圆波导契伦柯夫自由电子激光流体描述

用磁流体理论研究了契伦柯夫自由电子激光的性质,导出了空心束驱动的圆柱对称波导契伦柯夫自由电子激光的色散关系,利用色散关系计算了契伦柯夫不稳定性增长率,给出了饱和功率的估计值,考虑了束与介质间间隙对契伦柯夫自由电子激光的影响,并就空心束与实心束情况进行了比较。     

圆波导契伦柯夫自由电子激光的单粒子理论

用单粒子理论研究了契伦柯夫自由电子激光的基本性质,给出了空心束圆柱衬介质波导契伦柯夫自由电子激光调谐特性,导出了增长率表达式,计算了克服谐振腔损失所需阈值电流和相互作用效率,讨论了束与介质间间隙的影响,并对空心束与实心束进行了比较,最后讨论了电子束品质对契伦柯夫自由电子激光的影响。     

多电子束契伦柯夫自由电子激光振荡器

我们对多电子束契伦柯夫自由电子激光进行了首次实验研究。280A,500kV的电子束被引入一多介质矩形谐振腔,在频率为33.4GHz处产生了1.7MW的契伦柯夫相干受激辐射。互作用效率为1.2％。     

测量电子束流的小型法拉第筒

介绍一种测量束流强度不大于50kA,能量不超过0.8MeV的小型法拉第筒。经标定,此法拉第筒上升前沿小于6ns。已用于契伦柯夫自由电子激光的传输束流测量。     

填充等离子体的切伦柯夫自由电子激光的理论分析

本文用磁流体理论研究了柱形波导填充等离子体的切伦柯夫自由电子激光器，表明该系统比普通切伦柯夫自由电子激光具有更高的工作频率和线性增长率。发现在入射电流和波导结构一定时，该系统和普通切伦柯夫自由电子激光器的增长率并不是随随电子束与介质的间距的增加而减小，而是存在一个最佳值。     

多波契伦柯夫振荡器的实验研究

 建立了一套X波段多波契伦柯夫振荡器装置,并进行了实验研究,获得了基于多波契伦柯夫振荡器机制的微波辐射。实验测得的微波频率介于9.59~10.4GHz,辐射效率大于10%,微波功率超过100MW。     

气体探测器的最新应用

本文讨论了气体探测器在下述领域的最新应用:放射性痕量元素的二维图像;用X 射线衍射研究晶体结构;工业射线照相法;用核扩散的射线照相;契伦柯夫环探测器;流光管量热计;渡越辐射测量;用作电磁量热计的高密度显像室;用作探测契伦柯夫环的显像室。     

带Wiggler场平板型部分填充介质CFEL的切仑柯夫自由电子激光的动力学耦合模理论

用二维波动力学耦合模理论研究了带Wiggler场平板型部分填充介质的FEL。研究结果表明,该系统可用低能电子束产生对介质厚度无特殊要求的短波长FEL。适当选择参数,可使其增长率和效率高于普通自由电子激光和切仑柯夫自由电子激光,并证明本系统超辐射放大的工作主模应是纵向截面电场模。     

双介质片平面波导契伦科夫自由电子激光

给出双介质片平面波导契伦科夫自由电子激光波导模式的色散关系,求出器件的单程增益并证明存在一组新的波导模式__奇模。讨论了器件的工作频率和单程增益随介质片厚度、电子束能量和电子束通道宽度的变化关系。还研究了这组奇模对器件的影响。     

国防科大契仑柯夫自由电子激光器通过鉴定

由国防科技大学承担的国家高技术契仑柯夫自由电子激光(CFEL)研究项目于1993年3月30日至31日在长沙通过鉴定。国家高技术410主题专家组办公室主持了这次技术鉴定和验收工作。主题专家组首席科学家杜祥琬研究员任鉴定委员会主任委员。     

Plasma physics issues in gas discharge laser development

An account is given of the interplay between partially ionized plasma physics and the development of gas discharge lasers. Gas discharge excitation has provided a wide array of laser devices extending from the soft X-ray region to the far infrared. The scaling of gas discharge lasers in power and energy also covers many orders of magnitude. The particular features of three regimes are discussed: short wavelength lasers (deep UV to soft X-ray), visible and near UV lasers, and infrared molecule gas lasers. The current status (fall, 1990) of these areas is reviewed and an assessment is made of future research topics that are perceived to be important     

Collective and single-electron interactions of electron beams with electromagnetic waves,and free-electron lasers

