螺旋线行波管三维频域非线性注波互作用的计算

基于行波管中慢电磁行波的周期传输特性和能流坡印廷定理，考虑高频结构的衰减、切断、螺距的渐变与跳变对互作用的影响，建立了螺旋线行波管三维场论非线性自洽工作方程组.通过傅里叶展式将时域中的电流变换为与频率相关的交流电流分量，采用等离子体粒子模拟的方法，求解离散化的亥姆霍兹方程获得空间电荷场的三维数值解.计算三维电子轨迹，得到精确的互作用后的电子能谱结构，为多级降压收集极的设计提供关键参数.计算结果与电子所Ku波段的测试值比较具有较好的一致性，并分析了互作用后的电子能谱结构，与多级降压收集极的实验基本符合. 关键词： 行波管 非线性注波互作用 空间电荷场 等离子体粒子模拟

Calculations of three-dimensional frequency-domain nonlinear beam-wave reaction for helix traveling wave tubes

Considering the attenuation, severing, taper and magnetic admittance, the self-consistent working equations are presented, which describe the operation of 3D nonlinear beam-wave interaction for helix traveling wave tube based on periodic structure characteristic and Poynting's theorem. Using Fourier transform from time-dependent current to ac current consisting of a series of wave frequencies, the space fields are obtained through weighing charge particles to fixed meshes with the help of particle_in_cell technique. The model also computes 3D electronic tracks and helix interception current, the electronic energy spectrum of spent beam are represented, which is helpful for designing multistage depressed collector （MDC）. Calculation of Ku-band TWT in IECAS was shown to be in better agreement with experiment, including output power and analysis of MDC.