A Second-Order Theory for Electron Plasma Solitary Waves in a Cylindrical Waveguide

To describe the long time asymptotic behaviour of weakly nonlinear plasma waves propagating in a strongly magnetized plasmafilled cylindrical waveguide the usual KDV equation which is first order in wave amplitude is extended to second order including the effects of finite temperature, mobile ions and giving a proper treatment to the radial co-ordinate for all possible modes of propagation. The second-order effects on the first-order solitary wave profile, phase speed and first order correction to the wavelength are all determined and discussed.     

The Investigation of Thermal Plasma-Loaded Free-Electron Laser: Linear Analysis

The dispersion equation of thermal plasma-loaded FEL is derived employing linear fluid theory. The characteristic of this thermal plasma FEL is analyzed in detail. FEL growth rate varying with plasma density and plasma temperature is investigated. We find there is an optimum plasma temperature where FEL growth rate can be enhanced considerably. The FEL growth rate is decreased accompanying plasma density raising.     

Investigation of Far Infrared Waveguide Free Electron Laser Driven by RF Linac

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射频远红外波导自由电子激光器的新特性

提出了用波导本征模展开的方法计算射频调制的短脉冲电子束在矩形波导中的自发辐射。模展开系数决定了辐射进入TE0n模的功率。将短脉冲理想化为时间上的d函数,可以发现当辐射频率正好等于用来调制电子束的射频的整数倍时,辐射模式表现为“纯”的波导本征模,此时辐射功率最强。用此方法估算了设计中的上海远红外波导自由电子激光器的辐射功率。     

射频远红外波导自由电子激光器的新特性

 提出了用波导本征模展开的方法计算射频调制的短脉冲电子束在矩形波导中的自发辐射。模展开系数决定了辐射进入TE_0n模的功率。将短脉冲理想化为时间上的d函数,可以发现当辐射频率正好等于用来调制电子束的射频的整数倍时,辐射模式表现为“纯”的波导本征模,此时辐射功率最强。用此方法估算了设计中的上海远红外波导自由电子激光器的辐射功率。     

拉曼自由电子激光器

文章介绍了拉曼自由电子激光器的应用，概述了我们在拉曼自由电子激光器调谐、新型小周期波荡器、具有分布反馈谐振腔的拉曼自由电子激光振荡器和虚火花放电等方面的研究进展。     

超强自由电子激光器

德国汉堡ＤＥＳＹ (ＤｅｕｔｓｃｈｅｓＥｌｅｋｔｒｏｎｅｎ -Ｓｙｃｈｒｏ ｔｒｏｎ)研究中心的科学家们获得了一种比任何其他激光都要强得多的紫外激光 .该结果证实了“自由电子激光可以将光放大数千万倍”的预言 .由于这种紫外光所具有的特殊性质 ,它是目前一种最强大的研究工具 ,这也意味着朝超强Ｘ射线激光迈出了重要的一步 .超强Ｘ射线激光在物理、化学、生物和医学中都有着广泛的应用前景 ,这对于材料微区结构、微区化学组分与微区物性间的关系的研究 ,也是一大福音 .传统的激光是由电子在原子或分子中确定的能级间跃迁产生光发射实…     

Linear Theory of Electron Dynamic for the Slowly Varied Section Waveguide Resonator with the TM Mode in a Hybrid-Magnicon

Based on fundamental principles of magnicon, we posed hybrid-magnicon amplifier. It are adopted that beforehand axially modulating annular electron beam, a vertical cylindrical wave-guide opened driver cavity, a slowly varied section waveguide opened output cavity, whoever with TM-mode. Pass basic concept analysis of this new type tube that after consider who suitably make small power or MW pulsed tube with suitable wide-band. For example, if operate at the third harmonic then can reach 8% bandwidth. This paper expounded the linear theory for hybrid-magnicon. Use simply new method, which solve for Dispersion Equation. Give Dispersion Equation with the self-consistent effect and the space charge effect of the slowly varied section waveguide rotating TM-mode opened resonator cavity. Give the interact power between wave and electrons, et al.     