The field of radiation emission from electron beams is reviewed with special reference to work related to free-electron lasers. Different schemes of interaction in periodic structures, electromagnetic slow-wave structures, and in transverse confining force are distinguished. Various effects and devices such as traveling wave amplifiers, Smith-Purcell radiators, Cerenkov and bremsstrahlung-free electron lasers, cyclotron resonance masers, coherent bremsstrahlung and channeling radiation are discussed and the differences and relations among them are explained. A simple comprehensive model is developed to describe electron-beam interaction with an electromagnetic wave in periodic electromagnetic structures. The model is general enough to describe both collective and single-electron modes of interaction and quantum mechanical, classical and Fermi degenerate regimes. Simplified expressions are developed for the gain by stimulated emission of radiation and for gain conditions of the Smith-Purcell-Cerenkov type free-electron lasers under conditions of very thin electron beams and infinite interaction length. This research is supported by the Air Force Office of Scientific Research under contract AFOSR-76-2933     

一种新型短波长自由电子激光

本文提出一种可以工作在软X射线区的用孤子激光抽运的新型自由电子激光器,利用孤立子激光的波型以及单粒子小信号分析方法,发现这种自由电子激光具有以下两个不同于以往电磁波振荡器自由电子激光的特点:(1)很小的“质量漂移效应”(mass-shift effect),这是由孤立子激光抽运的特征所决定;(2)具有一个附加的“频率调谐性”,即可展宽自由电子激光的频率调谐能力。对获得的小信号增益也进行了一些分析和讨论。 关键词：     

超快X射线自由电子激光研究进展北大核心CSCD

现代光源的发展不断推动着人们从更深层次上理解物质的基本结构和动力学行为。X射线自由电子激光作为最先进的光源,其超高的峰值功率、超短的脉冲长度和优良的相干性,为人们以原子级时空分辨率探测和操控物质中的超快过程提供了可能。目前全世界已有多个X射线自由电子激光装置建成并投入使用,在原子分子物理、化学、生命科学、材料科学等各学科应用中都显示出了重要价值。同时大量的研究工作也集中于继续提高X射线自由电子激光的性能,包括把脉冲持续时间从fs量级进一步缩短至as量级,这将为超快科学的发展带来新突破。以超快脉冲产生为主线,综述了近年来超快X射线自由电子激光产生方案的研究进展,从产生原理、方案特性、最新成果等方面介绍了各类产生方案,总结对比了各方案的优缺点,最后对超快X射线自由电子激光的未来发展方向进行了展望。     

Intracenter Raman silicon lasers

Raman-type Stokes stimulated emission in the far-infrared wavelength range (52–65 μm) has been realized in silicon crystals doped by group-V hydrogen-like donor centers at low temperatures under optical excitation by radiation from a pulsed frequency-tunable infrared free-electron laser. The light scattering appears as an entire intracenter process and occurs on the donor electronic transitions being resonant to the intervalley transverse acoustic g phonon. The outgoing and incoming electronic donor resonances amplify the efficiency of scattering, so that the Raman optical gain increases to the values observed for the infrared room temperature Raman silicon lasers.     

自由电子激光中空间电荷波的单电子分析

从单粒子模型理论出发,对考虑空间电荷的自由电子激光进行了分析,并提出了迭代计算方法,计算结果表明,自由电子激光中三波耦合的一次迭代解与已有结果一致,二次迭代解显示了空间电荷波有更复杂的结构. 关键词：     

Electron-beam conditioning by thomson scattering

A method is proposed for conditioning electron beams via Thomson scattering. The conditioning provides a quadratic correlation between the electron energy deviation and the betatron amplitude of the electrons, which results in enhanced gain in free-electron lasers. Quantum effects imply conditioning must occur at high laser fluence and moderate electron energy. Conditioning of x-ray free-electron lasers should be achievable with present laser technology, leading to significant size and cost reductions of these large-scale facilities.     

Optimization of a seeded free-electron laser with helical undulators

Seeded single pass free-electron lasers are promising coherent, short-duration, and intense light sources, from the visible to x rays. Operated with adjustable undulators, they are also a unique device for providing fully variable polarized radiation. We report here the first seeding of helical undulators with a variable polarized source. We demonstrate that the adjustment of the seed polarization and focusing allows the free-electron laser radiation to be optimized in terms of intensity and quality.     

Quadratic detection with two-photon quantum well infrared photodetectors

Two-photon quantum well infrared photodetectors (QWIPs) involving three equidistant subbands take advantage of a resonantly enhanced optical nonlinearity, which is six orders of magnitude stronger than in a bulk semiconductor. This approach results in a sensitive device to measure quadratic autocorrelation of mid-infrared optical pulses from modelocked quantum cascade lasers, nonlinear optical conversion, and free-electron lasers (FEL). We report on autocorrelation measurements at wavelengths in the mid-infrared and Terahertz regimes using ps optical pulses from the FEL at the Forschungszentrum Dresden Rossendorf. In particular, quadratic detection at wavelengths around 5.5 μm is still possible at room-temperature, which is crucial for applications in practical systems. We also report on a two-photon detector which works below the Reststrahlen band at 42 μm (7.1 THz).