Research On High Frequency Structure For Ka-band High Power Sheet Beam Traveling-Wave Tubes

Among various microwave sources,traveling wave tube(TWT)is an important type of microwave tube widely used in communication satellites,military radar,and electronic countermeasures.In recent years,ribbon electron beam TWTs have become a research hotspot for high-power devices due to their advantages of high current intensity,low current density,and smaller space charge force compared to traditional circular electron beam TWTs.The trapezoidal staggered double vane waveguide slow-wave structure of ribbon electron beam TWT has the characteristics of low transmission loss,small reflection,easy processing,and a natural ribbon electron beam channel.Based on this,this thesis selected a new type of trapezoidal staggered double vane waveguide slowwave structure ribbon electron beam TWT for in-depth research.The main work and innovation points of this thesis are as follows:1.Conducted an in-depth study of the field structure,dispersion characteristics,and coupling impedance of the trapezoidal staggered double vane slow-wave structure,and applied this structure to the TWT.The thesis proposed a slow-wave circuit transition structure and input-output structure suitable for this type of TWT,ensuring the efficient and stable operation of the TWT slow-wave structure in the Ka band through optimization of the structure’s reflection coefficient,dispersion characteristics,and coupling impedance.2.Conducted design research on a high-power ribbon electron beam TWT operating in the Ka band.Based on the previous research,the high-frequency transmission system of the trapezoidal staggered double vane TWT was designed,including the slow-wave structure,ridge waveguide input-output coupling structure,Bragg structure,and the slow-wave structure using phase velocity jump technology.A 30 GHz trapezoidal staggered double vane waveguide TWT was designed,with a total length of approximately 234 mm,operating voltage of 63 k V,operating current of 5.6A,and an output power greater than 60 k W and a gain over 20 d B in the working frequency band of 28GHz～32GHz.3.Designed a sapphire box window structure for the Ka band,with BJ320 standard waveguides on both sides and a sapphire window.The simulation test showed that the standing wave ratio of this box window structure was less than 1.3 in the frequency band of 28～32GHz.4.Conducted thermal analysis and cooling research on the high-power operation of the trapezoidal staggered double vane ribbon electron beam TWT at the simulation level,due to the high-power characteristics of this TWT.The simulation analysis showed that the TWT had a heat loss power of nearly 1k W under working conditions,and the temperature rise under water cooling was within an acceptable range.The temperature distribution of the window structure was also analyzed,and the power capacity of the box window was found to meet the design power of the TWT.5.Briefly introduced the manufacture process of the high-frequency system.An experiment is processed on the assembled parts and the experiment result is analyzed.The experiment results fits the simulated results well.