室温脉冲螺旋Wiggler磁体和大电流脉冲电源的研究

本文研究了适用于自由电子激光器的室温脉冲螺旋Ｗｉｇｇｌｅｒ磁体，对其设计构思、磁场特性和设计参数进行了分析和计算。作者在文中还研究并设计了螺旋Ｗｉｇｇｌｅｒ磁体的大电流宽脉冲供电电源；分析了脉冲电流的时间特性对产生自由电子激光的影响程度。     

自由电子激光中自发辐射光脉冲的自干涉现象

本文用格林函数法,计算了螺旋磁场自由电子激光中单脉冲电子注的自发辐射;结果表明,电子注的有限长度会引起自发辐射光脉冲的自干涉现象。     

大功率长脉冲速调管电子枪的计算机辅助设计

本文简介了大功率长脉冲速调管电子枪计算机辅助设计的结果。这种设计方法和设计程序也可用于自由电子激光用的热阴极高亮度注入器设计中。     

超短脉冲激光在导体中穿透深度的估算

对超短脉冲激光辐导电介质之间的相互作用进行了理论研究,在研究中把脉冲作为按泊松分布光子流,而介质被当作一种利用逆韧致效应来吸收光子的准自由电子系统对强超短脉冲激光辐射在导电介质中的穿透深度进行了估算。     

自由电子激光短脉冲滑移效应分析

对低增益及高增益自由电子激光的短脉冲滑移(slippage)效应分别进行了分析。对电子与光脉冲初始均为矩形脉冲时的情况,得到了相应的小信号光场解析式。     

脉冲激光探测电路设计

脉冲激光探测电路的设计是激光应用领域的重要内容,根据脉冲激光信号的特点,从探测能力、响应时间、稳定性三方面对脉冲激光探测电路的设计进行研究,重点论述了光电探测系统组成的三个重要组成部分：光电探测器、光电转换电路和探测器偏置电路。深入分析了光电探测器的选型、利用电阻进行光电转换电路的特性以及利用跨导放大器进行光电转换电路的特性,对于激光探测系统的设计有一定参考价值。     

自由电子抽运X射线激光的理论探讨

X射线激光是激光物理与等离子物理中的一个重要研究领域。目前，X射线激光研究多采用毛细管放电、高功率激光的多脉冲和短脉冲等抽运方式，而且绝大多数研究局限于软X射线波段。借鉴自由电子激光器的组成结构，提出一种产生X射线激光的新方案：用钨制成毛细管的空心电极取代自由电子激光器内的摇摆器，内充特定金属蒸气，如铜蒸气之类，使自由电子激光器变成自由电子抽运X射线激光器。运用电子碰撞电离、强流粒子束平衡体系理论方程与等离子复合特性等理论对这种新型X射线激光器的工作原理及其方案的可行性作了进一步的理论分析与探讨。     

红外纳秒激光脉冲在光纤中传输特性研究

为了提高激光时间波形测量系统的抗干扰能力,建立了激光脉冲在光纤中的传输物理模型,分析了纳秒脉冲在光纤中的线性传输特性,对影响脉冲传输特性的因素进行了系统评价.采用空气与光纤传输进行比对的方法,实验测试了激光脉冲经过不同长度的单模和多模光纤传输后的脉冲波形,得到脉冲展宽在允许的测量误差范围内所需的阈值条件.结果表明,该研究对神光-Ⅲ主机激光脉冲时间波形测量的设计具有重要的意义.     

调QNd：YAGE脉冲激光：光纤耦合与传输特性的研究

研究了调ＱＮｄ：ＹＡＧ脉冲激光－光纤耦合效率与传输特性，测量了激光损伤阈值，研究了入射激光束参数对激光损伤阈值和耦合效率的影响，在此基础上设计了耦合光学系统，对１０ｎｓ的激光脉冲，从光纤输出的激光脉冲的能量密度达１２Ｊ／ｃｍ＾２，对准静态Ｎｄ：ＹＡＧ脉冲激光，从光纤输出的激光脉冲的能量达３．５Ｊ可以满足激光刻字和激光焊接的要求。     

红外纳秒激光脉冲在光纤中传输特性研究

为了提高激光时间波形测量系统的抗干扰能力,建立了激光脉冲在光纤中的传输物理模型,分析了纳秒脉冲在光纤中的线性传输特性,对影响脉冲传输特性的因素进行了系统评价。采用空气与光纤传输进行比对的方法,实验测试了激光脉冲经过不同长度的单模和多模光纤传输后的脉冲波形,得到脉冲展宽在允许的测量误差范围内所需的阈值条件。结果表明,该研究对神光-Ⅲ主机激光脉冲时间波形测量的设计具有重要的意义。     

Tapered-wiggler free-electron laser optimization

Recent threshold analysis of free-electron lasers (FEL's) has indicated that the use of tapered wigglers may allow substantial single-pass electron energy extraction. This has led to a current experimental verification program in which the tapered wiggler is a critical element. This paper discusses the wiggler optimization for single-pass systems in the limit of low gain and extraction. The interaction of wiggler magnet and photon beam parameters is examined to identify configurations which produce maximum electron kinetic energy extraction for a given photon power. The analysis includes both permanent and electromagnet wigglers.     

