行波管中高频特性与非线性理论的研究

【作者】 吕明毅；

【导师】 宫玉彬； 段兆云；

【作者基本信息】 电子科技大学 ， 电子科学与技术， 2007， 硕士

【摘要】 行波管是微波／毫米波电真空器件中最重要的器件之一，它具有高功率、高增益、高效率、宽频带等优点，在通信、雷达、电子对抗等领域中得到了广泛的应用。本论文对螺旋线慢波系统的高频特性等问题进行了深入而细致的理论研究，基于螺旋带模型，定量地分析了由介质夹持杆引入的介质损耗对慢波结构高频特性的影响以及具有衰减器的螺旋线慢波结构的高频特性，同时还基于一维CHRISTINE代码，利用模拟退火算法对螺旋线慢波结构的螺距分布进行了全局优化，从而提高了注—波互作用的电子效率，增大了行波管的输出功率。本论文的主要工作与创新之处：一、基于比螺旋导电面更精确的螺旋带模型，讨论了螺旋线慢波系统中由介质夹持杆引入的介质损耗对慢波系统的高频特性的影响，给出了更精确的色散关系、耦合阻抗和总的衰减常数。二、考虑空间谐波的影响，从理论上分析了具有衰减器的螺旋带慢波系统的高频特性，并进行了相应的数值模拟，定量地给出了衰减器的表面电阻率和工作频率对衰减常数、相位常数和耦合阻抗的影响，并将数值仿真得到的结果与实验数据和由螺旋导电面模型得到的模拟结果进行了比较，同时还提出了一种新的、更精确的衰减器数学建模方式，为利用注—波互作用非线性理论更准确地预测螺旋线行波管的工作性能提供了可能。三、系统地介绍了模拟退火算法的物理背景、概念、原理、应用及其改进，并且基于注—波互作用的新理论——一维的CHRISTINE代码，引入模拟退火算法对螺距跳变螺旋线的螺距分布进行了全局优化，从而达到提高注—波互作用电子效率和输出功率的目的。更多还原

【Abstract】 Traveling Wave Tube (TWT) is one of the most important types ofmicrowave/millimeter wave vacuum tubes. Due to its high power, high gain, highefficiency and broadband, TWT is widely used in telecommunications, radars andelectronic warfare applications. In this dissertation, a theoretical research on the RF(Radio Frequency) characteristics of a helical Slow Wave Structure (SWS) is made.Basing on the tape-helix model, we give quantitative explanations of the effect ofdielectric loss on RF characteristics and an analysis of the attenuator-coated helicalSWS. We also implement and improve the simulated annealing algorithm into 1DCHRISTINE to optimize the electronic efficiency in a helix TWT in which the helixpitch varies.The work and innovations of this dissertation are listed as follows:1. A general theory is developed to account for the effect of the dielectric lossarising from discrete rods on the RF characteristics in an actual helical slow wavestructure (SWS). The effect of the lossy dielectric rods has been studied on severalpropagation parameters, namely, phase propagation constant, interaction impedance andattenuation constant at different operating frequencies.2. An electromagnetic analysis of the RF characteristics of a helix withattenuator-coated dielectric supports is made. Basing on the rigorous tape-helix modeltaking into account the space harmonics, the analysis improves an earlier study on ahelix fitting in a continuous dielectric tube in an overall metal envelope and predicts theattenuation constant, the phase propagation constant, and the interaction impedanceversus the coating surface resistivity at different operating frequencies. The resultsobtained by the present tape-helix model also are validated against typical reportedexperimental results, however, with reference to the special case of no attenuatorcoating. In the meantime, a new attenuation models is set up to input the RFcharacteristics of the helical SWS in the attenuator region into a nonlinear simulation ofa helix TWT to predict the performance of the TWT more accurately.3. Simulated Annealing Algorithm which is a global optimization algorithm for functions of multi continuous variables is introduced. In order to optimize the electronicefficiency of a helix traveling-wave tube in which the helix pitch varies, we implementand improve the simulated annealing algorithm into 1D CHRISTINE, which is aparametric helix TWT code, and optimization results are shown, too.更多还原