W波段高阶模回旋行波管高频系统研究

发布时间：2018-06-17 15:06

本文选题：TE_(12)高阶模回旋行波管 + TE_(12)输入耦合器　；参考：《电子科技大学》2017年硕士论文

【摘要】：回旋行波管作为电真空器件家族中重要一员,具有高功率宽频带的特点,在毫米波雷达、毫米波通讯、电子战等方面具有广泛的应用前景。然而回旋行波管工作在W或更高频段时,若工作模式仍然采用TE11或TE01等低阶模式,高频尺寸会变小。这样带来的问题是管子功率容量受限,易发生电子截获,加工困难等。采用高阶模式作为回旋行波管的工作模式可以有效的解决这一问题。因而研究高阶模回旋行波管具有重要的意义。围绕高阶模回旋行波管的研究,本论文主要做了以下两个方面的研究工作:一是对以TE12模式作为工作模式的回旋行波管的高频互作用结构以及输入输出系统进行了研究;二是围绕回旋行波管中常用到的低/高阶模式激励器进行了研究。主要研究内容及结果如下:第二章对以TE12模式作为工作模式的回旋行波管的高频结构进行了设计研究。首先基于小信号理论计算了工作模式TE12以及与TE12模式色散曲线几乎重合的TE41模式的起振电流。研究计算表明当磁场取为切点磁场的0.988倍时,TE12、TE41模式的起振电流达到10A以上,因而工作电流为10A时,可以保证这两个模式不发生绝对不稳定性。基于小信号理论同时也计算了与电子回旋模色散曲线交于kz负半轴的可能发生返波振荡的模式的无损起振长度,以及各模式起振长度达到20cm时相应所需要的损耗值。然后基于小信号理论计算的结果仿真分析了材料对各模式的损耗情况,并确定了一个可以稳定工作的介质分布加载高频结构。最后分析了光滑段长度、电压、磁场等的改变对高频输出的影响。第三章对TE12模式回旋行波管的输入输出系统进行了研究。设计了单Y分支Bragg反射器式输入耦合器,针对同一单Y分支结构设计了两种Bragg反射器,解决了传统截止波导在高频段尺寸过小的问题,加工测试了一个带矩形波纹波导Bragg反射器的输入耦合器。为了进一步提高输入耦合器的转换效率,提出了一种双扭Y分支输入耦合器结构,仿真结果显示相较于单Y分支结构TE12模式的转化从-1dB左右提高到了-0.5dB左右。输出窗的设计中间层为蓝宝石,厚度1mm,匹配石英的厚度为0.42mm,仿真及理论计算显示带宽满足设计要求,热分析结果显示窗片可以有效工作,最后加工测试了单层蓝宝石窗片。第四章对回旋行波管中常用到的模式激励器进行了研究。首先提出了一种新型的可以激励TE0n/TE2n/TE1n'模式的激励器,设计思路为矩形TE10→矩形TEn'0→圆波导TE0n/TE2n/TE1n'。该模式激励器可以激励起低阶/高阶模式,结构紧凑,加工简便,模式纯度高,工作带宽较宽。在我们提出的结构基础上设计加工测试了一个低阶的TE01模式激励器、TE01/TE21模式激励器(同一种拓扑结构)、以及一个高阶的TE13模式激励器,并设计了一个高阶的TE12模式激励器以用于TE12模式高阶模回旋行波管中。最后还设计测试了一个高阶模TE13模式输入耦合器,相较于TE12模式输入耦合器TE13模式输入耦合器的竞争模式更加难以抑制。针对这个难点提出了波导壁侧壁开槽的思想,破坏竞争模式的电场结构,抑制竞争模式的形成,并提高设计模式的转化效率。研究采用高阶模的回旋行波管可以避免采用低阶模时在W频段或更高频段因尺寸过小带来的功率容量受限、加工困难等问题。低阶/高阶模式激励器的研究对于回旋行波管的冷测和热测实验具有重要意义。
[Abstract]:Cyclotron traveling wave tube, as an important member of the electric vacuum device family, has the characteristics of high power and wide band. It has a wide application prospect in millimeter wave radar, millimeter wave communication and electronic warfare. However, when the gyrotron works in W or more high frequency section, if the working mode still uses the low order mode such as TE11 or TE01, the high frequency size will be smaller. The problem is that the power capacity of the tube is limited, the electronic interception is easy to happen and the processing is difficult. The high order mode as the working mode of the gyrotron can effectively solve this problem. Therefore, it is of great significance to study the high order mode gyrotron. The next two aspects of research work: first, the high frequency interaction structure of gyrotron with TE12 mode as the working mode and the input and output system are studied. Two is the study of the low / high order mode exciter commonly used in the gyrotron. The main research contents and results are as follows: the second chapter is based on the TE12 mode. The high frequency structure of the gyrotron for the working mode is designed and studied. First, based on the small signal theory, the working mode TE12 and the TE41 mode which almost coincide with the TE12 mode dispersion curve are calculated. The calculation shows that when the magnetic field is 0.988 times of the tangent magnetic field, the vibration current of the TE12 and TE41 mode reaches more than 10A. Therefore, when the working current is 10A, it can ensure that the two modes do not have absolute instability. Based on the small signal theory, the lossless vibration length of the mode of the possible back wave oscillation with the electron cyclotron mode dispersion curve to the KZ negative semi axis is also calculated, and the corresponding loss values of the modes when the mode length reaches 20cm are required. Then based on the results of the small signal theory, the loss of the material to each mode is simulated and analyzed, and a high frequency structure which can work steadily is determined. Finally, the influence of the length, voltage and magnetic field of the smooth section on the high frequency output is analyzed. The third chapter is on the input and output system of the TE12 mode gyrotron. A single Y branch Bragg reflector type input coupler is designed. Two kinds of Bragg reflectors are designed for the same single Y branch structure. The problem of the traditional cut-off waveguide is too small at high frequency, and a input coupler with rectangular corrugated waveguide Bragg reflector is processed and tested. In order to further improve the input coupler, the input coupler is further improved. A double twist Y branch input coupler structure is proposed. The simulation results show that the transformation of the TE12 mode of the single Y branch structure is increased from about -1dB to about -0.5dB. The design middle layer of the output window is sapphire, the thickness is 1mm, the thickness of the matched quartz is 0.42mm, and the simulation and theoretical calculation show that the bandwidth meets the design requirements. The thermal analysis results show that the windows can work effectively, and finally the single layer sapphire windows are processed and tested. The fourth chapter is a study of the mode exciter commonly used in the gyrotron. First, a new type of exciter which can stimulate the TE0n/TE2n/TE1n'mode is proposed. The design idea is rectangular TE10 to rectangle TEn'0 to circular waveguide TE0n/TE2n/ TE1n'. the mode exciter can stimulate low order / high order mode, compact structure, easy processing, high mode purity and wide bandwidth. On the basis of our proposed structure, a low order TE01 mode exciter, TE01/TE21 mode exciter (the same topology), and a high order TE13 mode exciter are designed and tested. A high order TE12 mode exciter is designed to be used in the TE12 mode high order mode gyrotron. Finally, a high order mode TE13 mode input coupler is designed and tested. Compared to the competition mode of the TE13 mode input coupler of the TE12 mode input coupler, the slotting of the side wall of the waveguide wall is put forward. The idea, which destroys the electric field structure of the competition mode, inhibits the formation of the competition mode and improves the conversion efficiency of the design mode. The study of the gyrotron using the high order mode can avoid the problem of the limited power capacity and processing difficulties in the W band or the more high frequency section when the low order mode is used. The research is of great significance for the cold test and thermal test of gyro TWT.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN124

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