parameters in a conventional gyrotron oscillator with a high Q cavity gives a frequency tuning range of less than 0.1 %, inadequate for this application. We propose to build the 527 GHz gyrotron with a novel tuning approach: namely, by varying the magnetic field and by utilizing a gyrotron cavity that couples a series of high order axial modes. The proposed 527 GHz gyrotron oscillator will benefit greatly from the highly successful results of our research on a tunable 330 GHz gyrotron oscillator. We have recently demonstrated more than 21 Watts of output power from a 330 GHz gyrotron over a tuning range of 1.2 GHz. Tuning was accomplished by varying the magnetic field, the voltage and the cavity temperature. The tuning was thus accomplished without having to provide mechanical tuning of the resonator, assuring more stable, simple, and convenient operating conditions. The proposal presents a complete design of a 527 GHz gyrotron showing that the predicted power level and tuning range are feasible. During year one of the proposed research, we will complete wide-range testing, optimization and commissioning of the tunable 330 GHz gyrotron while designing and ordering long lead time items for the 527 GHz gyrotron. Funding of this continuation proposal is crucial to maintaining progress in this important field of NMR spectroscopy of biomolecules. PUBLIC HEALTH RELEVANCE: The proposed research is directed at building a high frequency microwave source that will greatly enhance the sensitivity of Nuclear Magnetic Resonance (NMR) spectrometers and will therefore dramatically speed up spectral acquisition in NMR experiments on biological solids. The novel gyrotron microwave source will be the highest frequency source in the world for use in enhanced NMR research and, when applied to an 800 MHz NMR spectrometer, should reveal unique molecular structure information. The improved techniques will lead to increased understanding of the structure of amyloid and membrane proteins which are key to understanding their role in biological systems.

描述（由申请人提供）：拟议的研究计划侧重于研究和开发广泛可调的高频（527 GHz）回旋管振荡器，用于动态核极化固态核磁共振波谱（DNP/SSNMR）。在核磁共振中，由于观察到的原子核的旋磁比较小，信号强度本质上较低。 DNP/NMR 实验可以提供 20 至 400 的信号增强，使 DNP/NMR 成为阐明生物系统的结构、功能和动态特性的重要技术。这些技术在高磁场下的全面实施受到两个问题的限制：1.) 缺乏在 140 - 600 GHz 区域产生微波的高功率微波源；2.) 基本上所有 NMR 磁体都在持续模式下的固定场，使得很难将微波频率与 EPR 频谱中的正确频率相匹配以优化 DNP。该提案要求提供资金来开发高稳定性陀螺振荡器，以解决这两个问题。 10至50瓦、527 GHz陀螺仪，可调带宽为2 GHz，将与800 MHz NMR波谱仪配合使用，使其成为世界上磁场最高的DNP/NMR波谱仪。该光谱仪应在当前正在进行当代核磁共振研究的极高磁场下提供显着的信号增强。 527 GHz 陀螺仪的开发提出了独特的科学和工程挑战，包括：在低电压和二次谐波陀螺频率下工作时，陀螺仪增益大大降低；高频时欧姆损耗高；以及超导磁体的有限孔径。具有高 Q 腔的传统回旋管振荡器中光束参数的变化给出了小于 0.1% 的频率调谐范围，这对于该应用来说是不够的。我们建议采用一种新颖的调谐方法构建 527 GHz 陀螺仪：即通过改变磁场并利用耦合一系列高阶轴向模式的陀螺仪腔。所提出的 527 GHz 回旋管振荡器将极大地受益于我们在可调谐 330 GHz 回旋管振荡器方面的研究取得的非常成功的成果。我们最近展示了 330 GHz 陀螺仪在 1.2 GHz 调谐范围内的输出功率超过 21 瓦。通过改变磁场、电压和腔体温度来完成调谐。因此无需对谐振器进行机械调谐即可完成调谐，从而确保了更稳定、简单和方便的操作条件。该提案提出了 527 GHz 陀螺仪的完整设计，表明预测的功率水平和调谐范围是可行的。在拟议研究的第一年，我们将完成可调谐 330 GHz 陀螺仪的大范围测试、优化和调试，同时设计和订购 527 GHz 陀螺仪的长交货期产品。这一延续提案的资助对于维持生物分子核磁共振波谱这个重要领域的进展至关重要。 公共健康相关性：拟议的研究旨在构建一种高频微波源，该源将大大提高核磁共振（NMR）光谱仪的灵敏度，从而显着加快生物固体 NMR 实验中的光谱采集速度。这种新型回旋管微波源将成为世界上用于增强核磁共振研究的最高频率源，当应用于 800 MHz 核磁共振波谱仪时，应能揭示独特的分子结构信息。改进的技术将加深对淀粉样蛋白和膜蛋白结构的了解，这是了解它们在生物系统中的作用的关键。