螺旋槽回旋行波管高频特性分析

 在Foulds等人对螺旋槽结构进行深入分析的基础上,考虑了槽区内高次模式对慢波结构高频特性的影响。结果表明：槽宽较小时,结论与其结论吻合较好; 槽宽较大时,计算结果与其有较大差别。此外,讨论了螺旋槽结构参数对高频特性的影响,结果表明：除槽宽外的其它结构参数固定时,存在一个最佳的δ/L值,可以获得较弱的色散和较大的横向场幅值,适合做回旋行波管互作用结构。     

The Analysis of Hole-Gap Helical Groove Waveguide

The hole-gap helical groove waveguide, as a all-metal slow-wave circuit, has advantages of good heat dissipation and great size, and thus is suitable for use of mm TWT. By means of an approximate field theory, the expressions of the dispersion equation and the coupling impedance of the hole-gap helical groove waveguide is obtained in this paper. The influence of various circuit dimensions on the dispersion relation and the coupling impedance is discussed by the numerical computation.     

Wave Propagation Along a Helical Step-Loaded Groove Waveguide

A new kind of helical groove structure, step-loaded groove waveguide is presented and analyzed in this paper. The dispersion equation of this structure is derived by means of a field-matching method. This equation may be reduced to the dispersion equation of helical ridge-loaded structure and rectangular one. In order to demonstrate the influence of the step on the dispersion properties, the comparison of the dispersion characteristics is made in these helical rectangular and modified rectangular groove structures. Form the analysis, it is shown that the step loading tends to reduce the dispersion of the helical groove circuit and the step-loaded structure has the weaker dispersion compared with the rectangular one or the ridge-loaded one. The effect of the step shape on the wave properties is also discussed under the deep groove case. The theoretical results explicitly indicate that the V-like step-loaded structure has the weakest dispersion in all step-loaded structures.     

Analysis of the Coaxial Ridge-Loaded Helical Groove Waveguide

The coaxial ridge-loaded helical groove waveguide is proposed in this paper. As an all-metal slow-wave circuit, it has advantages of good heat dissipation and great size, and thus is suitable for use of millimeter TWT. By means of field theory, the expressions of the dispersion equation and the coupling impedance of the coaxial ridge-loaded helical groove waveguide are obtained. The influence of various circuit dimensions on the dispersion relation and the coupling impedance is investigated by the results of numerical computation.     

Dielectric effect on the rf characteristics of a helical groove travelling wave tube

A new type of partial-dielectric-loaded helical groove slow-wave structure (SWS) for millimetre wave travelling wave tube (TWT） is presented in this paper.The radio-frequency characteristics including the dispersion properties,the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analysed.The results show that the dispersion of the helical groove circuit is weakened,the phase velocity is reduced and the position of the maximum Ez is moved from the mouth to the inside of the groove after partially filling the dielectric materials in the helical groove SWS.Therefore,the dielectric-loaded helical groove SWS is suitable for a multi-beam TWT with broad band and high gain.     

The Small Signal Analysis of a Centered Dielectric-Rod Loaded, Arbitrarily-Shaped Helical Groove Traveling-Wave-Tube

Properties of traveling wave-beam interaction in a centered dielectric-rod loaded, arbitrarily-shaped helical groove slow-wave structure (SWS) are investigated for a thin annular electron beam. The “hot” dispersion equation is obtained by means of the self-consistent field theory, and the small signal analysis is carried out including the effects of the dielectric-rod parameters and the groove shapes. The numerical results show that the bandwidth of the helical groove TWT is expanded by loading dielectric-rod, however, the small-signal gain is reduced; and when the groove shape changes from the swallow-tail shape to the triangle shape, the working frequency increases , while the peak gain decreases. Project supported by the National Nature Science Foundation of China (Granted NO.60401005 and 60532010).     

