Study Of Millimeter Wave Trapezoidal Thread Backward Wave Tube

Backward wave tube is a kind of microwave devices, which can generates self-excited electromagnetic wave oscillation without additional input signal, Realizing electronic tuning in wide band range is its important characteristic.The volume ratio of the backward wave tube is the highest among all the chapter vacuum device, it is one of the most possible small THz sources, so its research has become one of the hot topic researched by experts home and abroad.This thesis mainly studies the trapezoidal slow-wave structure of backward wave tube, and comparing the influence of circular electronic channel trapezoidal slow wave structure and rectangular electronic channel trapezoidal slow wave structure. By comparing the performance differences, we can choose the better size parameters of the structure. There are a number of parts in this paper:1. This article give an outline of the development of microwave vacuum devices, the development of backward wave tube, the structure of backward wave tube and the classify of backward wave tube. The study on backward wave tube trapezoidal slow-wave structure is based on the existing research results.2. Two important parameters of slow wave structure is studied, dispersion characteristics and coupling impedance related theory, particularly with respect to the calculation method of the coupling impedance theory.3. Realizing the cold cavity simulation of circular electronic channels trapezoidal slow-wave structure and rectangular electronic channels trapezoidal slow-wave structure is by using CST software, without electronic simulation. This article compares the difference of two structure in Dispersion Characteristics and Coupling Impedance and analysis the effect of size parameters on the Dispersion Characteristics and Coupling Impedance. The Dispersion Characteristics of circular electronic channels is more flat than the Dispersion Characteristics of rectangular electronic channel,the Coupling Impedance values of circular electronic channels is higher than rectangular electronic channel. The Dispersion Characteristics and coupling impedance of Circular electronic channels is highly affected by the size.4. Realizing the thermal cavity simulation of circular electronic channels trapezoidal slow-wave structure and rectangular electronic channels trapezoidal slow-wave structure is by using PIC particle simulation software to simulate wave interaction. This paper compares the difference of two structures on the output power, output efficiency and frequency, and analysis the effect of change the working voltage on output results. Under 6.8 k V and 0.056 A, the output power of circular slow-wave structure is 1.9 W, its output efficiency is 0.5%.When the working voltage changes between 5.8k V and 7.2k V, the bandwidth is 1.2 GHz. Under 6.8 k V and 0.02 A, the output power of rectangular electronic channels trapezoidal slow-wave structure is 35.7m W, output efficiency is 0.02%. When the working voltage changes between 5.8k V and 7.2k V, bandwidth is 4 GHz. The output spectrum of two structures are very pure, there is no interference. The output power and output efficiency of circular structure is higher, but its bandwidth is more narrow, it is the inevitable result of the pursuit of high power.