【作者】 白春江；

【导师】 李建清；

【作者基本信息】 电子科技大学 ， 物理电子学， 2013， 博士

【摘要】 耦合腔行波管以其输出功率大、增益高、散热效果好等特性，而广泛应用于电子对抗、雷达和通信等领域。依靠传统的经验设计方法很难综合性地进一步提高耦合腔行波管的功率、带宽、增益、效率以及非线性特性等性能，因此，高精度的耦合腔行波管CAD(Computer Aided Design)软件就成为改进设计、提高性能的主要手段。研究耦合腔行波管注波互作用过程是发展CAD软件的基础。因此，深入研究耦合腔行波管注波互作用过程的基础理论，对快速实现耦合腔行波管的结构优化设计，提升管子的输出功率，拓展管子的工作带宽以及改善稳定性等一系列性能都具有重要的意义。本论文的研究工作主要围绕耦合腔行波管注波互作用基础理论和CAD技术实现而展开，主要的工作内容和创新点包括以下几个方面：1.针对耦合腔行波管高频慢波结构的特性，介绍Curnow和MKK两种常用的等效电路模型。这两个电路都能对耦合腔行波管慢波结构进行很好的等效。文中详细推导了这两个等效电路模型的色散公式、总阻抗公式和特性阻抗公式。根据色散公式以及等效电路特点，针对每个等效电路模型，提出两种计算等效结构参量的方法。使用三个不同频段的耦合腔高频结构，从色散和总阻抗方面，对提出的两个电路的两种等效电路参量的计算方法进行了比较。2.数值研究了耦合腔高频慢波结构的色散和阻抗特性。从耦合腔结构冷腔场的解析计算公式出发，结合有限元仿真软件HFSS，研究了耦合腔慢波结构中的场的分布情况，包括轴向场和径向场。研究了耦合腔高频结构中的总阻抗以及总阻抗与耦合阻抗之间的关系。从而为耦合腔行波管注-波互作用过程的模拟提供理论依据。3.分别推导了Curnow和MKK两个等效电路模型的计算矩阵，包括考虑反向波的级联计算矩阵和只考虑前向波的单腔计算矩阵。这些矩阵都可用于互作用过程的模拟计算。与级联计算矩阵相比，单腔计算矩阵中包含的元素少，因此，它的计算速度会更快。在等效电路中用损耗电阻来表示衰减，而耦合腔中的衰减通常都是以dB形式给出的。在级联计算矩阵中，采用牛顿迭代方法，建立了衰减量与等效电路中的损耗电阻的联系，避免了使用复杂的解析公式计算等效损耗电阻的不准确问题。在单腔计算矩阵中，由于只考虑前向波的传播情况，因此，可以通过直接对等效电路模型的端口电压进行衰减以实现对信号进行衰减，从而有效避开了衰减量与等效电路中损耗电阻之间的转换计算问题。4.推导了一维和三维的运动方程、相位方程、场方程和源电流的计算方程。建立了一维和三维的耦合腔行波管注波互作用理论。以美国休斯公司的卫星通信用行波管961HA管子为例，用建立的一维和三维的耦合腔行波管互作用理论进行模拟计算。并将计算结果与实验值进行了比较，模拟结果与实验值基本吻合。由于本理论也可虑考虑反向波情况，因此，本论文所建立的耦合腔注波互作用理论，可以对驱动振荡进行模拟计算。以961HA管子的结构参数为例，对驱动振荡进行了模拟研究。并探讨使用衰减来抑制驱动振荡，以提高耦合腔行波管的最大输出功率。5.结合Curnow等效电路模型，研究了休斯型耦合腔行波管高频结构，提出一种优化这种高频结构的方法，以提高管子的输出功率。并以961HA管子为例，结合编写的一维耦合腔行波管注-波互作用代码对这种优化方法进行验证。结果表明，采用这种优化方法，得到的新结构确实提高了输出功率。通过研究休斯型耦合腔行波管高频结构的结构参量与色散、阻抗以及带宽之间的关系，对这种结构的耦合腔行波管正向设计进行了初步探讨。结合编写的一维耦合腔行波管注-波互作用代码，依据某一Ka波段的耦合腔行波管设计指标，设计出符合互作用指标要求的休斯型耦合腔高频结构。更多还原

