220GHz折叠波导慢波结构设计

发布时间：2018-01-16 18:18

本文关键词：220GHz折叠波导慢波结构设计　出处：《北京信息科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：太赫兹,指频率介于0.1THz~10THz之间的电磁波,位于毫米波和红外之间。它具备诸多优点,科学价值重大,应用前景广阔,可用于物体成像、环境监测、医疗诊断,亦可用于卫星通信和军用雷达系统等方面。在太赫兹源研制方面,辐射功率低是限制太赫兹技术发展的主要瓶颈之一,因此需要一种理想的太赫兹辐射源放大器。而行波管是一类应用最广泛的电真空放大器,应用在太赫兹频段,可以实现对太赫兹波的功率放大,用于构建高效率的太赫兹源,对太赫兹技术的发展具有十分重要的意义。慢波结构是行波管的核心部件,折叠波导慢波结构作为一种全金属的结构,散热能力强,带宽大,输入输出耦合结构简单且易于加工,高频损耗小。因此,太赫兹折叠波导行波管吸引了国内外众多研究机构的广泛关注,极具发展潜力。220GHz是太赫兹频段低端的一个大气窗口,有极高应用价值,是各国竞相研究的频段。针对当前小型化、宽频带太赫兹辐射源需求,本文设计了以折叠波导为慢波电路的220GHz行波管,并进行了慢波电路样品加工工艺的初步探索。论文内容如下:(1)对慢波结构的色散特性、耦合阻抗以及损耗特性进行了理论分析,开发了参数获取工具,设计了220GHz折叠波导慢波结构,并在CST微波工作室TM中进行了仿真。冷测特性计算结果表明,该慢波结构在220GHz附近,色散曲线较平缓,耦合阻抗约2?。(2)结合注—波互作用理论,优化设计了互作用电路,在CST粒子工作室TM仿真工具软件中对220GHz折叠波导行波管进行了全管特性仿真,分析了注—波互作用的物理过程,探究了增益与同步电压、互作用电路长度、聚焦磁场、电子发射角度、电子能散度等参数的关系,给出了60周期互作用长度的折叠波导行波管输出信号时域及频域特性,提取了功率水平、增益、带宽等指标。(3)针对220GHz折叠波导慢波结构截面尺寸与标准波导不一致的问题,结合微加工工艺难度和可行性,设计了采用直渐变方式的慢波电路到标准波导过渡段,并在CST微波工作室TM中进行了仿真,驻波比满足整管设计的要求。(4)结合微细加工工艺,对太赫兹折叠波导慢波电路的工艺进行了初步探讨,采用微细电火花技术(WEDM),加工了220GHz折叠波导慢波结构的初步样品,分析了其中存在的问题并提出相应的解决办法,对进一步的工艺优化提出了建议。上述关于220GHz折叠波导慢波结构的理论分析、综合设计、三维注—波互作用模拟仿真、加工工艺的探索等工作,为后续研制220GHz折叠波导行波管打下了基础。
[Abstract]:Terahertz, a electromagnetic wave with a frequency of 0.1 THz-10 THz, is located between millimeter wave and infrared. It has many advantages, great scientific value, wide application prospect and can be used for object imaging. Environmental monitoring, medical diagnosis, satellite communications and military radar systems can also be used. In the development of terahertz sources, low radiation power is one of the main bottlenecks limiting the development of terahertz technology. Therefore, an ideal THz emitter amplifier is needed, and TWT is the most widely used electric vacuum amplifier, which can amplify the THz power. It is very important for the development of terahertz technology to construct high efficiency terahertz source. Slow wave structure is the core component of TWT, and folded waveguide slow wave structure is a kind of all metal structure. Because of its strong heat dissipation, large bandwidth, simple input and output coupling structure, easy processing and low loss at high frequency, THz folded waveguide TWT has attracted wide attention from many research institutions at home and abroad. The high potential .220 GHz is an atmospheric window at the low end of the terahertz band, which has very high application value and is the frequency band studied by many countries. According to the demand of the current miniaturization, broadband terahertz radiation source. In this paper, a 220 GHz TWT with folded waveguide as slow wave circuit is designed, and the processing technology of slow wave circuit sample is studied. The main contents of this paper are as follows: 1) Dispersive characteristics of slow wave structure. The coupling impedance and loss characteristics are analyzed theoretically. A parameter acquisition tool is developed and a 220 GHz folded waveguide slow-wave structure is designed. The simulation results in TM of CST microwave studio show that the slow-wave structure is in the range of 220 GHz, the dispersion curve is smooth and the coupling impedance is about 2? Based on the theory of beam-wave interaction, the interaction circuit is optimized, and the full-tube characteristics of 220GHz folded waveguide TWT are simulated in the TM simulation software of CST particle studio. The physical process of beam-wave interaction is analyzed, and the relationship between gain and synchronous voltage, interaction circuit length, focusing magnetic field, electron emission angle and electron energy divergence is explored. The time-domain and frequency-domain characteristics of the output signal of the folded waveguide TWT with the interaction length of 60 cycles are given. The power level and gain are extracted. Aiming at the problem that the cross section size of slow wave structure of 220 GHz folded waveguide is not consistent with the standard waveguide, it is difficult and feasible to combine the micro-fabrication technology. The transition section from slow wave circuit to standard waveguide is designed and simulated in CST microwave studio TM. The VSWR meets the requirements of the whole tube design. The technology of THz folded waveguide slow-wave circuit is discussed. A preliminary sample of 220GHz folded waveguide slow-wave structure is fabricated by using micro-EDM technique. The existing problems are analyzed and the corresponding solutions are put forward, and suggestions for further technological optimization are put forward. The theoretical analysis and comprehensive design of the 220GHz folded waveguide slow-wave structure are described above. The simulation of 3D beam-wave interaction and the exploration of machining technology have laid the foundation for the further development of 220GHz folded waveguide TWT.
【学位授予单位】：北京信息科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN124

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