High Power Microwave Amplifiers to generate smart waveforms for magnetic resonance spectroscopy

高功率微波放大器可为磁共振波谱生成智能波形

• 批准号: 2434709
• 金额: --
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2434709
• 关键词: Power; Microwave; Amplifiers; generate; smart

Fast wave amplifiers offer potential to generate extremely high power microwave pulses. A recent innovation impacting high power microwave amplifiers is the introduction of a weak helical corrugation on the inner wall of nominally cylindrical waveguide. Such a corrugation results in new solutions (eigenmodes) to Maxwell's equations, which may be thought of as a coupling of space harmonics of the modes of an uncorrugated waveguide. Depending on the exact geometry chosen for the corrugation, these new modes can exhibit a nearly constant group velocity in a region where the phase velocity tends to infinity. This arrangement is ideal for tuneable fast wave amplifiers, since the linear dispersion can overlap with the dispersion of a cyclotron mode of an electron beam over a wide frequency range giving wide bandwidth, whilst enhancing efficiency and mitigating against the risk of spurious oscillation. Such amplifiers have demonstrated megawatt capability in the X-band (around 10GHz) with 20% instantaneous bandwidth and efficiency approaching 30%. It is also an ideal wave dispersion for tuneable oscillators where the frequency of the source can be adjusted by changing the magnetic field which supports the electron cyclotron motion of a large orbit beam at the 2nd electron cyclotron harmonic.Here we propose to study tuneable backward wave oscillators and amplifiers in WR-2.2 waveguide band (320GHz to 500GHz) for magnetic resonance spectroscopy applications. We will initially design and construct a tuneable backward wave oscillator in the 360GHz to 395GHz frequency range applying ideas such as the use of a large diametre 5-fold helically corrugated waveguide interaction region. We will also develop new theory and computational models of gyrotron travelling wave amplifiers based on a 5-fold helically corrugated interaction region operating in the 365GHz to 395GHz frequency range.

快波放大器提供了产生极高功率微波脉冲的潜力。最近影响高功率微波放大器的一项创新是在名义上的圆柱形波导的内壁上引入了微弱的螺旋波纹。这种波纹导致了麦克斯韦方程的新解(本征模)，它可以被认为是非波纹波导模式的空间谐波的耦合。根据为波纹选择的确切几何形状，这些新模式可以在相速度趋于无穷大的区域显示出几乎恒定的群速度。这种布置是可调快波放大器的理想选择，因为线性色散可以与电子束回旋模式的色散在较宽的频率范围内重叠，从而提供较宽的带宽，同时提高效率并降低杂散振荡的风险。这类放大器在X波段(约10 GHz)显示出兆瓦能力，瞬时带宽为20%，效率接近30%。对于可调谐振荡器来说，它也是一种理想的波色散，其中源的频率可以通过改变磁场来调节，磁场支持大轨道束在第二电子回旋谐波处的电子回旋运动。在这里，我们建议研究WR-2.2波导带(320 GHz到500 GHz)的可调回波振荡器和放大器，用于磁共振光谱应用。我们将初步设计和构造一个在360 GHz到395 GHz频率范围内可调的反向波振荡器，应用诸如使用大直径5倍螺旋波纹波导相互作用区的想法。我们还将基于365 GHz到395 GHz频率范围内的5重螺旋波纹相互作用区，发展回旋管行波放大器的新理论和计算模型。