等离子体填充盘荷波导高频特性分析

从麦克斯韦方程和流体理论出发，推导了填充磁化等离子体慢波结构的基本方程.在大磁场情况下，对等离子体填充盘荷波导的色散特性和耦合阻抗作了研究，结果表明填充等离子体使色散曲线上移，耦合阻抗提高.等离子体填充产生出模式谱非常丰富的周期性低频等离子体模式(TG模式).当等离子体密度增加到一定程度后，场模TM₀₁模的频率范围和TG₀₁模的频率范围相近，两个模式互相耦合产生出新的混合模G₁,G₂.如果相对论行波管工作在混合模上，将会产生新的工作机理. 关键词： 盘荷波导 等离子体填充 色散特性 相对论行波管     

等离子体部分填充的波纹慢波结构中电磁波色散特性

对有限厚环形等离子体层填充的波纹慢波结构中电磁波色散特性进行了分析。研究结果表明,对于ω＞ωp的高频TM0n模,模式色散曲线随等离子体密度的增加而上移;ω≤ωp的低频等离子体模为一系列呈周期变化的密度谱,部分模式能与电子注发生较强的同步互作用。等离子体模的时间增长率随等离子体密度的增加快速增加,而TM0n模则快速减小或缓慢增加,因此在较高的等离子体密度下,高频模式可能被抑制。     

等离子体部分填充的波纹慢波结构中电磁波色散特性

 对有限厚环形等离子体层填充的波纹慢波结构中电磁波色散特性进行了分析。研究结果表明，对于ω＞ω_p的高频TM_0n模，模式色散曲线随等离子体密度的增加而上移；ω≤ω_p的低频等离子体模为一系列呈周期变化的密度谱，部分模式能与电子注发生较强的同步互作用。等离子体模的时间增长率随等离子体密度的增加快速增加，而TM_0n模则快速减小或缓慢增加，因此在较高的等离子体密度下，高频模式可能被抑制。     

纳米金属肋混合表面等离子体波导模式特性分析

基于传统混合表面等离子体波导,提出了一种半导体纳米线和纳米金属肋混合的表面等离子体波导.采用有限元法对其模式特性进行了数值模拟,研究了该波导的有效折射率、传播损耗、归一化模场面积等特性随波导几何尺寸的变化规律,分析了该混合波导的增益阈值.结果表明:该波导具有较低的传播损耗和较强的光场限制能力,并且混合模式的最小模面积仅为0.001 52μm2.     

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。     

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。     

基于螺旋波纹波导高增益高效率被动式压缩方法

对一种改进型螺旋波纹波导实现高增益高效率被动式脉冲压缩进行了研究,并利用微扰理论求解出了该波导的损耗特性。结合波导的色散和损耗特性,设计了输入微波的频率调制形式。还对改进型螺旋波纹波导进行了模拟研究,在输入脉冲宽度为66 ns的条件下,得到了半高宽为1.9 ns的压缩脉冲,增益为21.2倍,脉冲宽度比为34.7倍,压缩效率为61%,这表明改进型螺旋波纹波导应用于被动式脉冲压缩具有高效率高增益特性。     

梯形截面硅脊形波导的模式特性及其等离子体色散效应

本文运用有效折射率法和WKB法对具有梯形状截面的硅脊形波导的模式特性作了分析,导出了TE模和TM模的模方程以及截止方程,并运用一阶微扰法对因波导顶部注入载流子而引起的模式调制的大小作了数值估计。其结果可为全硅光波导器件的研制提供指导。     

螺旋波纹波导研究

从耦合波方程出发，利用阻抗微扰法对螺旋波纹波导的边界不规则性进行处理，得到螺旋波纹波导的一般性耦合波传输方程，及耦合系数表达式.根据螺旋波纹波导内模式耦合的规则,得出色散方程并分析其色散特性. 关键词： 螺旋波纹波导 耦合波方程 阻抗微扰 色散特性 本征模     

同轴波纹返波管色散特性研究及粒子模拟

计算了同轴波纹慢波结构的色散特性,分析了波纹周期长度、波纹幅值大小以及同轴内导体半径对慢波结构色散特性的影响。研究表明内导体的存在使系统截止频率升高,系统尺寸可比普通波纹波导慢波系统更大, 并且可以采用大半径电子注并工作在低磁场状态。运用Magic软件对同轴波纹返波管进行了数值模拟, 发现同轴波导内场分布有利于注波互作用,在数值模拟基础上设计出高效率、低磁场的非均匀同轴波纹返波管,互作用效率达60%,聚束磁场小于1 T。     