Study of Polarizer Characteristics with a High-Power Terahertz Free Electron Laser

Though wire grid and strip polarizers are widely used for control of submillimeter radiation, both calculated and experimentally measured values of their transmission are often contradict one another. We have measured the transmission of wire and thin-film photolithographic polarizers at a wavelength of 0.13-mm using 100 W free electron laser radiation and compared the results with previous experiments and calculations. Using a thin-film photolithographic polarizer we showed that radiation of the Novosibirsk FEL after traveling through a 14-m beamline is plane-polarized with the degree of polarization better than 99.6%.     

Linear Cold-Fluid Theory of a Free-Electron Laser

The linear cold-fluid theory of a free-electron laser is given where the laser field must be in the two-mode operation. The ration between the two modes of laser field is obtained. The dispersion relation is discussed in the Raman- and Compton-regimes and the space-charge wave theory is worked out.     

喇曼自由电子激光振荡器

本文报道喇曼自由电子激光振荡器的研究结果。脉冲加速器电子束能量０．４ＭｅＶ，束流８００Ａ。采用满足布喇格条件的分布反馈谐振腔，取代传统的激光器反射镜。理论上进行了分析和设计，采用正弦形波结构选择振荡模式。喇曼自由电子激光振荡器实验表明，输出光谱显著变窄。频率分布半高宽度，超辐射下范围为７．５ｍｍ～９．２ｍｍ，分布腔下范围为８．６ｍｍ～８．９ｍｍ。     

矩形波导中超短脉冲电子束的相干同步辐射

考虑了当射频调制的超短脉冲电子束径向长度远小于辐射波长时，将其理想化为δ时间函数，提出了用波导本往模展开的方法来计算矩形波导中超短脉冲电子束的相干同步辐射及其频率特性。结果表明：（１）当谐振频率等于调制电子束微脉冲时间隔的射频的整数倍时，辐射模式表现为“纯”的波导本征模。（２）波导效应使得超短脉冲电子束在两个频率处发生相干同步辐射，而且低频支的辐射功率高于高频支的。最后指出波导自由电子激光器单横模     

Relativistic Cloud-In-Cell Simulation of Free Electron Laser

We have developed one-and a half-dimensional (one space dimension and two velocity components) relativistic electromagnetic cloud-in-cell simulation (CIC-R) code which is suitable for simulating the free-electron laser process. Using CIC-R we have simulated the temporal evolution of the free-electron laser, and obtained the results on the linear growth rates of the unstable spectrum and the dispersion relation of the coupling between the electromagnetic waves and electrostatic waves which agree with the theory. Other results such as the time development of the electron distribution function, nonlinear saturation and the efficiency of energy conversion are also presented in detail.     

不用导引磁场的虚火花束源拉曼自由电子激光器的数值计算

采用非线笥模型对拉曼自由电子激光器进行数值模拟,发现虚火花束源自由电子激光器苛以去掉导引磁场,用小周期摇摆器,实现器件的小型化和高功率。     

Linear Theory of Plasma-Filled Coaxial Cylindrical Cherenkov Maser

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.     

求解自由电子激光场的微扰方法

借助于固体理论中的ＬＬＰ变换研究自由电子激光场的光子统计性质，并发展了一种微扰方法予以求解。     

Ultrafast Dynamics Using Free Electron Laser Sources

As avid readers of SRN know, free electron lasers have recently emerged as important synchrotron-radiation-based tools for a broad range of scientific studies. The combination of their short wavelength (from VUV to hard X-ray) with their exceedingly brief pulses (down to a few femtoseconds), high pulse energy, and coherence makes them particularly useful tools for studying ultrafast dynamics with chemical specificity and atomic-scale structural sensitivity.     

Proposal for Efficiency Enhancement of a Far Infrared Free Electron Laser

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Small-signal gain of Free Electron Laser in a resonator Gaussian mode

We present an analytical expression for the small-signal gain of a Free Electron Laser (FEL) in the presence of a Gaussian mode. To describe the electron beam evolution we use the one-dimensional (1-d) Vlasov equation. Our perturbation result, valid for small values of the parameterq (length of the undulatorL divided by the Rayleigh rangeZ _R), can be extrapolated to values ofq4÷5.