S波段等离子体耦合腔行波管耦合结构的理论设计与测试

【作者】 李貌；

【导师】 谢文楷；

【作者基本信息】 电子科技大学 ， 等离子体物理， 2008， 硕士

【摘要】 耦合结构的设计和调整是研制耦合腔行波管的重要一环。虽然高频系统的特性是决定管子工作带宽的根本,但是耦合结构的频率响应也会影响器件的整体工作频带。耦合结构作为行波管中一个关键部件,它使高频功率能无损耗的或以尽可能小的损耗(包括反射损耗和电阻性损耗)从外传输线传送到管内慢波结构上,或从管内慢波结构传输到外传输线。在这两种性能不同的传输线之间存在着电磁场转换、阻抗匹配的问题。本文以长线等效线路理论为基础,把休斯结构行波管的耦合腔转化为对应的四端口等效网络,并应用等效电路中的电压、电流波来代替慢波系统的传播特性。用等效线路的方法来分析耦合腔体固有谐振频率和耦合缝隙的谐振频率,缝隙的等效传输线阻抗。等效线路法作为一种近似分析法,可以避免计算复杂边界条件下场的问题。本文利用高频三维电磁场仿真软件CST微波工作室,设计了S波段耦合腔行波管的耦合结构,并分析计算了常用的几种耦合结构:直线渐变结构、曲线渐变结构和阶梯耦合结构的宽带匹配性能,并分别计算出了这三种结构的具体尺寸和电压驻波比。通过比较这三种结构各自的性能特点,重点对阶梯耦合结构进行优化设计,使之在满足电压驻波比的要求下,整个耦合结构的长度最短。通过对三阶耦合结构的仿真尺寸进行调整,使其既能满足耦合结构的性能要求,又能满足机械加工的精度要求。按调整后的数据加工两件三阶耦合段耦合结构,并设计了测试平台和测试方法,实测了三阶耦合结构的电压驻波比。测试结果验证了该组数据可以直接用于真空或填充等离子体的S波段耦合腔行波管的整管设计中。更多还原

【Abstract】 Design and adjustment for coupled structure is an important step to develop the coupled-cavity traveling-wave tube. Although the high-frequency system determines the characteristics of the fundamental bandwidth of tube, but the frequency response of coupled structure also affects the overall bandwidth.Coupled structure as a key component in coupled-cavity traveling-wave tube, which makes high-frequency power can be no loss or the loss as small as possible (including resistive loss and reflection loss) from the outside transmission lines to the slow-wave structure or from the slow-wave structure to the outside transmission lines. There are some appearances such as electromagnetic conversion, impedance matching between the two different performances transmission lines.This paper is based on the theory of long-line equivalent circuits. It changes the Hughes coupled-cavity traveling-wave tube into the four-port equivalent networks correspondingly. It uses the voltage and current of equivalent circuits to replace the propagation characteristics of slow-wave system. It uses the models of equivalent circuit to analyze the inherent resonant frequency of coupled-cavity and the resonant frequency of slot. The equivalent line method is a similar analysis, it can be avoided the calculation of complex boundary conditions.This paper uses three-dimensional high-frequency electromagnetic simulation software CST Microwave studio to analyze and calculate the broadband match performance of three transition structures which used in S-band coupled-cavity traveling-wave tubes. The transition structures include linear structure, surface structure and the step structure. At last, it calculates the VSWR of respective structures. Comparison of the three respective characteristics and focusing on the third-order structure, this paper optimize the design to meet the VSWR requirements. However, the length of third-order structure is the shortest among the three structures.Adjusting of the simulation size of the third-order structure, it can meet the requirements both in the performance and the precision of manufacture. Two transitions were produced, and the measurable moth was designed on the test platform. The test results can be directly used in the design of tube.更多还原