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1.
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 相似文献
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采用等离子体流体模型和线性场理论,导出了在强引导磁场下,一无限薄环形等离子体加载 波纹波导中电磁波传播的色散关系.数值计算并分析了在不同的等离子体填充密度下,低频 等离子体模式的色散特性和行波管的小信号增益.研究发现,低频等离子体模式可与相对论 电子束发生同步互作用使高频信号放大.同时,在无限薄环形等离子体填充条件下,波纹波 导中的低频等离子体模式严格满足Floquet定理所要求的周期性,其上截止频率不再受到等 离子体频率的限制,当密度较大时,等离子体模式还可与TM模式发生耦合.
关键词:
等离子体
波纹波导
色散关系
增益 相似文献
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高频系统是行波管的核心部件,它会直接影响行波管的工作频率、带宽、增益等性能指标。为了获得更大的输出功率和更高的增益,对0.34 THz双注高次模折叠波导行波管的基本特性进行了研究,计算了双注折叠波导的色散特性和耦合阻抗,并与仿真结果进行对比,结果显示色散特性随频率升高差距增大,耦合阻抗在高频段匹配较好,并研究了损耗特性。利用CST仿真工作室对双注折叠波导的注波互作用特性进行了仿真,实现41.68 W输出。为了获得更高的输出,通过增大直波导高度,最终使输出功率提高了52.7%,达到63.12 W。最后设计了符合要求的盒型输出窗和模式转换器,验证了高频系统的传输特性。 相似文献
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以加载衰减器的螺旋线慢波结构作为研究对象,采用螺旋导电面模型,用真空层模拟螺旋带的厚度,用均匀介质层等效分立的介质夹持杆,并考虑到各横向区域横向传播常数的不同,得到了任意次模式的色散方程和耦合阻抗的表达式. 在此基础之上,分析了衰减器对主模和-1次模式的衰减常数、相位常数和耦合阻抗的影响.所得结果对设计衰减器具有理论指导意义,为螺旋线慢波系统高频特性的改善以及反射振荡和返波振荡的抑制提供了理论依据.
关键词:
螺旋线
行波管
衰减
色散 相似文献
9.
用严格的场匹配方法分析了填充等离子体的耦合腔链,研究了等离子体 腔混合模的形成以及“冷带宽”和“热带宽”的展宽效应。等离子体填充周期性耦合腔链后,形成周期性的截止频率为0的等离子体TG模式。当填充的等离子体密度较大,且腔模和TG模式发生部分重叠时,两者相互耦合,形成等离子体 腔混合模式。工作在混合模式下,其“冷带宽”和“热带宽”大大增宽,且耦合阻抗比真空时提高了近5倍,因此在填充等离子体后,耦合腔链的慢波特性得到了显著的改善。 相似文献
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A. I. Matveev 《Technical Physics》2012,57(12):1646-1655
The formation of a transverse wave with a phase velocity lower than the velocity of light, which can exist in an equilibrium plasma without a slow-wave structure in zero magnetic field, is described. It involves the transformation of a transverse wave with trapped electrons, traveling along the magnetic field, into a slow transverse wave after the removal of the magnetic field. During the evolution of the wave with trapped electrons, the magnetic induction decreases very slowly in the direction of the wave propagation. As a result, the velocity at which electrons are in resonant interaction with the wave increases; therefore, the electrons fall to the bottom of potential wells. Under the influence of the trapped electrons, the phase velocity of the wave decreases and becomes lower than the velocity of light. It becomes equal to the velocity at which the electrons are in resonance interaction with the wave at the instant when the magnetic field vanishes. It is demonstrated that a transverse wave with a velocity lower than the velocity of light can exist in an equilibrium plasma even after the magnetic field vanishes; in this case, the flow of trapped electrons serves as a slow-wave structure. 相似文献
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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. 相似文献
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A helix type slow wave structure filled with plasma is immersed in a strong
longitudinal magnetic field. Taking into account the effect of the plasma and the
dielectric, the system is separated radially into three regions. By means of
the sheath model and Maxwell equation, the distribution of the electromagnetic
field is established. Using the boundary conditions of each region, the dispersion
relation of the slow wave structure is derived. The trend of change for the radial
profile of the axial electric field is analysed respectively in different plasma
densities, plasma column radius and dielectric constant by numerical computation.
