共查询到19条相似文献,搜索用时 390 毫秒
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分析了电磁波以任意角度入射到有限磁场中的激光等离子体通道天线(LPCA)时的电磁散射特性。根据LPCA的工作原理建立了其电磁分析模型,推导出广义柱坐标系下各向异性磁化等离子体中纵向分量所满足的波动方程和纵向场与横向场的关系,得到LPCA和周围媒质中的电磁场,利用边界切向电磁场连续,得出了散射系数方程。通过计算实例,将结果与文献结果比较,吻合较好。该研究结果预期可应用于高功率微波武器系统的研究。 相似文献
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分析了有限磁场中激光等离子体通道周围为有耗气体介质时激光引导电磁脉冲传播的一般模式的传播特性,建立了有限磁场中激光等离子体通道引导电磁脉冲的几何模型,导出了广义柱坐标系下各向异性介质中纵向场所满足的波动方程及纵向场与横向场的关系。利用边界条件给出了有限磁场中激光引导电磁脉冲传播模式的严格特征方程,重点讨论了传播常数随等离子体参数、周围介质参数和外加磁场的变化。结果表明,有限磁场中激光引导电磁脉冲的传播特性比无磁场或外加无穷大磁场时更具有可控性。 相似文献
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利用自洽线性场理论,导出了薄环形相对论电子注通过填充等离子体的介质同轴波导中的注波互作用色散方程,得到了注波互作用产生切伦科夫辐射的同步条件和波增长率。分析了填充等离子体后的波与电子注之间的能量交换及等离子体密度对色散特性、波增长率和注波能量交换的影响。分析结果表明:切伦科夫辐射是由沿介质同轴波导传播的慢波与沿薄环形相对论电子注传播的负能空间电荷波耦合所致,且其耦合强度与电子注的密度成正比;输出频率和波增长率随着填充等离子体密度的增大而提高;保持一定的输出频率,增大电子注的束流可得到高的微波输出功率。 相似文献
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研究了平面电磁波在磁化、稳定、二维、非均匀等离子体中的传播特性;采用等效输入阻抗方法计算非均匀磁化等离子体层对不同模式入射电磁波的功率吸收情况。结果表明,电子数密度、碰撞频率和外磁场大小是等离子体对电磁波功率吸收的主要影响因素。采用等效介电常数的方法模拟等离子体特性,代入有限元软件进行平面电磁波入射等离子体仿真,得到了非寻常波与右旋极化波的吸收特性。根据数值计算和全波仿真结果可知,当等离子体密度为1017 m-3、碰撞频率2.5 GHz、外加磁场的磁感应强度为0.15 T时,磁化等离子体对电磁波有强烈的吸收特性。 相似文献
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利用坐标系转换矩阵给出实验室系中磁化等离子体介质的频域极化率张量, 采用部分分式展开方法通过傅里叶逆变换得到极化率张量的时域指数函数形式, 应用数字信号处理中的半解析递归卷积算法, 给出适用于处理任意外磁场方向情形下磁化等离子体目标电磁散射的半解析递归卷积-时域有限差分计算方法. 计算了磁化等离子体球的同极化和交叉极化后向雷达散射截面, 结果表明了算法的正确有效性.
关键词:
半解析递归卷积
磁化等离子体
电磁散射
时域有限差分方法 相似文献
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Hiroshi Tsukuda Masaru Masuzaki Norio Toyosugi Cha Yeol Lee Ritoku Ando Keiichi Kamada Tsuguhiro Watanabe 《International Journal of Infrared and Millimeter Waves》2001,22(8):1147-1162
A linear analysis is described on stabilities driven by an intense relativistic electron beam in an infinitely long, plasma-filled, and dielectric-lined circular waveguide immersed in a finite strength axial magnetic field. A dispersion equation is derived from the cold fluid theory and solved numerically. Beam-plasma instabilities due to interaction between beam modes and the Trivelpiece-Gould modes appear as well as the Cherenkov and the cyclotron Cherenkov instabilities. Parametric researches are carried out varying magnetic field strength, plasma density, and dielectric constant. Effects of a finite magnetic field and plasma filling are discussed in connection with the possibilities of using this system as a microwave radiation source. 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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《Physics letters. A》2005,336(6):477-489
By numerically solving the exact dispersion equation, the dispersion relation of symmetrical TM waves propagating in a Čerenkov maser including a thin annular relativistic electron beam (TAREB), a strongly magnetized plasma column, and a dielectric rod is investigated. The effects of accelerating voltage, radii of TAREB and plasma column as well, on the frequency spectra and spatial growth-rate coefficient are presented. The axial electric field profiles during the wave amplification and the conditions under which the spatial growth rates are maximum are presented. 相似文献
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Experimental results on interaction of a rotating relativistic electron beam with plasma and neutral gas are presented. The
rotating relativistic electron beam has been propagated up to a distance of 150 cm in a plasma. The response of the plasma
to the rotating electron beam is found to be of magnetic diffusion type over a plasma density range 1011–1013 cm−3. Excitation of the axial and azimuthal return currents by the rotating beam and subsequent trapping of the azimuthal return
current layer by the magnetic mirror field are observed. A field-reversed configuration has been formed by the rotating relativistic
electron beam when injected into neutral hydrogen gas. We have observed field reversal up to three times the initial field
in an axial length of 100 cm. 相似文献
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Yaduvendra Choyal Lalit Gupta Prasad Deshpande Krishna Prasad Maheshwari Kailash Chander Mittal Suresh Chand Bapna 《Pramana》2008,71(6):1301-1310
In this paper, a high power relativistic backward wave oscillator (BWO) experiment is reported. A 230 keV, 2 kA, 150 ns relativistic
