The Research Of W-band High-power Pulsed Traveling Wave Tube

With the development of microwave theory and processing technology, the working frequency of microwave vacuum devices is rising. The number of W-band device which is one of the W-band microwave atmospheric window is also increasing.For the traveling wave tube, the helix traveling wave tube in the W-band structure is difficult in processing and assembly due to the smaller size. What’s more, its thermal performance is also poor. The coupled-cavity TWT has better thermal performance, and the output power is higher, but its bandwidth is narrow which limited the range of its applications.In this paper, I design a W-band folded waveguide traveling wave tube which works in a pulse mode. because of the potential folded waveguide. I carried out the following research and design.1. With theoretical analysis, I introduce the folded waveguide traveling wave tube slow wave structure and its design methods, design processes and related considerations.The simulation of cold test parameters and beam-wave interaction simulation, bandwidth, output power simulation results meet the design target.2.With theoretical analysis, I introduce the electron-optical system and ts design methods, design processes and related considerations. With the theory of Pierce, I design and optimize an electron gun by vaughan method. Through simulation, the electron gun current, cathode emission surface current density, and the radius of the electron beam meets the design target. I also design a periodic permanent magnet focusing structure as the magnetic system. Through simulation, the axial magnetic field,cycle length, the pole pieces saturation meet the requirements. And I simulate the electron gun and the magnetic system together, the result is good.3.I design the related parts of the TWT, including input and output waveguides,windows and the attenuator. With simulation and optimization, the final VSWR of all these structure is very low in a wide bandwidth.4.I find some problems in process and put forward some ways of solution. The problems such as the attenuator metallization. Whats more I introduce some advanced processing technology.5. I Complete the engineering drawing, the assembly of the entire tube and therelated tests.