Some useful results are obtained on the basis of the discussion. 相似文献
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随着真空电子学器件的工作频率达到太赫兹波段, 表面波振荡器的横截面尺寸变小, 慢波结构的加工精度难以得到保证, 同时由于表面波振荡器的电磁场集中在慢波结构表面, 在高电压工作情况下, 太赫兹波段的表面波振荡器慢波结构爆炸发射电子会影响器件的工作特性. 本文分析了高电压工作情况下0.14 THz表面波振荡器慢波结构中电场的分布特性, 研究表明, 在慢波结构区域沿着轴线方向上存在电场幅度的包络分布, 在慢波结构中心位置处靠近慢波结构内半径处电场的幅度最大, 最易爆炸发射产生电子, 采用粒子模拟软件UNIPIC模拟了慢波结构处爆炸发射的电子对器件工作特性的影响, 同时考虑了电子回流所产生的二次电子倍增效应, 数值模拟结果表明, 慢波结构电子产生会导致器件的输出功率下降, 从数十兆瓦下降到兆瓦量级. 相似文献
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A. Ya. Kirichenko A. P. Motornenko A. F. Rusanov O. A. Suvorova V. M. Yakovenko 《Technical Physics》2001,46(4):386-390
A coaxial microwave plasmatron operating at a frequency of 10 GHz is investigated. The microwave field distribution in the plasma jet of the plasmatron is studied using a vibrating string as a small perturbation source. The phase structure of the microwave field inside the plasma is found to differ from that on the outer side of the plasma jet boundary. A slow surface electromagnetic wave propagating along the plasma jet is observed. 相似文献
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Kapchinskii M. I. Korenev I. L. Yudin L. A. Vinogradov S. V. 《Radiophysics and Quantum Electronics》1991,34(8):723-729
The effect of plasma loading in the field structure and dispersive characteristics of slow cyclotron waves propagated in electron beams is studied. A requirement is established for the maximum permissible plasma concentration at which a slow cyclotron wave can be used for collective ion acceleration. The degree of vacuum required for operation of an autoresonant accelerator is estimated.Moscow Radio-Engineering Institute, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 8, pp. 897–907, August, 1991. 相似文献
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Analysis and Calculations on Dispersion Relation and Coupling Resistance of Periodic Plasma-Cavities
The plasma tensor dielectric permittivity and electromagnetic field accurate expressions in the external axial magnetic field
are obtained from the Maxwell’s equations and the double component plasma particle linear movement equations. Further, the
flux of energy inside the plasma-cavity drift channel is presented. Based on them, some of the property of cavity passband
dispersion and coupling resistance of plasma-filled coupled-cavities slow wave structure in different plasma density and magnetic
field conditions is analyzed according to the numerical calculation. 相似文献
20.
We present an analytical study of wave spectra of
electro-kinetic waves propagating through semiconductor plasma, whose main
constituents are drifting electrons, holes and non-drifting negatively
charged colloids. By employing the hydrodynamical model of multi-component
plasma, a compact dispersion relation for the same is derived. This
dispersion relation is used to study slow electro-kinetic wave phenomena
and resultant instability numerically. We find some important modifications
in the wave spectra of the slow electro-kinetic branch. It is found that the
drift velocities of electrons and holes are responsible for converting two
aperiodic modes into periodic ones. The applied dc electric field increases
the phase velocities of contra-propagating modes. The amplification
coefficients of propagating modes can be optimized by tuning the amplitude
of applied electric field and wave number. It is hoped that the results of
this investigation should be useful in understanding the wave spectra of
slow electro-kinetic waves in ion-implanted semiconductor plasma subjected
to a dc electric field along the direction of wave propagation. 相似文献