3D Frequency Domain Nonlinear Beam-Wave Interaction of Coaxial Staggered Double-Grating TWT: A Simulation and Comparison Study

3D frequency domain nonlinear beam-wave interaction of coaxial staggered double-grating traveling wave tube (TWT) was mathematically modeled, theoretically analyzed by numerically solving the derived equations with CST code.The impact of the materials and structures on the wave attenuation behavior was investigated.The self-developed program based on the nonlinear model and equations more accurately describes the influence of the tapering/step attenuation on beam-wave interaction.The beam-wave interaction in a small cross-section model, because of limited computer capacity, was simulated with the nonlinear program and CST code, respectively.Moreover, the beam-wave interaction of the Ka-band TWT, designed with large cross-section, was simulated.The simulated results show that the new model works well and is capable of generating large power at a high frequency.We suggest that the results we reported be of some technological interest in development of coaxial staggered double-grating TWT with large cross-section.