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用单粒子理论三维毫米波方形波导自由电子激光放大器程序FEL-2-A,对由可实现的摇摆器-线极化平面Wiggler外加四极子聚焦或平面抛物极面Wiggler-组成的自由电子激光放大器的非线性演变进行了计算、分析并同实验结果作了比较。FEL-2-A程序是由一组耦合非线性微分方程组构成的。它包括用来描写在无损、矩形波导中TEmn和TMmn 模自洽演变的光场模拟方程和用来描述电子束的轨迹及其与光场相互作用的电子模拟方程。文中采用了傍轴近似以及绝热慢变近似。不考虑电子束群聚的纵向空间电荷力。电子束在相空间中(γ,ψ,χ_j,υ_(xj),j=1,2)的初始分布由蒙特卡罗随机抽样给出。FEL-2-A的数值模拟结果已经与LLNL的实验结果和FRED程序的模拟结果进行了比较(TE01模),其间的符合程度是十分令人满意的。此外还用此程序研究了Wiggler的不同极化形式,不同注入功率及各种其他相关参量对FEL输出功率的影响,所有这些对4MeV FEL放大器的设计和实验都具有一定的参考意义。在该程序中,考虑空间电荷力对输出功率的影响和使用共振粒子近似方程设计Wiggler的振幅和周期,使得Wiggler参数与电子束的能量相匹配以提高输出功率的计算,分析以及同实验结果的比较将在另外的文章中给出。
Using a single-particle theoretical three-dimensional millimeter-wave square waveguide free electron laser amplifier program FEL-2-A, a free-electron laser consisting of a realizable wiggler plus linearly polarized planar Wiggler quadrupole focus or planar parabolic pole face Wiggler- The nonlinear evolution of the amplifier was calculated, analyzed and compared with the experimental results. The FEL-2-A program consists of a set of coupled nonlinear differential equations. It consists of a light-field modeling equation describing the self-consistent evolution of TEmn and TMmn modes in a lossless, rectangular waveguide and an electronic modeling equation describing the trajectory of the electron beam and its interaction with the light field. In this paper, the paraxial approximation and the slow adiabatic approximation are used. Does not consider the electron beam cluster longitudinal space charge. The initial distribution of the electron beam in the phase space (γ, ψ, χ_j, υ_ (xj), j = 1,2) is given by Monte Carlo random sampling. The numerical simulation results of FEL-2-A have been compared with the experimental results of LLNL and the simulation results of FRED program (TE01 mode), the degree of coincidence between them is very satisfactory. In addition, this program is also used to study the influence of Wiggler’s different polarization forms, different injection powers and various other related parameters on the FEL output power, all of which have certain reference significance for the design and experiment of the 4 MeV FEL amplifier. In this program, considering the influence of space charge on output power and designing the amplitude and period of Wiggler using the resonance particle approximation equation, the Wiggler parameter is matched with the energy of the electron beam to improve the calculation and analysis of the output power. The comparison will be given in a separate article.