带状束新型螺旋线行波管的研究

发布时间：2017-12-28 04:28

本文关键词：带状束新型螺旋线行波管的研究　出处：《电子科技大学》2016年博士论文　论文类型：学位论文

更多相关文章： 螺旋线 带状束 慢波结构 行波管

【摘要】：更高的工作频率和更大的输出功率是行波管发展的两个主要目标。传统的圆螺旋线慢波结构因为具有超宽的工作频带、较高的互作用阻抗以及高增益等优点,在宽带中等功率行波管以及微波功率模块等领域获得广泛应用。然而,当行波管工作频率上升到V波段及以上频段时,慢波结构的尺寸变得非常小,圆螺旋线的三维结构本质使得其精确加工变得困难,同时电子注通道半径也随着工作频率提高被急剧压缩,这些因素极大地限制了圆螺旋线行波管在更高频段场合的应用。为适应行波管高频工作的发展趋势,研究人员提出了矩形螺旋线慢波结构,并基于螺旋导面模型(Sheath Model)对该平面慢波结构的高频特性进行了理论分析,推导得出了基于螺旋导面模型的色散方程,所得结论具有一定的指导意义。然而,基于螺旋导面模型的分析方法忽略了矩形螺旋线周期结构的本质,没有考虑实际螺旋带宽度以及空间谐波对慢波系统高频特性的影响,因而不能反映该结构周期性通带和阻带的特点,在理论处理方法上有所欠缺,同时在色散方程计算的准确性也需要提高。作为一种有着良好应用前景的螺旋类慢波结构,迫切需要更准确的理论来指导矩形螺旋线行波管实际的设计与加工。为此,本论文在前人简化模型的基础上,采用更准确的螺旋导带模型(Tape Model)对矩形螺旋线中电磁波的传播特性进行了深入的研究,在严格电磁理论分析基础上建立了基于周期系统模型的矩形螺旋线色散方程,更准确地掌握了电磁波在矩形螺旋线慢波结构中的传播规律,为矩形螺旋线行波管的设计与加工提供了更可靠的理论指导。另一方面,现有的圆螺旋线行波管普遍采用圆形电子注为能量源,而圆形电子注固有的强空间电荷效应制约了行波管输出功率的进一步提高。为提高现有圆螺旋线行波管的输出功率,需要探索圆螺旋线慢波结构与带状电子注互作用的有效结构及相应的工作机理。为此,本论文分析了圆波导加载内偏心圆螺旋线慢波结构,基于严格的电磁理论分析建立了该偏心慢波系统的特征方程,研究了偏心距离等参数对慢波系统色散和互作用阻抗的影响,为多个圆螺旋线慢波结构与带状电子注的互作用研究奠定了前期理论基础。本论文的主要研究内容分为以下几部分:1.为了更准确地理解矩形螺旋线慢波结构的电磁特性,基于螺旋导带模型,对自由矩形螺旋线慢波结构进行了深入的理论分析。在对矩形螺旋线中面电流展开的基础上,综合应用功率流匹配法和修正的Marcatili法,推导得出了基于周期系统模型的矩形螺旋线色散方程和互作用阻抗解析表达式。与HFSS的仿真结果对比表明基于周期系统理论的矩形螺旋线色散方程具有更高的计算准确性,可以更准确地预测电磁波在矩形螺旋线中的传播规律。上述结果有利于深入了解自由空间矩形螺旋线的高频特性,为其在宽带毫米波行波管的应用奠定了理论基础。2.研究了加载电介质和外接屏蔽腔的矩形螺旋线慢波结构,基于螺旋导带模型,理论推导了介质加载和存在屏蔽腔情形下矩形螺旋线的色散方程和互作用阻抗表达式。数值计算了正常和反常加载情况下矩形螺旋线结构的高频特性,并与HFSS仿真结果以及工作于S波段的矩形螺旋线实验结果进行了对比。结果显示,基于螺旋导带模型的色散方程具有更高的准确性,该色散方程对介质参数和屏蔽腔尺寸对高频特性的影响有着更准确的预测。3.基于注-波互作用线性理论,在螺旋导带模型下,分析得出了矩形螺旋线行波管横向反对称模的热色散方程。数值计算了螺旋线结构参数和电子注参数对行波管增益和工作带宽的影响。结果表明,在相同的电子注参数下,方形螺旋线行波管比等价圆螺旋线(相同的横截面周长和螺距角)行波管具有更高的增益,但工作带宽则小于等价圆螺旋线行波管,而中高宽高比的矩形螺旋线行波管却具有增益和带宽上的综合优势。4.作为多个圆螺旋线慢波结构与带状电子注互作用的基础理论工作,我们分析了圆波导加载内偏心圆螺旋线慢波结构。基于严格的电磁理论分析,利用螺旋线模式的正交性和变态贝塞尔函数的加法定理,推导得出了该偏心慢波系统的特征方程。结果表明,单一的正态螺旋线模式不能同时满足系统的内外边界条件,该偏心慢波结构的场解为多个混合模式的叠加。数值计算表明,偏心距离的出现降低了慢波结构主模在低频段的归一化相速和互作用阻抗,而中高频段的色散与耦合阻抗受偏心位移的影响较小。上述结果有利于深入了解偏心螺旋线慢波结构的高频特性,为多个圆螺旋线慢波结构与带状电子束的互作用研究奠定了前期理论基础。
[Abstract]:Higher working frequency and greater output power are the two main objectives of the development of the TWT. The traditional circular helix slow wave structure is widely applied in broadband, medium power traveling wave tube and microwave power module because of its wide bandwidth, high interaction impedance and high gain. However, when the rise of the TWT frequency to the V band and above the band, the slow wave structure size becomes very small, the three-dimensional structure of the essence of helix makes its precision machining difficult, while the electron beam radius with the working frequency channel is improved sharply compression, these factors greatly limit the application of helix the traveling wave tube in higher frequency applications. In order to adapt to the development trend of high frequency traveling wave tube, the researchers put forward the rectangular helix slow wave structure, and based on the spiral guide surface model (Sheath Model) on the high frequency characteristics of the planar slow wave structure is analyzed and deduced from the dispersion equation of spiral surface based model, the conclusion is the guidance. However, analysis method of spiral surface model based on ignoring the essence of rectangular helical periodic structure, without considering the spiral band width and space harmonic effect on the frequency characteristics of slow wave system, which does not reflect the characteristics of the periodic structure of passband and stopband, lacking in the theory of processing method, the accuracy at the same time in the calculation of the dispersion equation also needs to improve. As a kind of spiral slow wave structure with good application prospects, more accurate theory is urgently needed to guide the actual design and processing of the rectangular helix traveling wave tube. Therefore, in this paper the simplified model, the spiral model is more accurate than the conduction band (Tape Model) on the propagation characteristic of electromagnetic wave in rectangular helix is studied, in the strict electromagnetic theory analysis is established based on dispersion moment spiral cycle system model based on the equation, more accurately grasp the electromagnetic wave in the rectangular helix slow wave propagation structure, rectangular helix TWT design and processing provides a more reliable theoretical guidance. On the other hand, the existing circular helix traveling wave tubes generally use circular electron beam as energy source, while the inherent strong space charge effect of the round electron beam restricts the further improvement of the output power