共查询到20条相似文献,搜索用时 31 毫秒
1.
Propagation of electromagnetic waves in an elliptic waveguide filled with plasma is investigated in elliptic co-ordinates. Dispersion relations for the natural modes of oscillation are obtained. Expressions for power transmitted along the waveguide are obtained as integrals of Mathieu functions. Dispersion relations for circular waveguides are also obtained as limiting cases.One of the authors (S. K. Ghosh) wishes to express his thanks to the University of North Bengal for financial support. 相似文献
2.
《Waves in Random and Complex Media》2013,23(2):259-267
A perfectly conducting elliptical cylinder filled with a warm plasma and immersed in an infinite axial magnetic field is considered. Using Maxwell’s equations and dielectric tensor, a Mathieu differential equation for axial component of electric field is obtained. Considering the boundary conditions, dispersion relation for waves in a plasma of warm electrons and immobile ions, which fills an elliptical waveguide and it is under the action of infinite axial magnetic field are calculated. Furthermore, dispersion relation and scalar potential in the quasi-static approximation in a cold magnetized plasma elliptical waveguide is calculated. The obtained results are graphically presented. 相似文献
3.
Computing Eigen value equation and modal dispersion characteristics of an elliptical Bragg waveguide
Using the method of separation of variables in the elliptical coordinate system, a recursive formula for the electromagnetic fields in a new type of Bragg waveguide having elliptical core cross section with multilayered cladding is derived. The eigen equation is written in the form of Mathieu and the modified Mathieu functions and a dispersion relation is obtained for various modes supported by the proposed Bragg waveguide. The cutoff frequencies for several lower order even-odd modes have been calculated and their propagation characteristics are plotted. The results show that the dispersion curves are discontinuous and modes can exist only in particular wavelength bands. The effects of elliptical eccentricity on the mode cutoff values and mode transmission are addressed. Finally, the modal birefringence in the said waveguide is also estimated. 相似文献
4.
首次对无衍射Mathieu光束的自重建特性进行理论和实验研究, 利用Mathieu-Hankel波理论分析了Mathieu光束的自重建机理. 基于菲涅尔衍射积分理论, 推导出了高斯吸收型圆形障碍物部分遮挡后的Mathieu光场重建后的解析表达式, 并数值模拟了无衍射Mathieu光束的经圆形障碍物部分遮挡后光场的自重建过程. 采用柱透镜-轴棱锥组合光学系统产生近似零阶无衍射Mathieu光束, 实验分别验证了轴上和轴外障碍物遮挡时近似零阶无衍射Mathieu光束的自重建特性. 理论模拟与实验结果相符. 相似文献
5.
Analysis of coaxial waveguide partially filled with chiral media 总被引:4,自引:0,他引:4
Xinzhang Wu Frédéric Mariotte 《International Journal of Infrared and Millimeter Waves》1997,18(12):2411-2435
In this paper, the canonical problem of coaxial waveguide partially filled with chiral media is analyzed by a new equivalent
transmission line network method. Both radial transmission lines in the cross section and multi-mode transmission lines in
the longitudinal direction are introduced. The symmetrical properties of the structure are also discussed. Therefore, this
method brings a clear physical picture into the wave propagation phenomena. Based on the analysis, the notable features and
the role of the chirality parameter of the medium on the reflected and transmitted guided waves are discussed. 相似文献
6.
The problem of beam dynamics in a periodically corrugated plane waveguide filled partially with nonmagnetized plasma is considered.
Short-period beam trajectories of purely waveguide type and plasma-waveguide types are found. The distribution function of
beam reflection points from the waveguide surface in the case of chaotic trajectories is calculated.
Radiophysical Nuclear Research Center, All-Russia Institute of Electronic Physics, Sarov, Nizhny Novgorod region, Russia Translated
from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 4, pp. 479–490, April, 1997. 相似文献
7.
