椭圆波导FEM放大器的非线性特性研究

Nonlinear study of the elliptical wave-guide FEM amplifier

以椭圆波导、平板摇摆器为 FEM放大器的模型 ,导出了自洽的注波互作用三维非线性方程组。在此基础上编制了相应的程序。利用该程序分析了 FEM放大器的饱和功率、效率以及带宽等高频特性。考虑了摇摆器渐变、空间电荷波、电子初始速度零散对高频特性的影响。

A set of coupled nonlinear three-dimension differential equations for the FEM amplifier with elliptical wave-guide and planar wiggler is derived. Based on these equations, a universal numerical simulation program is developed independently. The characteristics of this FEM including the evolution of power, saturation efficiency and bandwidth are investigated using the numerical method. Electron momentum spread ,space-charge and wiggler taper are also considered. Electron beam is modeled to adiabatically inject by allowing the wiggler amplitude to increase from zero to a constant amplitude and the space-charge is analyzed in terms of G-T mode expansion method. The results show that saturated output power is 360kW, efficiency is up to 9.2% using wiggler taper and 3dB bandwidth is 6.9% of the FEM amplifier operating at 94GHz.