High Power Millimeter Wave/Terahertz Sources for Magnetic Resonance

用于磁共振的高功率毫米波/太赫兹源

• 批准号: 8058693
• 负责人: RICHARD J TEMKIN
• 金额: $ 52.71万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2013-07-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8058693
• 关键词: 2,4-Dinitrophenol; Amplifiers; Amyloid Proteins; Area; Biological; Cell Nucleus; Coupling; Cyclotrons; Dependence; Development; Electron Nuclear Double Resonance; Electron Spin Resonance Spectroscopy; Electrons; Exhibits; Fourier transform spectroscopy; Frequencies; Funding; Goals; Image; Lead; Liquid substance; Magic; Magnetic Resonance; Malignant Neoplasms; Measurement; Measures; Membrane; Membrane Proteins; Methods; Motivation; Nuclear; Nuclear Magnetic Resonance; Operating System; Output; Pattern; Performance; Physiologic pulse; Powder dose form; Process; Property; Proteins; Radiation; Relative (related person); Relaxation; Request for Proposals; Research; Resolution; Role; Sampling; Scheme; Shapes; Signal Transduction; Solid; Source; Spectrum Analysis; Sterile coverings; Structure; Techniques; Technology; Testing; Time; Tissues; base; biological systems; cancer imaging; cancer therapy; design; design and construction; experience; improved; instrument; instrumentation; interest; magnetic field; meetings; microwave electromagnetic radiation; millimeter; nanosecond; novel; operation; photonics; programs; public health relevance; research study; solid state; success; temperature jump; transmission process

DESCRIPTION (provided by applicant): The proposed research is focused on the development of a 1000 W, 250 GHz gyrotron amplifier for Magnetic Resonance research. Time domain DNP/NMR and EPR experiments have emerged as important techniques for elucidating the structure, function, and dynamic properties of biological systems. The full implementation of these techniques at high frequency has been limited by the lack of microwave power. This proposal requests funding to develop a high power gyrotron amplifier producing nanosecond to microsecond pulses for DNP/NMR and EPR applications at 9T. This renewal proposal builds on the success of our previous research program to design, fabricate and demonstrate a novel 100 W, 140 GHz gyroamplifier for application at 5T. The 140 GHz gyroamplifier has demonstrated a power level of 400 W and bandwidth of 1 GHz in two microsecond pulsed operation at 140 GHz. The amplifier is stable, with no output power detected unless an input drive signal is applied. The amplifier has met all of its major goals and will now be applied to Magnetic Resonance re- search. The proposed 250 GHz gyrotron amplifier research program also benefits from a highly successful program of research at MIT on high frequency gyrotron oscillators for DNP/NMR and EPR applications. The proposed new 250 GHz gyroamplifier will operate at 30 kV, 0.75 A in a magnetic field of 9T with over 60 dB of saturated gain. In order to optimize the performance of the Magnetic Resonance systems operating with high frequency microwaves (THz radiation), we also propose to develop optimized components such as transmission lines, nanosecond switches, and resonators. Progress in THz technology is also valuable for conventional spectroscopy of biological samples, cancer imaging and, possibly, cancer therapy. For NMR, signal intensities are intrinsically low due to the small gyromagnetic ratios of the observed nuclei. It is therefore crucial to develop methods to enhance the sensitivity of NMR experiments. DNP spectroscopy has been developed to routinely record 1D and 2D DNP enhanced magic angle spinning (MAS) spectra of membrane and soluble proteins using biradicals as polarizing agents. The availability of intense microwave pulses will allow the development of new polarization transfer schemes based on coherent processes, such as electron-nuclear Hartmann-Hahn cross polarization schemes, which are more favorable at high magnetic fields. For EPR, the increased excitation bandwidth of the intense microwave pulses of the proposed gyroamplifier will provide us with the possibility to perform high-field Fourier transform spectroscopy and DQ EPR experiments to determine the distance and the orientation between two electron spins in systems of biological interest. Funding of this continuation proposal is crucial to maintaining progress in this important field of spectroscopic research on 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) and Electron Paramagnetic Resonance (EPR) spectrometers and will therefore help to elucidate the properties of biomolecules. 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. High frequency microwaves can also be used in imaging tissue, in detecting cancer and, possibly, in cancer therapy.

描述（由申请人提供）：拟议的研究重点是开发用于磁共振研究的 1000 W、250 GHz 陀螺放大器。时域 DNP/NMR 和 EPR 实验已成为阐明生物系统结构、功能和动态特性的重要技术。由于缺乏微波功率，这些技术在高频下的全面实施受到限制。该提案请求资助开发高功率回旋放大器，为 9T 的 DNP/NMR 和 EPR 应用产生纳秒至微秒脉冲。这项更新提案建立在我们之前的研究计划的成功基础上，该研究计划旨在设计、制造和演示适用于 5T 的新型 100 W、140 GHz 陀螺放大器。 140 GHz 陀螺放大器在 140 GHz 的两微秒脉冲操作中展示了 400 W 的功率水平和 1 GHz 的带宽。放大器是稳定的，除非施加输入驱动信号，否则不会检测到输出功率。该放大器已实现其所有主要目标，现在将应用于磁共振研究。拟议的 250 GHz 回旋管放大器研究计划还受益于麻省理工学院针对 DNP/NMR 和 EPR 应用的高频回旋管振荡器的一项非常成功的研究计划。拟议的新型 250 GHz 陀螺放大器将在 9T 磁场中以 30 kV、0.75 A 的电压运行，饱和增益超过 60 dB。为了优化使用高频微波（太赫兹辐射）运行的磁共振系统的性能，我们还建议开发优化的组件，例如传输线、纳秒开关和谐振器。太赫兹技术的进步对于生物样品的传统光谱学、癌症成像以及可能的癌症治疗也很有价值。对于 NMR，由于观察到的原子核的旋磁比较小，信号强度本质上较低。因此，开发提高核磁共振实验灵敏度的方法至关重要。 DNP 光谱已开发用于使用双自由基作为偏振剂来常规记录膜和可溶性蛋白质的 1D 和 2D DNP 增强魔角旋转 (MAS) 光谱。强微波脉冲的可用性将允许开发基于相干过程的新极化转移方案，例如电子-核哈特曼-哈恩交叉极化方案，该方案在高磁场下更有利。对于 EPR，所提出的陀螺放大器的强微波脉冲的激发带宽的增加将为我们提供执行高场傅里叶变换光谱和 DQ EPR 实验的可能性，以确定生物感兴趣的系统中两个电子自旋之间的距离和方向。这项延续提案的资助对于维持生物分子光谱研究这一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，该高频微波源将大大提高核磁共振（NMR）和电子顺磁共振（EPR）波谱仪的灵敏度，因此有助于阐明生物分子的特性。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。高频微波还可用于组织成像、癌症检测，甚至可能用于癌症治疗。