A Novel Ultra-Wideband Gyrotron for DNP-NMR Research

描述：我们建议为25 W， 395 GHz的回旋管开发一种可调谐谐振腔/腔，该回旋管具有超过6 GHz（1.5%）的超宽带调谐，整个频段的功率接近恒定。回旋管将用于动态核极化（DNP）增强固态和溶液态核磁共振波谱。利用DNP，核磁共振实验中固有的小信号强度可以提高几个数量级。这一显著提高的总体灵敏度将非常有利于核磁共振光谱的分析应用以及生物大分子的结构测定。目前可用的回旋管，无论是商用的还是在研究实验室中开发的，都有一个< 0.1%的有限调谐范围，在更高的频率下至少有10倍的功率滚降。因此，带有此类回旋管的系统需要带有昂贵扫描线圈的核磁共振磁体，以便使用不同的极化剂进行DNP研究，因为在固定的核磁共振场下，获得最高增强的最佳频率可以跨越远超过1%的带宽。具有超宽带调谐能力的回旋管有几个优点，即，它将(1)消除昂贵的核磁共振扫描线圈和在大范围内扫描磁场相关的风险，(2)使标准频率的回旋管能够升级目前部署的核磁共振磁体（没有扫描线圈和略有不同的场值），而无需重新充电，(3)允许研究新的极化剂。这种新颖的可调谐谐振器/腔将不涉及任何传统的调谐技术，如机械可移动部件或腔变形，这通常限制了回旋管的寿命到几万小时的操作，只允许几百个调谐周期。此外，这种新型腔体不需要在回旋管磁铁中额外的热孔空间，并且与当前的DNP回旋管结构兼容。因此，这个新颖的概念确保了调优带宽可以增加到bbb15倍，而系统成本的增加可以忽略不计。在第一阶段，我们将设计，建造和冷测试新的回旋管腔来证明这一先进的调谐概念。我们还将完成可调谐395 GHz回旋管的设计，该回旋管在600 MHz的DNP调谐带宽上至少具有25 W的功率。第一阶段的冷试验成功验证了创新调谐概念，将使第二阶段的回旋管原型开发成功。作为该项目的最终结果，我们预计Bridge12将提供超宽带可调谐回旋管，其>1.5%调谐以太赫兹频率为中心，与400 MHz （263 GHz）至900 MHz （593 GHz）的NMR光谱仪相对应，用于DNP-NMR光谱。这将大大加快利用核磁共振技术确定与人类疾病研究相关的生物大分子的结构。

DESCRIPTION: We propose to develop a tunable resonator/cavity for a 25 W, 395 GHz gyrotron with an ultra-wideband tuning of more than 6 GHz (1.5%) with near-constant power across the band. The gyrotron will be used for Dynamic Nuclear Polarization (DNP) enhanced solid-state and solution-state NMR spectroscopy. With DNP, the inherently small signal intensities in an NMR experiment can be enhanced by several orders of magnitude. This significantly increased overall sensitivity will be highly beneficial for analytical applications o NMR spectroscopy as well as the structure determination of bio-macromolecules. Currently available gyrotrons, either commercial or under development in research labs, have a limited tuning range of < 0.1% with at least a factor of 10 roll-off in power at the higher frequencies. Hence, systems with such gyrotrons need NMR magnets with expensive sweep coils to allow DNP studies with different polarizing agents because at a fixed NMR field, the optimal frequency for highest enhancement can span well over 1% bandwidth. A gyrotron with an ultra-wide band tuning capability has several advantages, namely, it will (1) eliminate the expensive NMR sweep coil and the risk associated with sweeping the field over wide ranges, (2) enable a standard frequency gyrotron for upgrading currently deployed NMR magnets (without sweep coils and slightly different field values) in the field with a DNP upgrade without the need for recharging them and (3) allow investigation of novel polarizing agents. This novel tunable resonator/cavity will not involve any of the traditional tuning techniques such as mechanically movable parts or cavity deformation which, typically limit the lifetime of the gyrotron to a few tens of thousands o hours of operation and allow only a few hundred tuning cycles. Also, this novel cavity does not require additional warm-bore space in the gyrotron magnet and is compatible with current DNP gyrotron architecture. Hence, this novel concept ensures that the tuning bandwidth can be increased by a factor >15 without a negligible increase in system cost. In Phase I, we will design, build and cold test the novel gyrotron cavity to prove this advanced tuning concept. We will also complete the design of a tunable 395 GHz gyrotron with at least 25 W of power over 6 GHz of tuning bandwidth for DNP at 600 MHz. The successful verification of the innovative tuning concept with the cold test in Phase I will enable the successful development of a prototype gyrotron in Phase II. As an ultimate result of this project, we expect Bridge12 to deliver ultra-broad band tunable gyrotrons with >1.5% tuning centered around terahertz frequencies corresponding to NMR spectrometers in the 400 MHz (263 GHz) to 900 MHz (593 GHz) for DNP-NMR spectroscopy. This will greatly accelerate structure determination of bio- macromolecules of relevance to human disease research by NMR techniques.