同轴任意槽形周期圆波导慢波结构色散特性的研究

用阶梯近似的方法分析任意槽形加载的圆波导慢波系统，利用各阶梯相邻面的导纳匹配条件 以及中心互作用区与加载区的场匹配条件，获得了任意槽形加载周期慢波结构的统一色散方 程. 利用该色散方程，得到色散特性与CST MWS仿真软件模拟结果良好符合. 分别求解几种 特殊槽形加载慢波结构的色散特性及耦合阻抗，其中，三角形结构色散和耦合阻抗均最弱， 而倒梯形结构色散最强，耦合阻抗最大. 关键词： 任意槽形 慢波结构 色散特性 行波管     

具有任意槽的矩形波导栅慢波结构高频特性的研究

将任意形状槽的连续轮廓近似用一系列相连的矩形阶梯近似，利用各阶梯面上导纳的匹配，以及槽与互作用区边界场的连续与匹配条件，获得了具有任意槽的矩形波导栅慢波结构的色散方程和耦合阻抗的表达式，并进行理论上的验证.加工制作了矩形槽波导栅模型，冷测表明理论值与测量值相吻合.分别求解几种特殊槽形矩形波导栅慢波结构的色散特性及耦合阻抗，其中，三角形结构的色散和耦合阻抗均最弱，而倒梯形结构色散最强，耦合阻抗最大. 关键词： 矩形波导栅 任意槽 色散特性 慢波结构     

Linear Theory of the Coaxial Ridge-Loaded Helical Groove Waveguide

The coaxial ridge-loaded helical groove waveguide, an all-metal slow-wave circuit, has advantages of good heat dissipation and great size, and thus is suitable for use of millimeter TWTs. In this paper, the dispersion equation of the circuit with an annular electron beam is obtained according to self-consistent field theory. The influence of various electron beam parameters on the small signal gain is investigated and discussed by the numerical computation.     

Dispersion Characteristics of Coaxial Circular-Arc-Groove Slow-Wave Structure

The coaxial circular-arc-groove periodic slow-wave system for relativestic traveling wave tubes (RTWT) is presented in this paper. To analyze the field in the groove region, the continuous profile of the circular arc is approximately replaced by a series of rectangular steps and the field continuity at the neighboring steps is deduced. The dispersion equation of the coaxial circular-arc-groove slow-wave structure is derived by the matching conditions at the interface between the groove region and central region. The influence of various circuit parameters on the dispersion relation is investigated by the numerical calculation.     

ANALYSIS OF RECTANGULAR WAVEGUIDE GRATING SLOW-WAVE STRUCTURE WITH THE ARBITRARY SHAPED GROOVES

The rectangular waveguide grating slow-wave structure (SWS) with arbitrary shaped grooves is presented and analyzed in this paper. As an all-metal slow-wave circuit, it has properties that can be used in high-power millimeter-wave or sub-millimeter wave traveling wave tube (TWT). The unified dispersion equation and the expression of coupling impedance are obtained in this paper by means of an approximate field-theory analysis, in which the profile of the groove is approximately replaced by a series of steps and the field continuity at the interface of two neighboring steps together with the field matching conditions at the interface between the groove region and the interaction region are employed. A rectangular groove SWS was manufactured and the cold measurement was made. The experimental data are in good agreement with the numerical calculation. The derived transcendental equations are resolved numerically for four classical structures such as rectangular, dovetail, ladder and cosine. Finally, taking the rectangular waveguide grating SWS with rectangular grooves for example, the influences of physical dimensions on dispersion relation and coupling impedance are discussed.     

Investigation of the Half-Circular Helical Groove Slow-Wave Structure

As a new type all-metal slow-wave structure of the millimeter wave TWT, The helical groove has a lot of advantages: large power handling capability, large sizes, high precision and moderate bandwidth. Of the helical groove structure, the half-circular helical groove can achieve wider passband than the rectangular helical groove can do. The approximate and much simple matching method of the fields of the half-circular structure is presented in this paper. The more general expressions of the dispersion characteristic and coupling impedence, in which the fast-wave modes and slow-wave modes are considered simultaneously, are obtained. It is indicated from the results of the numerical calculation that choosing suitable dimensions of the structure and suppessing the backward wave osillation, this kind of slow-wave structure can operate over 50% hot relative bandwidth.     

