【作者】 王少萌；

【导师】 宫玉彬；

【作者基本信息】 电子科技大学 ， 物理电子学， 2013， 博士

【摘要】 径向束行波管是行波管中重要的一类管型，具有宽频带、低电压及小尺寸的重要特点，在卫星通讯、雷达系统等对器件体积重量要求较高的军事领域以及民用领域都有很好的发展和应用前景。为满足现代军事对抗对低电压、小体积的微波放大器件的需求，拓展行波管的应用领域，提高行波管的竞争力，开展对径向束行波管的研究具有十分重要的意义。本论文深入分析研究了径向带状电子束的产生、聚焦及与慢电磁波互作用的机理，并在此基础上提出了一种新型慢波系统，为解决径向束行波管在毫米波段的工作难题提供了新的途径。论文的重要工作和创新点总结如下：1．给出了径向电子光学系统的设计方法，以及径向电子束聚焦的布里渊磁场的计算方法。在此基础上详细研究了径向带状电子束的产生、传输和聚焦方式，包括新型圆柱侧面发射阴极、环形阳极和径向磁场等。并分别设计了阴极在内、收集极在外的发散型和阴极在外、收集极在内的收敛型电子光学系统。2．提出了非周期慢波系统的色散特性和耦合阻抗的计算方法，并将之应用于对数螺旋线慢波系统的研究。分析了对数螺旋线慢波系统的互作用机理，设计了工作电压在30V的微带型平面对数螺旋线行波管，研究了其色散特性和耦合阻抗随结构参数的变化，并通过粒子模拟的方法得到了注波互作用图像，得到了其功率随输入电流和频率的变化曲线，当输入功率40mW时，计算得到了127mW的输出功率，在S波段的3-dB带宽达3GHz。3.提出了波导型对数螺旋线径向行波管的概念，以克服微带型平面对数螺旋线慢波系统的工作电压过低、电流偏小以及工作频段较低等缺点，并对其传输特性、色散特性和耦合阻抗进行了研究，研究表明该结构具有应用于W波段径向束行波管的潜力。4.引入了平面角度对数曲折线慢波系统的新概念，它具有结构简单、易加工、小型化和便于集成等特点。这种结构是对数螺旋线慢波系统的改进型结构，最大的优点是可以工作在更高的工作频段；另外，不同的角度，对应的工作电压可以低至百伏以内，也可以高至数千伏，这样在相同的直流输入功率下，所需的电子束电流更小，从而避免了对数螺旋线慢波系统对电子注电流必须很大的限制，使阴极的工作寿命更长。采用这种慢波系统分别设计了工作电压为1600V采用收敛电子束和工作电压为800V采用发散电子束的Ka波段行波管，两者的峰值输出功率分别为160W和27W，3-dB功率带宽分别为71.4%和80%，互作用效率分别达到了19.7%与21.7%，前者具有更高的工作电压，因此可以给出更高的功率输出，而后者则具有更充分的互作用，因此具有更高的效率和增益。5.为了提高微带角度对数曲折线慢波系统的输出功率，本文提出了角向集成微带角度对数曲折线慢波系统的概念。采用这种慢波线系统的行波管可以获得与常规行波管差不多的功率输出（数百甚至上千瓦），在带宽和工作电压上也具有一定的优势；同时，角向集成微带角度曲折线慢波系统采用完整的径向带状电子束工作，因此较单根微带角度对数周期曲折线慢波系统更易于实现电子束的聚焦。6.为了充分发挥平面角度对数曲折线的应用潜力，本文研究了镜像对称的双角度对数曲折线慢波系统，并分别研究了工作电压在800V、工作频段在Ka波段的、采用径向收敛和发散带状电子束的行波管的注波互作用特性。模拟结果表明：采用径向收敛带状电子束时，可以在20~50GHz的频率范围内输出大于30W的功率，最大功率为55W，最大效率可达26%；而采用发散束的行波管，可以在20~45GHz的频率范围内输出大于40W的功率，最大功率为64W，最大效率和增益分别为26.3%和19.5dB，这两种行波管的性能均优于单层的微带平面角度对数曲折线行波管。7.详细研究了微带型角度对数曲折线慢波系统的传输特性，包括参数变化对反射与传输参量的影响、介质和导体材料对慢波系统的损耗的影响、以及慢波系统中主要损耗之间的对比等；设计了采用标准同轴连接器的微带角度对数曲折线慢波系统的输入输出结构，实验加工了工作频率在12GHz的慢波系统，在11~13.5GHz的频率范围内，其反射系数数S11小于-10dB，传输损耗大于-1.5dB，驻波系数小于2。在此基础上，对实验模型进行了改进，设计了18GHz的微带角度曲折线，测试表明：其反射系数S11在13~22GHz的频率范围内小于-15dB，损耗S21大于-2.9dB.更多还原

