一种SASE-FEL用摇摆器机制探讨

利用带电粒子在均匀等离子体中传播时,在其后激发的尾波场作为自发辐射自放大自由电子激光(SASE-FEL)的摇摆器,称为尾波摇摆器。分析了此摇摆器在工作机制及其相应的周期、场强度,根据SASE-FEL理论计算了其增益长度Lg,并和APS的SASE实验参数作了比较。     

电子在多层膜摇摆器中的辐射

提出了利用多层膜作自由电子激光器的摇摆器,利用虚光子和康普顿散射讨论了运动电子在多层膜摇摆器中的自发辐射。(Fe/Cr)N等铁磁-非磁层状材料的铁磁层之间存在反铁磁耦合,因此可以利用磁性多层膜制作自由电子激光器的摇摆器。考虑到静磁场的空间周期只有7.8nm,要精确计算电子在多层膜摇摆器中运动的自发辐射的波长和辐射功率就必须考虑电子的反冲。给出了运动电子在多层膜摇摆器中的自发辐射波长和辐射功率的精确计算表达式。结果发现,自发辐射波长和辐射功率表达式中都含有康普顿波长。     

静电摇摆器自由电子激光器的高次谐波分析

讨论了一种静电摇摆器中电子的自发辐射谱和高次谐波的增益 ,其形式与平面磁摇摆器中的类似。这种静电摇摆器可由等离子体流波纹产生。当存在轴向静电力时 ,高次谐波就可能产生     

等离子体尾波场摇摆器自由电子激光

自由电子激光的小型化和实现激光短波长一直是自由电子激光领域的研究热点,而短周期、强场摇摆器是解决此问题的行之有效的途径。文章分析了利用等离子体尾波场作为自由电子激光摇摆器的机制,推得自由电子的自发辐射谱,利用麦迪定在线阵列理论求得电子的受激辐射公式,得到小信号增益。     

一种高频高效自由电子激光潘尼混合器件

本文研究了直流和纵向摇摆器混合磁场中旋转运动电子束与潘民管电磁模式相互作用不稳定性的情况。研究指出指出这种不稳定性基于潘尼管的工作机理,但它工作在ω＝σｃ＋ｋｗｖ‖的混合频率上。因此这种器件具有高效率和高频率工作双重优点。在数值模拟中找到３６％的高效率。此外,其输出功率随摇摆器磁场具有连续可调性。     

大阪自由电子微光研究所的自由电子激光研究

大阪自由电子激光研究所由日本关键技术中心计划建议，计划结束后，由几个组织机构在此联合工作，该所的自由电子激光器有0.27-50μm以上宽阔的可调谐波长区，正用于各种研究领域。该装置除作了用户装置基本应用外，还努力向短波长扩展，提出了带微型摇摆器和种子源X射线的自放大自发辐射自由电子激光器方案，并在这方面进行研究，微型摇摆器的基础开发接近完成，种子源X射线将采用光产生的等离子体X射线，本文给出该所目前的研究状况。     

磁场误差对自由电子激光器增益的影响

用随机数构造了摇摆器磁场的误差分布．基于CAEPFEL的理论设计，研究了磁场误差对自由电子激光器增益的影响．     

大阪自由电子激光研究所的自由电子激光研究

大阪自由电子激光研究所由日本关键技术中心计划建立，计划结束后，由几个组织机构在此联合工作。该所的自由电子激光器有0.27-50靘以上宽阔的可调谐波长区，正用于各种研究领域。该装置除作为用户装置基本应用外，还努力向短波长扩展。提出了带微型摇摆器和种子源X射线的自放大自发辐射自由电子激光器方案，并在这方面进行研究。微型摇摆器的基础开发接近完成。种子源X射线将采用激光产生的等离子体X射线。本文给出该所目前的研究状况。     

一种由强光担任摇摆器的新型自由电子激光器及其增益分析

提出了一种由超短脉冲双光束担任摇摆器的自由电子激光器的原理及设计方案,并在单电子近似的基础上给出了计算其增益的联立方程组,以用于数值模拟.指出了实现一种紧凑、廉价的可调谐光源的可能性.     

纵向摇摆器磁场中的电子轨道

本文求解纵向摇摆器磁场加直流磁场中的电子运动方程,在直角坐标系中求得电子速度的严格解析解,并导出直角坐标和圆柱坐标中电子位置坐标的近似析解。同时用电子运动模拟计算进行了校验,指出近似解析解有较好的准确性。     

静电自由电子激光摆动器

静电自由电子激光使用静电摆动场代替静磁摆动场产生相干受激辐射。本文提出了一种静电自由电子激光摆动器。这种摆动器可以产生周期从3cm到5mm,辐值比较大的圆极化摆动场,有利于自由电子激光的进一步研究。     

Field Distribution of a Planar Electrostatic Wiggler and Modulation Effect on the Motion of Relativistic Electrons

A planar electrostatic wiggler is formed by two parallel metallic plates, where the upper-plate is corrugated with sinusoidal ripples and connected to a negative voltage and the lower-plate is smooth and grounded. The field distribution is mathematically derived in detail. It is demonstrated that this planar electrostatic wiggler can efficiently modulate the motion of relativistic electrons just as a magneto-static wiggler does in a free-electron laser. Results obtained here will provide basis to analyze the amplification mechanism of a fast wave by a relativistic electron beam in a planar electrostatic wiggler.     

Hybrid Planar Wiggler with a Period of 2 cm for Higher Harmonic FEL Lasing

A hybrid planar wiggler with a period of 20 mm has been studied as the simplest one which gives the strong field including some higher harmonic components by selecting proper sizes of the ferromagnetic and the permanent magnet. Small gap length of the wiggler and small width of permendur satisfy these conditions to a certain degree. Gain analysis of FEL suggests that for high wiggler field of K>1 ～ 1.6, higher harmonic gains are improved primarily due to its strong field, and for low wiggler field of K< 1 ～ 1.6, they are mainly due to the modification of the wiggler field distribution.     

Plasma Induced Wiggler Magnetic Field in a Cavity

The transformation of an elliptically polarized standing wave in a cavity by a suddenly and uniformly created plasma is discussed. Theoretical expressions for the plasma induced wiggler magnetic field as well as the frequency-upshifted standing wave are derived. By choosing appropriate values of the source wave parameters and plasma parameters, one can get wiggler magnetic field of desired magnitude, direction and wiggler wavelength. A few representative results are discussed.     

The Magnetic Field Distributions and Beam Propagation Properties of the Hybrid Coaxial Wiggler

In this paper a novel coaxial wiggler, the hybrid coaxial wiggler, is proposed. The analytical formula for magnetic field of the wiggler is derived, and the beam propagation properties are investigated numerically. The results show that the hybrid coaxial wiggler is scalable to small periods with high field amplitude, high beam current acceptance, and excellent transverse focusing properties.     

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%     

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     

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