A novel small-period wiggler and simulations of its free-electronlaser

A small-period wiggler constructed of edgy-wound bifilar-helical conducting sheets with ferromagnetic cores, which is intended for free-electron lasers, is presented. The performance characteristics of the wiggler fields with a 100 mm period are measured. A field as high as 1500 G has been obtained. Free-electron lasers with this small-period wiggler have been investigated numerically with a three-dimensional nonlinear theory. Simulation results estimated that a radiation power of 20.2 MW and a frequency of 170 GHz with an efficiency of 5.1% can be obtained. It is feasible to make Raman free-electron lasers with this type of wiggler operating in the millimeter and submillimeter wavelength range with a relatively low electron energy (<500 keV) beam     

FEL gain reduction due to wiggler errors

We report the results of a study comparing an analytical theory of wiggler errors in free-electron lasers (FEL's) to a numerical simulation. The different mechanisms of reduction in FEL gain due to wiggler errors are reviewed, and in each case analytical results are compared with computer simulation and shown to be in good agreement. We present a study of the proposed UV FEL user facility at BNL and determine the implications of the wiggler errors on the FEL design     

A solenoid-derived wiggler

A novel wiggler design for use in free-electron lasers (FELs) is proposed, consisting of a staggered array of magnetic poles situated inside the bore of a solenoid. The resultant field pattern consists of a periodic transverse magnetic field on axis, as well as a longitudinal guide field. Such a wiggler has several advantages: the longitudinal field acts to confine the electrons near the FEL axis, high fields can be attained at short wiggler periods, the field strength is easily varied, and fabrication and testing of the wiggler are relatively easy. It is planned to use this wiggler design in a far infrared FEL to be built at Stanford University     

Effect of electron beam temperature on the gain of a collective free-electron laser

At sufficiently low beam currents, electron beam temperature effects cause the gains of collective (Raman) regime free-electron lasers to be lower than the predictions of cold beam theory. This gain degradation has been measured as a function of the beam current, the wiggler magnetic field, and the interaction frequency. The measurements are used to estimate the electron beam temperature, and the estimated temperature is close to the temperature predicted by numeric simulations.     

自由电子激光器中相对论电子与wiggler同轴性的要求

讨论了自由电子激光器中,相对论电子束与wiggler的轴线有小夹角时激光增益的变化,并给出了最大容许偏角。     

永磁Wiggler磁场的设计和小周期数装置的实验

Wiggler磁场是自由电子激光器的重要组成部分。根据计算分析和自由电子激光器的总体设计要求,提出了Wiggler磁场的设计考虑。研制出小周期数装置,在改变磁隙、周期、磁块尺寸以及材料的情况下进行了测量,同时测量了磁场的正弦分布。结果表明,设计并研制的小周期数Wiggler磁场满足总体要求,可用于自由电子激光器。     

A staggered-array wiggler for far-infrared, free-electron laseroperation

A staggered-array wiggler for a far-infrared free-electron laser (FEL) has been built at Stanford, and its magnetic properties have been tested. This type of wiggler has several desirable features: high wiggler field at short wiggler periods, wavelength tuning by a solenoid current, electron beam confinement by a solenoid field, and looser machining tolerances. A 10.8-kilogauss peak wiggler field has been measured at a 7.0-kilogauss solenoid field for a 1.0-cm wiggler period and a 2.0-mm gap. The small-signal gain has been calculated analytically and by computer simulation for a 0.5-m long wiggler. For an 8-A, 9-ps current pulse and a 3.3-MeV electron beam, 5-dB gain is predicted. Twenty- to thirty-percent wavelength tuning can be achieved by adjusting the solenoid field and still maintain reasonable small-signal gain. The pulsed-wire technique was employed to test the field uniformity of this novel wiggler, and the measured field variation was about 1%     

Free-electron lasers with electromagnetic standing wave wigglers

A detailed analysis of the electromagnetic standing wave wiggler for free-electron lasers (FEL's) is conducted for both circular and linear wiggler polarizations, following a single-particle approach. After determination of the unperturbed electron orbits in the wiggler field, the single-particle spontaneous emission spectrum and subsequently the gain in the low gain Compton regime (using the Einstein coefficient method) are explicitly calculated. This analysis results in a clear understanding of the resonance conditions and the coupling strength associated with each resonance of this type of FEL. In particular, a striking feature obtained from this investigation is that the electromagnetic standing wave wiggler FEL, under certain circumstances, exhibits a rich harmonic content. This harmonic content is caused by the presence of both the forward and backward wave components of the standing wave wiggler field. In addition, the nonlinear self-consistent equations for this type of FEL are also presented, permitting further investigation of it by the theoretical techniques and numerical codes developed for conventional FEL's.     

电子束的发散性对自由电子激光器输出性能的影响

研究表明,进入Wiggler场的相对论电子束的发散角增大,将降低自由电子激光器的增益,但小量的发散角可提高激光器的输出功率。最大容许的发散角由激光振荡条件决定。