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）：拟议研究的重点是开发用于磁共振研究的1000 W、250 GHz回旋管放大器。时域DNP/NMR和EPR实验已成为阐明生物系统结构、功能和动力学性质的重要技术。这些技术在高频下的全面实施受到微波功率缺乏的限制。该提案要求提供资金，以开发高功率回旋管放大器，产生纳秒至微秒脉冲，用于9 T的DNP/NMR和EPR应用。这一更新建议建立在我们以前的研究计划的成功，设计，制造和演示一种新型的100 W，140 GHz的陀螺放大器在5 T的应用。140 GHz陀螺放大器在140 GHz的两微秒脉冲工作中，功率级为400 W，带宽为1 GHz。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。该放大器已达到其所有主要目标，现在将被应用于磁共振研究。拟议的250 GHz回旋管放大器的研究计划也受益于一个非常成功的研究计划，在麻省理工学院的高频回旋振荡器的DNP/NMR和EPR应用。所设计的250 GHz陀螺放大器工作电压30 kV，电流0.75 A，磁场9 T，饱和增益超过60 dB。为了优化高频微波（THz辐射）磁共振系统的性能，我们还建议开发优化的组件，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常规光谱学、癌症成像以及可能的癌症治疗也是有价值的。对于NMR，由于所观察到的核的小旋磁比，信号强度本质上是低的。因此，开发提高NMR实验灵敏度的方法至关重要。DNP光谱学已经被开发用于常规记录使用双自由基作为极化剂的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的极化转移方案，例如在高磁场下更有利的电子-核Hartmann-Hahn交叉极化方案。对于EPR，所提出的陀螺放大器的强微波脉冲的增加的激发带宽将为我们提供进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的两个电子自旋之间的距离和方向。资助这一延续提案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。 公共卫生关系：拟议的研究旨在建立一种高频微波源，这将大大提高核磁共振（NMR）和电子顺磁共振（EPR）光谱仪的灵敏度，因此将有助于阐明生物分子的特性。改进的技术将导致对淀粉样蛋白和膜蛋白结构的更多理解，这是理解它们在生物系统中作用的关键。高频微波还可以用于成像组织，检测癌症，并可能用于癌症治疗。