electron beam is generated using a Marx generator. The beam is then injected into a hollow rippled wall metallic cylindrical
tube that forms a slow wave structure. The beam is guided using an axial pulsed magnetic field having a peak value 1 T and
duration 1 ms. The field is generated by the discharge of a capacitor bank into a solenoidal coil. A synchronization circuit
ensures the generation of the electron beam at the instant when the axial magnetic field attains its peak value. The beam
interacts with the SWS modes and generates microwaves due to Cherenkov interaction. Estimated power of 2 MW in TM01 mode is observed.
相似文献
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In this work we investigate the effect of a relativistic homogeneous electron beam on the field stability and minimizing the energy losses in waveguide filled homogeneously with plasma. Analytical calculations are performed to find the plasma dielectric tensor by applying the boundary conditions at the plasma‐conductor interface. We derive the dispersion equations which describe the propagated E‐ and H‐waves and their damping rate. The necessary condition for the field stability in the waveguide and the amplification coefficient for the E‐wave are obtained. The effects of plasma warmness and an external static magnetic field are taken into consideration. Relativistic electron beam is found to play a crucial role in controlling the field attenuation in waveguide. 相似文献
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Excitation of microwave by an annular electron beam in a plasma-filled dielectric lined waveguide 总被引:1,自引:0,他引:1
Jianqiang Wu Caidong Xiong Shenggang Liu 《International Journal of Infrared and Millimeter Waves》1995,16(9):1573-1581
An axial relativistic electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. This phenomenon of Cherenkov emission is the basis of all traveling wave tubes. In this paper an excitation of Cherenkov radiation by a thin annular relativistic electron beam in a plasma-filled dielectric-lined waveguide is analysed by use of the self-consistent linear theory. The effect of the thin annular electron beam on the beam-wave interaction is completely described by a jump condition. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. Finally, the growth rate of the wave is obtained, and the effect of the background plasma density and the electron beam radius on the growth rate of the wave are presented.This work is supported by National Natural Science Foundation of China. 相似文献
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《Waves in Random and Complex Media》2013,23(3):472-490
The theoretical investigation of terahertz waves and their excitation by electron beam injection in a cylindrical metallic plasma waveguide is investigated. This metallic waveguide includes a cold collisionless unmagnetized annular degenerate plasma and a dielectric rod. The dispersion characteristics of these waves, the frequency spectra of fast and slow E-modes waves (transverse magnetic field), are studied. Also, the effects of the dielectric permittivity, the radius of the dielectric rod and the radius of the plasma on the frequency spectra and the time growth rate of waves are simulated. In addition, the electric field profiles in this waveguide are plotted. 相似文献
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GuangJun Wen JiaYin Li FuZhen Xie ShengGang Liu 《International Journal of Infrared and Millimeter Waves》1999,20(1):57-69
A two and one half dimensional particle-in-cell code MAGIC has been used to investigate the nonlinear beam-wave interaction in a coaxial relativistic backward wave oscillator(RBWO) and optimize the dependence of the output power on electron beam nature parameter, slow wave structure geometry and magnetic guide field. The optimum conditions for the coaxial RBWO were obtained. The simulation results show: the coaxial RBWO can generate 3.2GW peak output power at 10.2GHz in the TM02 made when an annular electron beam of 20KA is accelerated across a diode potential of 600KV and guided through a section of uniform coaxial corrugated waveguide by an axial magnetic field of 25KG, the peak efficiency is about 27% . A novel coaxial master oscillator–power amplifier was presented in this paper. 相似文献