共查询到19条相似文献,搜索用时 93 毫秒
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本文利用自由电子激光(FEL)纵模统一理论讨论了光学速调管自由电子激光相干谐波的输出情况。从物理上分析了非对称光学速调管的设计,得出了采用非对称的光学速调管可使FEL的相干谐波输出提高近30%。 相似文献
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利用自由电子激光(FEL)纵模统一理论,系统地分析了光速调管FEL的小信号增益理论,并对色散参数Nd、束流能散度和发射度的影响进行了讨论。 相似文献
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曙光一号自由电子激光装置的设计研究 总被引:1,自引:0,他引:1
曙光一号自由电子激光装置(SG-1 FEL)是一台高功率毫米波段自由电子激光放大器,它由3.5MeV直线感应加速器、电子束调制系统、变参数摇摆器和微波种子源等部件组成。本文扼要叙述了SG-1 FEL的物理设计和主要技术参数,并重点分析了各主要部件的实验研究、计算模拟,以及物理设计和结构的特点。 相似文献
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根据于敏教授的自由电子激光纵模统一理论,推导了磁场含有随机误差影响时光场的小信号增益和指数增益。并且结合曙光一号FEL装置,给出了指数增益区磁场随机误差σ与增益参数g_0的定标关系。同时利用三维WAGFEL程序详细地模拟计算了磁场随机误差对自由电子激光增益和饱和增益的影响。线性理论的结果得到了模拟计算的证实。 相似文献
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自由电子激光辐射频谱测量 总被引:1,自引:0,他引:1
文章描述了在环形电子束和实心电子束自由电子激光(FEL)研究中,测量辐射频谱使用的两种方法——波导色散线和带通滤波器谱仪。介绍了测量系统的组成和特点,给出了测量结果:环形束FEL试验。辐射频率在27—38GHz内可调:实心束FEL试验,辐射频谱带宽~1.2GHz。 相似文献
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Axial magnetic field effect in numerical analysis of high power Cherenkov free electron laser 下载免费PDF全文
《中国物理 B》2019,(6)
Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. For three sets of parameters, in high power CFEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam's distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning. 相似文献
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In this article, we propose a quantum regime for Cherenkov free-electron laser (CFEL) and surface plasmon polaritons (SPPs) excited in dielectric and multilayer graphene waveguides, respectively. This quantum regime is realized when the momentum spread induced in the interaction is smaller than the photon recoil. The discrete momentum exchange characterizing this interaction yields a significantly narrow single emission line. To determine the condition of the quantum regime, we derive an expression for the gain in the Cherenkov effect using a quantum mechanical treatment. It is assumed that the effective spread in momentum is due to the finite interaction length L (or the propagation length in the case of SPPs). For both cases, CFEL and SPPs, the effects of electron beam and waveguide parameters on the possibility of the quantum regime are studied. We conclude that the quantum regime can be basically verified at low electron beam energy (<40 keV) and at emission wavelengths in the near infrared range (<5 μm) when L is in the order of millimeters. In the case of SPPs, we also show that the feasibility to realize quantum SPPs is enhanced by increasing the chemical potential and number of graphene layers. 相似文献
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The radiation characteristics of the double dielectric grating leaky-wave antenna are analyzed by the improved perturbation method. The results indicate that under the condition of the same radiation intensity, the double dielectric grating antenna has relatively smaller dimensions than that of the single one. It is undoubtly of great importance in the case that the limitation of the weight and volume of system is strictly required. The results obtained from this paper are compared with the exact solution based on the mode matching method. It is justified that the present perturbation procedure yields as highly results as the rigorous approach with extremely simplicity of the analysis and calculations. 相似文献
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R. A. Dynich V. A. Kovtun-Kuzhel A. N. Ponyavina 《Journal of Applied Spectroscopy》2012,78(6):817-822
Angular dependences of electromagnetic radiation scattered by separate finite dielectric cylinders and their ordered assemblies
have been numerically simulated using a volume integral equation formalism. Dependences of directional diagrams on optical-geometric
parameters of both the separate finite cylinders and their spatial ordering were studied. It is shown that collective effects
of a coherent nature in the assembly of spatially ordered cylinders result in a scattered radiation angular distribution that
differs strongly from that obtained for a system of cylinders that are not electrodynamically coupled. 相似文献
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The elements of the scattering matrix of the junction between two circular monomode dielectric waveguides with different diameters and/or different refractive indices are calculated using the mode matching method. The theory is evaluated numerically for a wide range of parameters and simplified considerably for two important cases of weakly guiding waveguides.The radiation pattern of the junction is calculated using the Huygens-Kirchhoff theory of diffraction and shown to be reducible to the weighted difference of the radiation patterns of the ends of the primary and secondary waveguide. Simple approximations are derived for weakly guided waves.The theory is verified experimentally by measuring the scattering parameters, the far-field radiation pattern and the near-field distribution of abrupt changes in diameter of microwave dielectric rod transmission lines. 相似文献
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Weihai Fang Shanjia Xu 《International Journal of Infrared and Millimeter Waves》2006,27(12):1683-1694
The effects of left-handed materials (LHM) on frequency selective reflection and transmission characteristics of dielectric
periodic structures are carefully investigated using a method which combines the multimode network theory with the rigorous
mode matching method. In addition, the effects of LHM dielectric loss on the selective properties are also given. It has been
shown that the selective behavior of periodic structures can be modified by adding LHM layers above and below the periodic
layer.
Supported by the National Natural Science Foundation of China (No. 60171037) (No. 60371010) and (No. 63531020) 相似文献
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The radiation forces on a Rayleigh dielectric sphere induced by a focused partially coherent elegant Laguerre-Gaussian (ELG) beam are investigated by using the Rayleigh scattering theory. It is found that a focused partially coherent ELG beam with suitable mode orders can be used to trap a Rayleigh particle whose refractive index is larger or smaller than that of the ambient by varying its initial spatial coherence width. Therefore, one can use one optical-trap system to trap two types of particles with different refractive indices. 相似文献
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Yanrui Wu Xiaoshuang Chen Wei Lu 《International Journal of Infrared and Millimeter Waves》2006,27(3):425-434
We have studied absorption and thermal radiation for a three dimensional lossy photonic crystal of dielectric spheres by using
a multiple scattering method. It is shown that such simple structures have excellent selective thermal radiative characteristics
in different photonic bands. There is stronger thermal radiation at high frequency than that at low frequency. In comparison
with the uniform slab without photonic crystal structure, in the photonic band gap, the thermal emission intensity is greatly
suppressed and very weak, but not zero due to the penetration depth. Under the same lattice structure, the thermal emission
of photonic crystal varies with the change of the radius of the spheres. 相似文献