圆柱开槽波导的FEM放大器数值研究

对圆柱开槽波导、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,导出了自治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。     

毫米波圆柱波导自由电子激光放大器的数值模拟

本文以单粒子理论为基础，在不计空间电荷效应的近似条件下推导了带轴向引导磁场的三维圆柱波导非线性模拟方程组。用CAGFEL程序计算、分析了在带入口区、常数摇摆器条件下两组不同物理参数的自由电子激光放大器的物理模型。计算结果可靠，物理图象合理。对于其中的第二组参数还着重考查了光波频率、输入功率和摇摆器场振幅改变对输出功率和效率的影响。上述这些计算结果对0．7MeV 自由电子激光放大器的设计和实验具有一定的参考价值。     

高次谐波开槽回旋行波放大管自洽非线性数值模拟

:在未考虑电子注速度零散、引导中心零散以及波导壁损耗的情况下,采用四阶龙格库塔法,对均匀截面开槽高次回旋行波放大管注波互作用进行了数值计算,得出一些重要的互作用规律。电子注绕轴作大回旋运动。在π模式、四次谐波、35.05GHz、58kV、8A、v⊥/v∥＝1.5的情况下,饱和效率达到24.4%,增益为34dB,峰值功率为113.2kW,饱和带宽为4%。     

高次谐波开槽回旋行波放大管自洽非线性数值模拟

 :在未考虑电子注速度零散、引导中心零散以及波导壁损耗的情况下,采用四阶龙格库塔法,对均匀截面开槽高次回旋行波放大管注波互作用进行了数值计算,得出一些重要的互作用规律。电子注绕轴作大回旋运动。在π模式、四次谐波、35.05GHz、58kV、8A、v⊥/v∥＝1.5的情况下,饱和效率达到24.4%,增益为34dB,峰值功率为113.2kW,饱和带宽为4%。     

外开槽同轴波导大轨道回旋自谐振脉塞放大器

运用大轨道电子束,对外开槽同轴波导回旋自谐振放大器进行了线性动力学理论分析和非线性自洽模型模拟。由线性动力学理论分析和非线性模拟得到的结果在线性增长部分吻合得很好。为了有效抑制绝对不稳定性,对电子束流的选择进行了讨论。计算结果表明：对于电压为700 kV, 电流为100 A, 电子束纵横向速度比为0.8的大轨道电子束, TE51外开槽同轴波导回旋自谐振脉塞放大器的峰值功率和峰值效率分别可以达到6.27 MW和8.96%。     

外开槽同轴波导大轨道回旋自谐振脉塞放大器

 运用大轨道电子束,对外开槽同轴波导回旋自谐振放大器进行了线性动力学理论分析和非线性自洽模型模拟。由线性动力学理论分析和非线性模拟得到的结果在线性增长部分吻合得很好。为了有效抑制绝对不稳定性,对电子束流的选择进行了讨论。计算结果表明：对于电压为700 kV, 电流为100 A, 电子束纵横向速度比为0.8的大轨道电子束, TE₅₁外开槽同轴波导回旋自谐振脉塞放大器的峰值功率和峰值效率分别可以达到6.27 MW和8.96%。     

外开槽同轴波导传播特性

 根据满足边界条件的一系列电磁场方程,采用场匹配法,详细推导了外开槽同轴波导的特征方程。在外开槽同轴波导光滑内同轴半径等于零的情形下,即变成外开槽圆波导,得到其特征方程。数值模拟了外开槽同轴波导及外开槽圆波导中TE₀₁模式的传播特性,得到了不同尺寸外开槽同轴波导开槽间隙半张角和槽深与特征根的变化关系。结果表明:开槽越深,间隙半张角越小,特征根值越小。     

有限磁场中等离子体圆柱波导的传播特性

分析了有耗介质中等离子体圆柱波导在有限外加磁场中的传播特性.重点讨论了波导传播常数随等离子体参数、介质参数和外加磁场的变化.分析结果表明，有限强磁场中的等离子体波导的传播特性比无外磁场或外加磁场为无穷大时具有更强的控制能力. 关键词：     

内外开槽同轴潘尼管波导传播特性

推导了内外开槽同轴波导和外开槽圆波导的特征方程。数值模拟了内外开槽同轴波导及外开槽圆波导中2π模式的传播特性,研究了开槽深度与截止波数的关系及内外开槽潘尼管频率与各个半径之间的关系。结果表明：内外开槽同轴波导的特征值随内开槽深度的增加而增大,随外开槽深度的增加而减小;内槽半径对频率的影响很小,外槽半径起主要作用。     