A novel numerical synthetic technique for determination of the TMon dispersion relation in a coaxial corrugated cylindrical waveguide

A novel, highly accurate numerical synthetic technique for determining the complete dispersive characteristics of electromagnetic modes in a spatially periodic structure is presented. The numerical method based on the coupling of the finite difference method in time domain with the discrete fourier transform is applied to calculate the eigenfrequencies and eigenfield distribution of a resonant cavity which is an appropriately shorted periodic slow wave circuit of N periods at both ends. The analytical synthetic technique, which is based on the intrinsic characteristic of spatially periodic structure, is used to derive the complete dispersion relation using the numerically measured resonances. The method was successfully applied for the case of TM_on modes in a coaxial corrugated waveguide and is applicable to slow wave structures of arbitrary geometry.     

等离子体填充圆柱波导中双流不稳定性的研究

在无限大磁场情况下对等离子体填充圆柱波导中双电子注的相互作用进行了理论分析,得出行列式形式的色散方程。针对不同参数对色散方程进行数值计算,发现当两根电子注之间存在速度差时,通过快慢空间电荷波的相互作用,两电子注引起的双流不稳定性可以产生契伦柯夫辐射;当等离子体频率超过双注相互作用的频率范围后,可以大大加强和改善等离子体、两电子注三者之间的相互作用。     

“Cold” dispersion relation of corrugated waveguide filled with plasma immersed in a finite magnetic field

A general dispersion equation of a partially filled plasma corrugated waveguide immersed in a finite magnetic field is presented. When the guiding magnet B_0→∞ or 0, this equation can be reduced to the results obtained in previous works.     

Excitation of surface plasma waves over corrugated slow-wave structure

A microwave propagating along vacuum—dielectric—plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between dielectric and slow-wave structure. These slow SPW can couple the microwave energy to the plasma and can sustain the discharge. The efficiency of the power coupling is few per cent and is sensitive to separation between dielectric and slow-wave structure.     

Theory of electromagnetic wave propagation in a plasma-filled corrugate waveguide immersed in a finite magnetized field

The linear theory of electromagnetic radiation from a high-power backward-wave-oscillator (BWO), travelling-wave-tube (TWT) with plasma-filled, sinusoidally corrugate waveguide driven by an intense relativistic electron beam (IREB) has been derived and analysed numerically. A general dispersion relation is presented for analysing a plasmafilled corrugate waveguide immersed in magnetized plasma in this paper. It is shown that the linear theory developed here is in good agreement with the previous work.     

Theoretical study of wave propagation along the coaxial waveguide filled with moving magnetized plasma

This paper presents detailed theoretical study on the theory of wave propagation along the coaxial waveguide filled with moving magnetized plasma (CWMMP). Making use of the Lorentz transformation and the constitutive transformation, Maxwell’s equations lead to the coupled non-homogeneous differential equations which govern the wave propagation in CWMMP, and then analytical solutions have been obtained. The discussion about the eigenvalues of the waves and detailed studies on the fields are carried out. It finds that the fields of the CWMMP are composed of two parts with different eigenvalues. Numerical calculations show that because of Doppler shift effect, the eigenvalues of the modes in such a case is quite different from those of the CWMMP. And a detailed discussion on the dispersion characteristic of CWMMP is presented.     

高功率微波在等离子体填充波导中的谐波产生

采用等离子体流体理论，研究了高功率微波在等离子体填充波导中的谐波产生，导出了非线性波动方程. 对二次谐波产生进行了数值计算与分析. 理论分析和数值计算表明，高功率微波将在等离子体填充波导中激发起谐波，TE_0n模式与TM_0n模式的基波都将激发起TM类型的谐波. 关键词： 高功率微波 谐波产生 等离子体填充波导     

Theoretical analysis of a relativistic travelling wave tube filled with plasma

A cold and uniform plasma-filled travelling wave tube with sinusoidally corrugated slow wave structure is driven by a finite thick annular intense relativistic electron beam with the entire system immersed in a strong longitudinal magnetic field. By means of the linear field theory, the dispersion relation for the relativistic travelling wave tube (RTWT) is derived. By numerical computation, the dispersion characteristics of the RTWT are analysed in different cases of various geometric parameters of the slow wave structure and plasma densities. Also the gain versus frequency for three different plasma densities and the peak gain of the tube versus plasma density are analysed. Some useful results are obtained on the basis of the discussion.