变参量Wiggler FEL的三维非线性理论

Three-Dimensional Nonlinear Theory of Tapered Wiggler FEL

本文建立了变参量Wiggler自由电子激光放大器的三维自洽非线性理论。考虑电磁波、电子注和Wiggler场三者均在三维空间中变化,忽略电子注的自身场和空间电荷效应,导出了带有变参量双绕螺旋Wiggler场和轴向导引磁场的矩形波导,轴对称电子注自由电子激光器的非线性互作用微分方程组。数值模拟表明:在适当位置逐渐减小Wiggler场的幅值或周期均能有效地提高电子注的能量转换效率。

The 3-D self-consistent nonlinear theory of free-electron-laser amplifier is developed in this paper. Considering the variations of the radiation fields, electron beam and wi-ggler fields in three-dimensions, and neglecting both the self field of the beam and the space charge effects, we derived a set of nonlinear differential equations for the rectangular waveguide configuration with a bifilar helical tapered wiggler. According to numerical simulations, the efficiency can be enhanced obviously when the amplitudes or periods of the wiggler begin to decrease gradually at suitable points.