N. S. Ginzburg I. V. Zotova A. S. Sergeev R. M. Rozental’ V. G. Shpak M. I. Yalandin A. D. R. Felps A. V. Cross 《Technical Physics》2002,47(3):335-342
Experimentally observed Cherenkov superradiance produced by a subnanosecond electron bunch traveling through a partially filled waveguide is reported. 400-ps microwave pulses with a peak power of 2 MW are obtained. The experimental results are in good agreement with the theoretical analysis and numerical simulations performed with the help of the PIC code KARAT. 相似文献
8.
P. Greiner L. Polignone C. R. Becker R. Geick 《Applied Physics A: Materials Science & Processing》1992,55(3):279-288
We report the contactless determination of the conductivity, the mobility and the carrier concentration of II–VI semiconductors by means of the technique of the partially filled waveguide at a microwave frequency of 9 GHz. The samples are CdHgTe epitaxial layers, grown on CdZnTe substrates by molecular beam epitaxy. The conductivity is determined from the transmission coefficient of the sample in the partially filled waveguide. For the analysis of the experimental data, the complex transmission coefficient is calculated by a rigorous multi-mode matching procedure. By varying the conductivity of the sample, we obtain an optimum fit of the calculated data to the experimental results. Comparison with conductivity data determined by the van der Pauw method shows that our method allows to measure the conductivity with good accuracy. The behaviour of the transmission coefficient of the sample is discussed in dependence on the layer conductivity, the layer thickness and the dielectric constant of the substrate. The calculations require to consider in detail the distribution of the electromagnetic fields in the sample region. The usual assumption of a hardly disturbed TE10 mode cannot be used in our case. By applying a magnetic field in extraordinary Voigt configuration, galvanomagnetic measurements have been carried out which yield the mobility and thus the carrier concentration. These results are also in good agreement with van der Pauw transport measurements. 相似文献
9.
The reflection characteristics of the planar surface wave antennas with different tapering profiles are analyzed by a method which transforms the radiation problem into the transmission problem of the eigen mode in the partially dielectric filled planar waveguide to avoid the difficulty of the field source problem which is met in the traditional analysis. As a result, the analysis procedure is tremendously simplified. The effect of the tapering profile on the reflection property is carefully investigated and extensive numerical results are given to establish useful guidelines for the design of the planar surface wave antennas. 相似文献
10.
The dispersion of nonsymmetrical electromagnetic waves in waveguide, partially filled with plasma, is studied numerically and experimentally. An external d.c. coaxial magnetic field is applied to the waveguide. The dispersion equation of these waves is obtained, and it is solved numerically for the experimental conditions. Results are obtained, which show coupling of the waveguide HEl1-modes with the family of the high-frequency plasma HEln-modes. The numerical dispersion curves are experimentally examined, and the influence of the magnetic field and the plasma density is studied. 相似文献
11.
Aghamir F. M. Goodarzi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2010,38(1):10-18
12.
“Cold” dispersion relation of corrugated waveguide filled with plasma immersed in a finite magnetic field 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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. 相似文献
13.
Cerenkov radiation fields excited in a partially filled circular waveguide with a channel in which an electron beam propagates are studied. The surface of the channel is covered by a thin quasi-conducting layer to remove the electrostatic charge due to the beam passage. The effect of the thickness of the cylindrical dielectric layer is investigated. The thin quasi-conducting layer is shown to attenuate the Cerenkov waves generated in the lossless medium only slightly. 相似文献
14.
N. I. Karbushev 《Radiophysics and Quantum Electronics》1991,34(7):672-679
It is shown when the cross-section of a waveguide is partially filled by magnetized plasma, slow and fast E-waves can exist simultaneously at the same frequency, which is lower than the plasma frequency. In the case of spatially periodic corrugation of the waveguide wall, the waves can be coupled, forming new waves with hybrid properties in a certain frequency range. The interaction of an electron beam with the hybrid waves differs from the interaction with a slow plasma wave in a waveguide with smooth walls or with the wave in an evacuated corrugated waveguide. For example, when two waves traveling in the same direction are coupled, the increments of the hybrid waves have values on the order of but somewhat smaller than those of the increment of a slow plasma wave in a smooth waveguide.Moscow Radio-Engineering Institute, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 7, pp. 825–836, July, 1991. 相似文献
15.
