Millimeter Wave Dielectric Loading Trapezoidal Slow-wave Structure Characteristic Research

As an electric vacuum device, Traveling-Wave Tube (TWT) has unique advantages in many applications. Researchers have already conducted concrete work in this area, thus relative mature theory has been established. In order to improve the performance, its structure must be studied and a better new structure could be proposed based on theoretical analysis, simulation and experiment.Based on existing correlation study of TWT slow wave structure, this thesis proposes dielectric-loaded ladder slow wave structure. According to simulation provided by CST Microwave Studio, proposed structure has slower phase velocity, which could contribute to beam-wave interaction in cooling cavity. In thermal cavity, higher gain is obtained using3D PIC simulation software. The main work is as below:1. Study of related theories mainly include of coupling impedance and dispersion characteristic of TWT. Linear and non-linear theory is also generally introduced.2. Performs cooling cavity emulation on ladder slow wave structure. Change tendency of dispersion characteristic and coupling impedance corresponding to change of structure has been obtained based on analysis of simulation results.3. Performs cooling cavity emulation on dielectric loaded ladder slow wave structure. Change tendency of dispersion characteristic and coupling impedance corresponding to change of width and dielectric constant of dielectric loaded has been obtained based on analysis of simulation results. On the basis of investigation of energy input and output port, a proper port configuration plan has been proposed. Besides, transmission parameters and the loss have been examined in cooling cavity.4. Takes thermal cavity emulation dielectric loaded ladder slow wave structure. Its gain is30.6dB and efficiency is11.6%. The output spectrum is pure and no clutter interference. The bandwidth is1GHz. This slow wave structure thermal cavity gain is higher, but bandwidth slightly is narrower. This is also the general couple cavity slow wave structure characteristics. System noise situation is observed when closing input signal. The result proves that noise power is very low.