A three-dimensional nonlinear beam-wave interaction theory for common traveling wave tubes

作者:Yan, Weizhong*; Hu, Yulu; Tian, Yunxian; Peng, Weifeng; Li, Jianqing; Li, Bin
来源:Journal of Electromagnetic Waves and Applications, 2015, 29(16): 2178-2190.
DOI:10.1080/09205071.2015.1082440

摘要

A three-dimensional (3-D) nonlinear theory model of beam-wave interaction for common traveling wave tubes (TWTs) is described. The equation governing the amplitude of electromagnetic wave is derived analogously to Poynting's theorem. The electron dynamics are treated using the 3-D Lorentz force equations. RF space charge fields are obtained from solutions of the Helmholtz equations. In the model, the RF field profiles for cold structure are represented by the digitized RF field calculated by a finite-element software, HFSS. Because the digitized RF field can be obtained in the same way, the 3-D simulation code can be used to simulate common TWTs, such as helix TWTs, coupled-cavity TWTs, and even the folded waveguide TWTs. Results from the 3-D code are compared with those from 1-D code, experiment and the existing analytical theories for three types of slow wave structures.