The dispersion relation for the transverse magnetic modes (TMon,) of a partially filled, dielectric-lined, cylindrical waveguide driven by a cold relativistic electron beam is derived. The effect of a gap between the electron beam and the dielectric liner is included. The dispersion relation is then used to calculate the growth rate for the Cerenkov instability in the collective tenuous beam limit. Expressions are developed for the minimum current necessary for oscillation threshold and for the power output of the Cerenkov maser in the collective regime. 相似文献
16.
采用在圆柱坐标系中分离变量的方法,推出填充多层互易手征介质的金属同轴线各层电磁场之间的关系,得到其模式特征方程和圆波导模式特征方程,给出了填充两层手征介质金属同轴线部分模式的色散特性的数值计算结果,分析了手征介质参量及两层手征介质厚度变化等对手征同轴线传播特性的影响。如果互易手征介质的手征参数等于零,可得填充普通介质的同轴线的模式特征方程。与填充普通介质的同轴线中的模式相比,手征同轴线中的模式发生了分叉。当同轴线中所填介质的折射率增大时,其模式归一化截止频率和进行基模单模传输的带宽归一化频率都将减小。 相似文献
17.
18.
Lu Zhang Ya-Xian Fan Huan Liu Xu Han Wen-Qiang Lu Zhi-Yong Tao 《Physics letters. A》2018,382(14):1000-1005
A magnetically tunable, non-Bragg defect mode (NBDM) was created in the terahertz frequency range by inserting a defect in the middle of a periodically corrugated waveguide filled with liquid crystals (LCs). In the periodic waveguide, non-Bragg gaps beyond the Bragg ones, which appear in the transmission spectra, are created by different transverse mode resonances. The transmission spectra of the waveguide containing a defect showed that a defect mode was present inside the non-Bragg gap. The NBDM has quite different features compared to the Bragg defect mode, which includes more complex, high-order guided wave modes. In our study, we filled the corrugated waveguide with LCs to realize the tunability of the NBDM. The simulated results showed that the NBDM in a corrugated waveguide filled with LCs can be used in filters, sensors, switches, and other terahertz integrated devices. 相似文献
19.
A. S. Shlapakovskii 《Technical Physics》1997,42(5):516-521
A coaxial waveguide partially filled with a dielectric as the slow-wave structure of a dielectric Cherenkov maser is investigated.
The dispersion of the fundamental mode of this waveguide is very weak at phase velocities close to the velocity of light,
and for this reason a very wide gain bandwidth is possible under conditions of an interaction with a relativistic electron
beam. The dispersion equation for an infinitely thin tubular beam in a coaxial waveguide with a dielectric liner adjoining
either the outer or inner conducting surface is derived. The gain bandwidth as a function of the parameters of the electron
beam and the slow-wave system are investigated on the basis of numerical solution of the dispersion equation, and a comparison
with similar dependences for the conventional configuration of a dielectric Cherenkov maser is made. The structural features
of the coaxial configuration which enable novel approaches to the problems of matching the microwave signal at the entrance
and exit of the system are discussed.
Zh. Tekh. Fiz. 67, 66–72 (May 1997) 相似文献
20.
《Waves in Random and Complex Media》2013,23(3):272-283
In collisional and ponderomotive predominant regimes, the propagation of microwave in rectangular waveguide filled with collisional plasma is investigated numerically. The dominant mode is excited through an evacuated waveguide and then enters a similar and co-axis waveguide filled with plasma. In collisional predominant regime, the amplitude of electric field is oscillated along propagation path; outset of propagation path due to the electron-ion collision, the intensity oscillations are reduced. Afterward, under competition between the collisional nonlinearity and absorption, the intensity is increased, so the electron density peak is created in middle of waveguide. In ponderomotive predominant regime, the intensity is slowly decreased due to collision, so the electron density is ramped. Control parameters, like the frequency, input power, collision frequency, and background electron density are surveyed that can be used to control propagation characteristics of microwave. This method can be used to control heating of fusion plasma and accelerate charged particle. 相似文献