共查询到18条相似文献,搜索用时 93 毫秒
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本文提出一种基于受激渡越辐射的的光学速调管新方案。应用著名的Madey定理对这种新型的自由电子激光器进行了分析和计算,其中包括自发辐射的和受激辐射的分析讨论。结果表明,Madey定理确能简化复杂的计算,并给出清楚的物理概念;同时计算还表明,受激渡越辐射光学速调管具有大的输出增益。文中对N个介质区构成的多级光学速调管情形也进行了讨论。
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本文从单粒子理论出发,导出了切化科夫自由电子激光中自发辐射与受激辐射的关系。结果表明:在切化科夫自由电子激光中也存在着类似于wiggler自由电子激光中的Madey公式的关系。文中还利用得出的结果对倾斜角度受激切伦科夫辐射的增益进行了计算。
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利用相干渡越辐射(CTR)测量短和超短电子束团长度是国际上束测领域新发展的频域测量技术.文中理论分析和数值计算了北京自由电子激光装置的皮秒级的射频电子束团序列产生的CTR,当辐射波长在长于束长(4ps)时,渡越辐射发生相干增强效应;与非相干渡越辐射相比,当λ≥2πσz时,增强的倍数约等于束团中粒子的数目(108);CTR从亚毫米波到毫米波段呈宽带连续谱特性;渡越辐射能量主要集中在轴线附近,宏脉冲辐射能量高达几毫焦.设计采用偏振型束团长度测量系统,利用CTR自相关技术,实验测量该束团序列的纵向长度,并藉助傅里叶变换光谱法,推求束团电子分布. 相似文献
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报道了在20TWfs激光器上采用电子磁谱仪和光学CCD积分成像相机分别对激光固体靶相互作用在靶背方向产生的超热电子能谱及其光学渡越辐射进行的测量。能谱测量结果显示:超热电子能谱呈双温类麦克斯韦分布,拟合的温度分别为90和280keV,平均温度为185keV,这与已知的温度定标率较好地吻合。光学渡越辐射测量结果显示:光学渡越辐射是由于超热电子输运穿越固体靶所致,而辐射区域呈圆盘状、有发散角、有光强分布。如果考虑超热电子的产生和加热机制,则占主导地位的加热机制是共振吸收对电子的加热。 相似文献
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为了探索超热电子束的传输特性,利用光学CCD相机在靶背法线方向测量了光学渡越辐射积分成像图案。实验在100 TW掺钛蓝宝石激光器上进行,飞秒激光与固体靶作用后,靶表面发光信号由空间分辨装置聚焦成像并引到CCD狭缝上。在厚度为20 μm的Ta靶背表面观测到渡越辐射光斑呈现较平滑的圆形结构,而且中心亮度高于周围,这包含了非相干与相干渡越辐射的成分,与理论模拟结果接近;在厚度为100 μm的Ta靶背表面观测到渡越辐射光斑呈现出星状结构,光斑较小,与高能质子发射出现的星状结构极其相似;在复合靶背表面观测到渡越辐射光斑虽然也呈现大致的圆形结构,但光斑较大,而且极不均匀,中间有很明显的光斑分裂。 相似文献
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D.A.G. Deacon K.E. Robinson J.M.J. Madey C. Bazin M. Billardon P. Elleaume Y. Farge J.M. Ortega Y. Petroff M.F. Velghe 《Optics Communications》1982,40(5):373-378
We discuss the gain measurements made on the Orsay storage ring free electron laser, and show that the peak measured gain is identical to that predicted by a modified theory which takes into account the electron trajectory distortions. This is the first free electron laser experiment in which the quality of the data is sufficiently good to permit a detailed verification of the Madey theorem. 相似文献
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J.M. Green 《Optics & Laser Technology》1981,13(5):245-251
Free electron lasers represent a radical alternative to conventional lasers, being potentially the most flexible, high power and efficient generators of coherent radiation from the ultra-violet to the far infra-red. In this review the properties of free electron lasers are discussed from both a theoretical and an experimental viewpoint, and some likely areas of application for these devices are outlined. 相似文献
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Harmonic lasing of low-gain free electron laser oscillators has been experimentally demonstrated in the terahertz and infrared regions. Recently, the low-gain oscillator has been reconsidered as a promising candidate for hard x-ray free electron lasers, through the use of high reflectivity, high-resolution x-ray crystals. In this Letter, it is proposed to utilize a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting, to enable harmonic lasing of the x-ray free electron laser oscillator, and hence allow the generation of hard x-ray radiation at a reduced electron beam energy. Results show that fully coherent free electron laser radiation with megawatt peak power, in the spectral region of 10-25 keV, can be generated with a 3.5 GeV electron beam. 相似文献
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Xiang D Colby E Dunning M Gilevich S Hast C Jobe K McCormick D Nelson J Raubenheimer TO Soong K Stupakov G Szalata Z Walz D Weathersby S Woodley M 《Physical review letters》2012,108(2):024802
Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science. 相似文献
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In this paper, the mechanism of free electron laser with a guide magnetic field is investigated by analyzing spontaneous radiation spectrum of electrons. The physical relation between spontaneous radiation and stimulated radiation in FEL with a guide magnetic field is studied. It is found that this relation in FEL is similar to that in quantum lasers. The spontaneous radiation spectrum is discrete. The frequency of stimulated radiation in FEL is oneselected and amplified in the radiation spectrum. 相似文献
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Avraham Gover 《Optics Communications》1983,45(4):281-284
Stimulated Compton-Raman scattering and free electron lasers are formulated as parametric (four-photon) or three-wave interaction processes. Manley-Rowe relations and depletable pump equations are derived for both free electron lasers and optical klystron schemes. A process of backward wave oscillation is predicted when a pump radiation field is back scattered off a codirectionally propagating e beam with frequency down conversion. A practicable experiment in the optical regime is proposed to demonstrate this effect. 相似文献
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B. Ziaja A. R.B. de Castro E. Weckert T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):465-480
We apply Boltzmann equations for modelling the radiation damage in samples
irradiated by photons from free electron lasers (FELs). We test this method
in a study case of a spherically symmetric xenon cluster irradiated with
VUV FEL photons. Qualitative agreement between the model predictions and experimental data is found. The results obtained
demonstrate the potential of the Boltzmann method for describing the complex and non-equilibrium dynamics of samples exposed
to FEL radiation. 相似文献
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A coherent x-ray generation scheme is proposed which involves characteristics of free electron lasers and atomic high harmonic generation schemes. A thin solid layer or any other periodic atomic structure with limited dimensions is exposed to a short, superintense laser pulse. The electrons are extracted from the layer due to the extreme force and penetrate periodically through the ionic structure. Consequently, thousands of harmonics of the laser radiation field are shown to coherently amplify along the interaction length. The small signal gain of the generated x-ray radiation exceeds that arising from the multiphoton Compton process in plasmas and is competitive with that in the leading x-ray free electron lasers. 相似文献