Electromagnetic field’s transmission attenuation in 345 GHz folded waveguide traveling-wave tube

The equivalent-conductivity method is applied to the simulation work of electromagnetic transmission attenuation for 345 GHz FWG-TWT(folded waveguide traveling-wave tube). The paper studies the cold model of slow-wave structure and does research on the big factors which influence transmission attenuation, such as the beam tunnels diameter, processing roughness. A big beam tunnel or a large roughness will result in serious electromagnetic attenuation. The paper also studies the hot model of slow-wave structure, and analyzes the effects of electromagnetic attenuation on gain, bandwidth, best length of slow wave structure. Results show that electromagnetic attenuation causes gain reduction and bandwidth decreases.