of the TWT. In order to improve the output power of the existing circular helix traveling wave tube, we need to explore the effective structure and the corresponding working mechanism of the interaction between the circular helix slow wave structure and the strip electron beam. Therefore, this paper analyzes the circular waveguide loaded in eccentric helical slow wave structure, the electromagnetic characteristic equation of strict theoretical analysis established the eccentric slow wave system based on the study of the influence of parameters of eccentric distance on the slow wave dispersion and interaction impedance, multiple circular helix slow laid early the theoretical basis of the interaction of wave structure and sheet electron beam. The main research contents of this paper are divided into the following parts: 1.. In order to understand the electromagnetic characteristics of the rectangular helical slow wave structure more accurately, based on the spiral conduction band model, the theoretical analysis of the free rectangular helix slow wave structure is carried out. Based on the expansion of the middle surface of the rectangle spiral line, the power flow matching method and the modified Marcatili method are applied synthetically, and the dispersion equation and the interaction impedance expression of the rectangular helix are derived based on the periodic system model. Compared with the simulation results of HFSS, it is shown that the dispersion equation based on the theory of periodic system has higher accuracy and can predict the propagation of electromagnetic waves in a rectangular spiral. The above results are helpful to understand the high frequency characteristics of the rectangular spiral line in free space, and lay a theoretical foundation for its application in the broadband millimeter wave traveling wave tube. 2., the rectangular helix slow wave structure loaded with dielectric and external shielding cavity is studied. Based on the spiral conduction band model, the dispersion equation and interaction impedance expression of the rectangular helix under the condition of dielectric loading and shielding cavity are derived theoretically. The high frequency characteristics of the rectangular helical structure under normal and abnormal loading are numerically calculated, and compared with the HFSS simulation results and the experimental results of the rectangular helix in S band. The results show that the dispersion equation based on the spiral conduction band model has higher accuracy. The dispersion equation has a more accurate prediction of the influence of the medium parameters and the size of the shielding chamber on the high-frequency characteristics. 3. based on the linear theory of injection wave interaction, the thermal dispersion equation of the transverse anti symmetric mode of a rectangular spiral traveling wave tube is obtained under the model of the spiral guide band. The effects of the structural parameters and the electron beam parameters on the gain and bandwidth of the TWT are numerically calculated. The results show that the parameters of the beam under the same square helix traveling wave tube than equivalent helix (cross section perimeter and the same pitch angle) traveling wave tube has higher gain, but the bandwidth is less than the equivalent helix traveling wave tube, and the rectangular helix in high aspect ratio of the traveling wave tube has the comprehensive advantages of the gain and bandwidth. 4., as the basic theoretical work of interaction between multiple circular helix slow wave structures and strip electron beam, we analyzed the eccentric circular helix slow wave structure loaded by circular waveguide. Based on strict electromagnetic theory analysis, the characteristic equation of the eccentric slow wave system is derived by using the orthogonality of the spiral mode and the addition theorem of the distorted Bessel function. The results show that the single normal helix mode cannot satisfy both the internal and external boundary conditions of the system, and the field solution of the eccentrically slow wave structure is a superposition of multiple mixed modes. The numerical calculation shows that the eccentric distance reduced slow wave structure in the main mode frequency normalized phase velocity and the interaction impedance, the influence of the dispersion and coupling impedance in high frequency by eccentric displacement
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN124

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