椭圆波导FEM放大器的非线性特性研究

以椭圆波导、平板摇摆器为FEM放大器的模型,导出了自洽的注波互作用三维非线性方程组。在此基础上编制了相应的程序。利用该程序分析了FEM放大器的饱和功率、效率以及带宽等高频特性。考虑了摇摆器渐变、空间电荷波、电子初始速度零散对高频特性的影响。     

Nonlinear Analysis on FEM Amplifier with Circular Groove Guide

FEM amplifier with a novel circular groove guide is proposed and researched both in three-dimensional nonlinear theory and numerical computation in this paper. Efficiency and bandwidth of the FEM are studied including electron beam emittance.     

Attenuation Characteristics of Corrugated Circular Groove Waveguide

When neglecting space harmonics and higher-order slot modes, the attenuation characteristic of corrugated circular groove waveguide has been investigated. It is shown that under certain conditions, the attenuation coefficient of HE ₁₁ mode will be lower than that of dominant TE ⁽¹⁾ ₁₁ mode of circular groove waveguide with same radius.     

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.     

Design of a Rectangular to Circular Groove Waveguide Transition by Finite Element Method

A rectangular to circular groove waveguide transition is described in millimeter-wave band. The transition maintains a constant cutoff wavelength. Using the Finite Element Method, the size of the variable cross-section throughout the transition are calculated and the transition is designed.     

Nonlinear Study on FEM Amplifier with a Novel Elliptic-Groove Guide

FEM amplifier with a novel elliptic-groove guide is proposed and three-dimensional nonlinear theory for the elliptic-groove guide FEM amplifier is developed. A set of coupled nonlinear differential equations is derived and the characteristics of this FEM amplifier are numerically analyzed in detail including the evolution of power, efficiency and bandwidth. The effects on saturation efficiency due to electron momentum spread and wiggler taper are also studied.     

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.     

Nonlinear Analysis of Elliptical Waveguide FEM Amplifier

A set of nonlinear three-dimension equations for the FEM amplifier with elliptical waveguide and planar wiggler is derived. Based on these equations, a universal numerical simulation program is developed independently. The characterisitics of this FEM including the evolution of power, saturation efficiency and bandwidth are investigated. Electron momentum spread and wiggler taper are also considered.     

掺铒聚合物光波导放大器的数值分析

针对掺铒聚合物光波导放大器(EDWA),提出了一种基于Douglas离散格式改进的有限差光束传播法(FD-BPM)的数值计算方法。对每一传输步长结合多能级速率方程计算出EDWA中光场传输强度分布,及掺铒光波导放大器的增益传输特性。设计并研究了掺铒聚合物通道波导和Y形分束器的放大增益特性。在掺铒聚合物直波导中,Er3 浓度为9.0×1025ions·m-3,输入信号和泵浦光功率分别为1μW和2mW,其增益为1.6dB/cm;在掺铒聚合物Y形分束器中,输出信号光分束比相等,并能实现无损耗分束。     

Analysis for a Novel Cocoon-Shaped Groove Guide with Method of Lines

An arbitrarily cross-sectional groove guide is analyzed by using the method of lines and its characteristic equations are gives for TE and TM modes. Some numerical results show that correctness of the method of lines compared with the relevant results in the references is verified, and it is convenient to solve groove guide with arbitrary shape in practical application problems. A novel cocoon-shaped groove guide is firstly presented and its transmission characteristics are analyzed and discussed. The new type of cocoon-shaped groove guide has the good performances. The obtained results are of important application values in theoretical studies and practical applications of groove guides for millimeter waves.     

Dual-Core Leaky Waveguide-Based Filters for Erbium-Doped Waveguide Amplifier

Abstract

This article gives the design of a gain-flattening filter for an erbium-doped waveguide amplifier using a dual-core resonant leaky waveguide. The spectral variation of leakage loss of the waveguide has been used for gain equalization of the erbium-doped waveguide amplifier in the conventional (C) band. Leakage loss of the structure has been calculated by using the transfer matrix method. Numerical simulation results show a 17.5-dB gain with a gain excursion of ±1.35 dB in the C-band (1,526 nm–1,566 nm) of a typical erbium-doped waveguide amplifier. The study should be useful in designing integrated optic gain-flattening filters.