Harmonic and higher order mode mm-wave klystrons

谐波和高阶模毫米波速调管

• 批准号: ST/K002953/1
• 负责人: Graeme Burt
• 金额: $ 5.58万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FK002953%2F1
• 关键词: Harmonic; higher; order; mode; mm

The Klystron is a well-known, high efficiency amplifier, with a simple structure and scalable dimensions. It is typically designed with cylindrical reentrant cavities in the fundamental mode. However as the frequency of the device increases the size of the structure decreases. At mm-wave frequencies this leads to two problems: 1) Manufacturing the complex small scale structures. 2) The gap voltage decreases as the gap gets shorter leading to less gain.Most mm-wave klystron concepts reported in the literature are simply smaller versions of microwave klystrons. Even if, in principle the dimensions can be scaled according to the frequency increase, the fabrication challenges and the beam characteristic represent a huge obstacle to the realization of a working device when frequency is higher than 50 GHz. This is consequently true for the frequency range around 94 GHz, which is of great interest for communication and radar applications.This proposal is aimed to overcome of the above-mentioned obstacle to the design and realization of a 94 GHz klystron by two innovative design solutions. The first solution is to operate the cavity at a higher order mode, chosen with similar Ez field distribution on the gap cross-section as the fundamental mode. The design will adopt reentrant cavities with square or rectangular shape, to be compatible with a photolithographic fabrication technique. The higher mode operation permits to design the cavities with dimensions larger (at least 4 -5 times) than in case of fundamental mode operation. This eases the technological effort and makes possible a high quality fabrication by mechanical micromachining or by photolithographic processes. Further, the beam tunnel can be larger than in fundamental mode, to support higher beam current. In order to increase the interaction a number of intermediate buncher cavities, spaced all along the drift tube, will be used to increase the beam current modulation.A separate approach uses a lower frequency input cavity to modulate the beam current. As the beam travels down the drift tube beam harmonics start to form hence a higher order mode output cavity at an integer harmonic frequency of the input cavity can be exited hence acting as a high power frequency multiplier. As the input can be a readily available high power microwave source we are able to overcome the low gain of the device.

速调管是一种众所周知的高效率放大器，具有简单的结构和可扩展的尺寸。它通常设计有基模圆柱形凹腔。然而，随着装置的频率增加，结构的尺寸减小。在毫米波频率下，这导致两个问题：1）制造复杂的小规模结构。2)随着差距变短，间隙差距电压减小，导致增益减小。文献中报道的大多数毫米波速调管概念只是微波速调管的较小版本。即使原则上可以根据频率增加来缩放尺寸，但是当频率高于50 GHz时，制造挑战和波束特性代表了实现工作设备的巨大障碍。因此，这是真实的频率范围约94 GHz，这是非常感兴趣的通信和雷达的应用。该建议的目的是克服上述障碍的设计和实现的94 GHz速调管的两个创新的设计解决方案。第一种解决方案是在较高阶模式下操作腔，所述较高阶模式被选择为在差距横截面上具有与基模相似的Ez场分布。该设计将采用方形或矩形形状的凹腔，以与可编程制造技术兼容。较高模式操作允许设计具有比基模操作的情况更大（至少4 - 5倍）的尺寸的腔。这简化了技术工作，并使通过机械微加工或光刻工艺进行高质量制造成为可能。此外，射束隧道可以大于基模中的射束隧道，以支持更高的射束电流。为了增加相互作用，在漂移管上沿着分布若干中间聚束腔，以增加束流调制，另一种方法是使用低频输入腔来调制束流。随着射束向下行进，漂移管射束谐波开始形成，因此可以在输入腔的整数谐波频率处激发高阶模式输出腔，因此充当高功率频率倍增器。由于输入可以是一个现成的高功率微波源，我们能够克服该设备的低增益。

项目成果

2-D particle-in-cell simulations of high efficiency klystrons

高效速调管的二维细胞内粒子模拟

• DOI: 10.1109/ivec.2016.7561813
• 发表时间: 2016
• 作者: Constable D

Ka-band linearizer structure studies for a compact light source

紧凑型光源的 Ka 波段线性化器结构研究

• DOI: 10.1103/physrevaccelbeams.25.112001
• 发表时间: 2022
• 期刊: Physical Review Accelerators and Beams
• 影响因子: 1.7
• 作者: Castilla A