【Abstract】 Coupled-cavity traveling-wave tubes (CC-TWTs) are vacuum electronic amplifierswith high gain and high output power. CC-TWTs have been developed for uniquelydemanding applications in communications, radar and electronic counter measures. It isvery difficult to promote performance of CC-TWTs in power, bandwidth, gain,efficiency and nonlinearity comprehensively by traditional design method based onexperience. The technique of modeling and simulation is the key method to improve thecapability of CC-TWTs. The process of beam-wave interaction for CC-TWTs is themost important part of the mechanism and kernel theory for CC-TWTs. And thebeam-wave interaction for CC-TWTs is the foundation of CC-TWTs CAD software.Therefore, it is very helpful for optimizing the structure, improving output power,widening bandwidth and enhancing stability to analyse the beam-wave interactiontheory.In this doctoral dissertation, the work is mainly focused on the study of beam waveinteraction basic theory and the CAD technology of CC-TWTs. And several importantand valuable results are listed as below：1. Two equivalent circuit models are introduced to represent the coupled cavityhigh frequency structure. The two circuits can both give a good representation of thedispersion and total impedance. The formulas about dispersion, total impedance andcharacteristic impedance of the two circuits are also deduced. According to thecharacteristic of the circuits, two approaches to calculate the lumped elements of thecircuits are proposed with the formulas for each circuit. In order to validate theapproaches, the work to compare the approaches with different high frequencystructures which can work in different frequency bands is done. The content ofcomparasion mainly includes the dispersion and total impedance.2. To study the dispersion and total impedance of the coupled cavity highfrequency structure, the simulation software HFSS is used. Combining the analyticalformula of high frequency field and HFSS, the distribution of high frequency field,including axial field and radial field, is discussed in the coupled cavity high frequency structure. The calculation about total impedance and the relationship between theinteraction impedance and total impedance are also discussed. And it is of great use toresearch the beam wave interaction of CC-TWTs.3. Through the equivalent circuits, Curnow and MKK, the matrixes includinglumped elements are construced. The matrixes are divided into two types：single-cavitymatrix and multip-cavity cascaded matrix. The single-cavity matrix is used onlyconsidering the forward wave. While the backward wave is taken into account, themultip-cavity cascaded matrix is used. Comparing with the multip-cavity cascadedmatrix, the single-cavity matrix can calculate faster due to with few matrix elements.Worthing notice, the effect of attenuations is also taken into account in these matrixes.Generaly speaking, in a equivalent circuit, the loss resistance is used to represent theattenuation of the coupled cavity structure. And the unit of loss resistance andattenuation are different. In the multip-cavity cascaded matrix, the Newton-Raphsonmethod is used to obtain the accurate equivalent loss resistance from transform theattenuation. In general, it is difficult and unaccurate to transform the attenuation intoequivalent loss resistance using analytical fornulars. In the single-cavity matrix, thevoltages of the equivalent circuit are attenuated instead of solving the equivalent lossresistance.4. The one-dimensional (1-D) and three-dimensional (3-D) beam wave interactiontheores of CC-TWTs are constructed. And the formulas including phase equation,motion equation, field equation and source current equation are all deduced. TheHughes Aircraft Company’s961HA TWT which is a CC-TWT for intersatellitecommunications is taken as an example to validate the1-D and3-D beam waveinteraction theoties. The simulated results are compared with the experimental results.And the simulated results agree with the experimental results. Since the backward waveis taken into account in the theory, the theory can also be used to predict the driveinduced oscillation (DIO). Also using the parameters of961HA TWT, the DIO issimulated. And it is proved that the approach to controlling DIO and improving themaximum output power by using attenuation is validated.5. The Hughes high frequency structure is analyzed in detail with simplifiedCurnow model and anaystical formulars solving dispersion and total impedance. Amethod which is used to optimize the high frequency structure and improve the output power of CC-TWTs is developed. To validate the method, the961HA TWT is as anexample and the1-D code based on1-D beam wave interaction theory is used. It isproved that the method is useful for improving the output power. Discussing the changeof the dispersion, total impedance and wideband with the dimension of Hughes structure,a preliminary top-down design method which can be used to do fast design forhigh-efficiency coupled-cavity high frequency structure according to the designspecifications of CC-TWTs is developed. And the method is used to design a Ka-bandcoupled-cavity high frequency structure. And the tested results show that thenewly-developed design method works pretty well.更多还原