Investigation of the Dielectric-Loaded, Ridged Helical Groove Slow-Wave System for the Millimeter Wave TWT

A dielectric-loaded, ridged helical groove slow-wave structure for the millimeter wave traveling wave tube is presented in this paper. The effects of the groove depth, ridge dimensions and the dielectric permitivety on the wave propagating properties and the interaction impedance are investigated in detail. From the analysis, it is indicated that for broader band amplification in a helical groove travelling wave tube, a ridged helical structure with shallow groove and loaded by dielectric with proper relative permitivety may be applied.     

Analysis of Loss and Dispersion Characteristics for Groove Guides with Arbitrary Groove Profiles by an Equivalent Active Transmission Line Method*

Loss and dispersion characteristics of groove guide are two practically important factors in the design for millimeter wave system consisting of groove guide. In this paper, a new method is presented for analyzing loss and dispersion characteristics of the groove guides with arbitrary groove cross-sections. The method is based on the combination of an equivalent active transmission line equation and the staircase approximation. Numerical results of dispersion and attenuation properties for some groove guides with different groove profiles are given. The effectiveness and practicality of the present analysis are confirmed by the data given in the literature.*Supported by the National Natural Science Foundation of China (No. 60171019) and (No. 60371010)     

圆柱开槽波导FEM放大器数值研究

以圆柱开槽波导、螺旋摇摆器为模型,考虑了电子初始速度零散、引导磁场等效应对放大器饱和特性的影响,导出了自洽的注波互作用三维非线性方程组.并在此基础上编制了相应的计算软件,通过数值分析的方法研究了圆柱开槽波导自由电子激光放大器的饱和效率、频带宽度等高频特性.     

正弦波导高频特性分析

对一种全金属慢波系统—–正弦波导的高频特性进行了理论分析.在用一系列相连矩形阶梯逼近余弦槽的基础上,对慢波结构进行了合理的区域划分,获得了各区域的场表达式.考虑槽区的高次驻波项,采用场匹配和导纳匹配相结合的方法,导出色散方程和耦合阻抗表达式.以应用于220 GHz行波管的正弦波导为例进行高频特性的数值求解,理论计算值与全三维电磁软件CST-MWS的仿真值符合良好.在此基础上,详细分析了尺寸参数变化对正弦波导高频特性的影响.     

Ka波段螺旋波纹波导回旋行波管

螺旋波纹波导回旋行波管与采用圆波导的回旋行波管相比,有较大的带宽。介绍了它的线性注波互作用理论,并用该理论计算了不同的磁场与波导表面微扰幅度对Ka波段螺旋波纹波导回旋行波管线性增益的影响。计算结果与已报道的实验结果基本符合,说明该理论可以初步确定螺旋波纹波导回旋行波管的各项参数。     

磁化等离子体填充螺旋线的色散方程

利用等离子体流体理论和纵向场分量法，结合螺旋线的导电面模型，对在有限磁场作用下，填充等离子体的螺旋线进行了严格的场分析. 在给出各区域电磁场分量表达式的基础上，利用螺旋线的边界条件，导出了磁化等离子体填充螺旋线中电磁波传播所满足的色散方程，并对所导出的色散方程进行了讨论. 关键词： 有限磁场 等离子体 螺旋线 色散方程     

凹面光栅型波长解复用器的标量波动分析

利用标量波动衍射理论，通过对光栅槽面的数值积分，计算了罗兰圆型集成二维凹面光栅像点的光强分布。给出了光线追变法难以得到的光栅槽面沿光栅圆不同方位刻划所引起的成像点对于光栅方程计算位置的偏离；在对色散和分辩力的分析上，获得了与光线追迹法很好的一致性；分析了光栅的槽面波、光源的模场宽度以及因工艺产生的槽面圆角对光栅成像的影响；最后给出了光栅的波像差和光线像差的计算。     

8 mm回旋行波管和返波管的三折螺旋波纹波导色散分析

 三折螺旋波纹波导使TE11模和TE21模相互耦合,其色散曲线能够在宽频带内与电子回旋共振,因此需要对色散方程进行研究。提出了适合工程实用的行波模式和返波模式的色散方程,并对方程中的耦合系数进行了简化,误差在1%左右。利用CST软件的VBA语言对螺旋波纹波导进行建模和计算,根据模拟得到的传输特性曲线的特点,提出一种模拟方法,将模拟与理论计算得到的色散曲线作对比,误差在5%左右。