【Abstract】 Being one of the important traveling wave tubes (TWTs), the radial sheet beamTWT has a good development and application prospect in satellite communication,radar systems, for its wide bandwidth, low operating voltage and small size. To meetthe needs of low voltage, small size microwave amplifiers, expand the applicationfields and increase the competitiveness of TWT, it is important to study the radialTWT.The production, focusing and beam wave interaction of radial sheet electron beamare researched in this paper, and based on this, a kind of novel slow wave structure(SWS) has been proposed, which supplying a new way to solve the TWT’s problems.The main work and innovation of this dissertation are as follows:1. The design method of radial electron optical system is given, and based on this,the production, transmission and focusing of the radial sheet electron beam are studiedin detail.The Brillion focusing magnetic for radial sheet beam is obtained from theMaxwell and Lorenz equations. And two kinds of radial optical systems are designed,that are the divergent type with cathode inside the anodes and the convergent type withcathode outside the anodes.2. The calculation methods of the non-periodic SWS’s dispersion characteristicand coupling impedance are proposed, and they were used to the logartithmical helixresearch.The beam wave interaction mechanism of this kind SWS is studied, and themicro-strip type radial logarithmical helix SWS with operating voltage30V isdesigned. Its dispersion characteristic curve and coupling impedance are obtained. Theparticle-in-cell (PIC) simulation results show that it can give an127mW output powerwith the input power40mW, and its3-dB operating bandwidth is about3GHz at Sband.3. To overcome the disadvantages of the micro-strip logarithmical helix, such asthe small operating voltage and current, the low frequency band, the waveguide typelogarithmical helix is proposed. Its dispersion characteristic and coupling impedanceare studied, and the results show that it can be used for W band radial TWT.4. A novel angular log-periodic meander line SWS, with a simple structure andsmall size, is introduced in this dissertation. Improved from the logarithmic helix, thiskind of SWS can work at a higher frequency. Moreover, the operating voltage istunable from hundreds to thousands Volt for different angles. So its beam current could be smaller than the logarithmic helix needed for the same direct current input power.Two TWTs with radial convergent and divergent sheet electron beam, whose operatingvoltages are1600V and800V respectively, are designed with this kind of SWS. Themaximum output power is160W and26W correspondingly, and the bandwidth is71.6%and80%with electron efficiency19.7%and21.7%.5. To increase the output power of this kind of SWS, the conception of angularintegrated angular log-periodic meander line SWS is proposed. The TWT with thiskind of SWS can give an output power as large as the conventional TWTs, and is betterat the bandwidth and operating voltage. Meanwhile, the electron beam of this kindTWT is easier to focus than the single angular log-periodic meander line TWT.6. The symmetric double angular log-periodic meander line SWS is studied toexplore the potential amplifying ability. Both the convergent and divergent electronbeams are studied with the same operating voltage800V. With a radial convergentsheet beam, this kind of TWT can give a maximum output power55W, with the3-dBbandwidth over20~50GHz and the biggest efficiency26%. While for the divergentelectron beam, an output power more than40W over the20~45GHz is abtained, andthe maximum efficiency and gain are26.3%and19.5dB respectively.7. The transmission and reflect characteristics of the angular log-periodic meanderline SWS are studied in detail. The transmission loss for different metals anddielectrics are calculated. The input and output structures for the angular log-periodicmeander line slow wave structure is designed, and the SWS with operating frequency12GHz is fabricated and tested, the S11less than-10dB, S21larger than-1.5dB andthe voltage stand wave ratio less than2are obtained. Based on the results, a new inputand output structure is designed, and is applied to the18GHz SWS. The experimentresults show that the S11is less than-15dB and S21larger than-2.9dB between thefrequency13~22GHz.更多还原