共查询到17条相似文献,搜索用时 61 毫秒
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对入射等离子体的相对论电子注(REB)在离子通道中可能产生切连科夫(Cherenkov)辐射的问题进行了论证与研究.利用线性理论分析了离子背景下的注-波互作用关系,导出了系统的色散方程与同步辐射条件.结果表明,系统的电磁不稳定性是由离子通道中TM模与电子注模通过电子注耦合所致,其微观机理是离子对电子注的聚焦.对处于运动等离子体状态下的离子-注系统进行了严格地理论分析,获得了通道内辐射波的频偏与波增长率公式,并通过数值模拟计算讨论了系统有关参数对它们的影响.
关键词:
离子通道
等离子体
切连科夫辐射 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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讨论了γ光子在同一种介质中连续产生康普顿散射和切连科夫辐射的条件。这一条件可用产生切连科夫辐射的康普顿电子在介质中的临界散射角的大小来表示。 相似文献
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采用等离子体流体理论,从线性扰动方程出发,研究了电子束电流大小对介质切伦科夫脉塞中束波相互作用色散关系的影响,得到了当等离子体返回电流能有效中和与不能有效中和电子束电流两种情形下色散关系和波的增长率,并讨论了电子束电流对束波相互作用色散关系和波增长率的影响。研究表明,等离子体返回电流能有效中和与不能有效中和电子束电流两种情况下有着不同的色散关系和波的增长率。在波导参数和背景等离子体参数固定的情况下,电子束电流并不是越大越好,电子束电流过大不利于提高器件效率,它们之间存在最佳匹配关系。 相似文献
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托卡马克理想磁流体不稳定性的统一描述 (I) 总被引:1,自引:0,他引:1
石秉仁 《核聚变与等离子体物理》2001,21(2):65-72
在与平衡磁面相联系的坐标系下,用剪切阿尔芬波近似给出了统一描述托卡马克等离子体理想磁流体线性运动的本征模方程。利用此方程,可以进一步给出大尺度扰动(扭曲模、低模数气球模、阿尔芬模)和小尺度扰动(高模数气球模、Mercier模)的本征模方程。本文详细讨论了小尺度扰动的本征模方程。 相似文献
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Jianqiang Wu Caidong Xiong Shenggang Liu 《International Journal of Infrared and Millimeter Waves》1995,16(8):1317-1328
The effect of three-dimensional perturbed velocity and three-dimensional perturbed current density on the beam-wave interaction of dielectric Cherenkov maser is analysed by use of the self-consistent linear field theory. Three distinct cases are considered. First, the propagation of the electron beam in an annular dielectric liner enclosed by a loss-free conducting wall is investigated. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. It's clearly shown that the instability of the interaction results from the coupling of the TM mode in the dielectric lined slow-wave waveguide to the beam mode via the electron beam. And the coupling is proportional to the density of the beam. The growth rate of the wave produced by the electron beam are obtained. Then, the case of a relativistic electron beam guided by a longitudinal magnetic field in the same slow-wave structure is examined. The motion of electrons could be approximated to be one-dimensional when the simultaneous condition of the beam-wave interaction of dielectric Cherenkov maser is satisfied. Finally, the effect of the background plasma on the instability of the beam-wave interaction is studied.This work is supported by National Natural Science Foundation of China. 相似文献
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Jianqiang Wu Shenggang Liu Yuanlong Mo 《International Journal of Infrared and Millimeter Waves》1995,16(12):2181-2194
On the basis of the reference [1], excitation of Cherenkov radiation with arbitrary azimuthal mode number by a thin annular relativistic electron beam in a plasma-filled dielectric-lined slow-wave waveguide is studied in this paper. A determinantal dispersion equation is obtained. This general dispersion equation is valid for arbitrary azimuthal mode number, and the growth rate of the wave is derived from it. Finally, the effects of the background plasma density on the dispersion relation, the background plasma density and the electron beam radius on the growth rate of the wave are presented. Formulas and results offerd in this paper are general, and are of particular value of reference to the beam-wave interaction in azimuthally unsymmetrical slow-wave waveguide.This work is supported by National Natural Science Foundation of China and 863 Project. 相似文献
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Garate E.P. Fisher A. Main W.G. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(5):831-836
The linearized Lorentz force, continuity equation, and Maxwell's equations are used to calculate the system dispersion relation for a coaxial configuration of the dielectric Cherenkov maser. The system consists of two coaxial conductors lined with dielectric and an annular relativistic electron beam, which propagates between the two liners. The dispersion relation for the beam and dielectric-lined coaxial waveguide structure and the no-beam system that describes the dependence of the generated frequency on the coaxial waveguide parameters are presented. Using the linearized dispersion relation, the growth rate for the beam-TM0n waveguide mode instability is calculated in the strong-coupling tenuous beam limit 相似文献
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Wu Jianqiang 《International Journal of Infrared and Millimeter Waves》2003,24(12):2153-2162
Injection of background plasma into the beam-wave interaction region can greatly enhance the beam-wave interaction efficiency and the microwave output power of the device. In this paper, a new type of plasma-filled slow-wave structure, i.e., plasma-filled, dielectric-loaded coaxial cylindrical waveguide with a dielectric ring enclosing tightly the inner conductor, is developed. The Cherenkov radiation excited by the beam-wave interaction in the slow-wave structure is examined by use of the self-consistent linear field theory. The dispersion equation and the synchronized condition of the beam-wave interaction are derived. It's clearly shown that the Cherenkov radiation excited by the beam-wave interaction results from the coupling between the slow electromagnetic wave, TM-modes, propagated along the slow-wave structure and the negative-energy space-charge wave propagated along the relativistic electron beam. And the wave growth rate is solved, and the beam-wave energy exchange in the presence of the background plasma is discussed. Finally, the effects of the background plasma density on the dispersion characteristics, the distribution of the longitudinal fluctuating electric field, the wave growth rate and the beam-wave energy exchange are calculated and discussed. 相似文献
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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
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Chang S.-F.R. Scharer J.E. Booske J.H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(3):293-304
The hybrid-mode dispersion relation and resonant growth rates are solved for a finite-thickness sheet electron beam propagating through a rectangular guide with a thin dielectric slab. Analytic results for the growth rates, bandwidth and mode competition for an infinite magnetic field in the limit of a dilute beam are then presented. To properly couple to the desired EH10 hybrid amplifier slow wave mode, the coupled waveguide mode equations are solved for a dielectric taper to accomplish the TE10 to EH10 mode transition. A piecewide linear taper which suppresses the competing EH11 mode and other hybrid modes is developed and the overall amplifier system is discussed 相似文献
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Tripathi V.K. Liu C.S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(4):583-587
A simple calculation of a free-electron laser in the Compton regime that uses a dielectric-lined waveguide is presented. The introduction of a dielectric lining in a free-electron laser considerably reduces the requirements on beam voltage for generating a given frequency ω1=k 0c/(1 - vb η/c), where k 0 is the wiggler wave period η is the effective index of refraction (1<η<√ϵ) and ϵ is the permittivity. The system supports electromagnetic waves whose Poynting flux is largely concentrated in the dielectric; hence the electron beam is required to propagate close to the dielectric lining. The mode structure and dispersion behavior of the guiding system without the beam are discussed. a thin annular beam is introduced, and a perturbation theory is used to obtain the frequency and growth rate of radiation 相似文献