G-band T-type Staggered Double-vane Traveling Wave Tube

Terahertz(THz)electromagnetic waves are in the ranging frequency of 0.1-10THz between the electromagnetic waves.Terahertz electromagnetic wave has the following characteristics:firstly,for most non-metallic media it has a strong penetration;secondly,because of its high operating frequency,the wave has more advantages in absolute bandwidth compared to the devices whose center frequencies are lower.Therefore,there is no doubt that Terahertz electromagnetic wave has important scientific research value and broad application prospects whether in the field of national defense or industry.Since the 90s of last century,sheet electron beam has become a research hotspot with its low space charge field.And it is constantly being pioneering and innovative for that it can transmit large current and other unique advantages.Therefore,the study of sheet electron beam is becoming a trend.The electronic optical system is an important component of the sheet electron beam traveling wave tube,which has a great influence on the performance of the sheet electron beam traveling wave tube.At present,the main difficulty of sheet beam microwave devices lies in the transmission focus of sheet electron beam,so it is necessary to study the electronic optical system.The electronic optical system is mainly composed of electron gun and focusing magnetic system.Its function is as the energy source of the vacuum electronic device.It provides electron beam to meet the application requirements.This paper presents a novel G-band T-type staggered double-vane TWT.Firstly,the dispersion and coupling impedance characteristics are analyzed by using the electromagnetic simulation software HFSS,and the electronic optical system which is used for high frequency structure of the TWT is designed by the three-dimensional particle simulation software CST.Lastly,the beam-wave interaction process of this traveling wave tube is simulated by the same software.It is concluded that its performance is good.The main work of the paper is as follows:1.G-band T-type Staggered Double-vane slow wave structure(SWS)are studied.On the basics of normal staggered double-vane SWS,we propose a T-type staggered double vane SWS.By analyzing the effects of changes in various structural parameters on high-frequency characteristics,the dimensions of a T-type staggered double-vane SWS are determined finally.2.G-band sheet beam electronic optical system is studied.Firstly,an electron gun suitable for a T-type staggered double-vane slow-wave structure is presented based on the related theory of electron guns.By adjusting the structural parameters of the electron gun and by setting the particle monitor,The final working voltage of the electron gun25kV,working current 186mA,the cathode emission current density 81A/cm~2.At the same time,the laminar flow of electron beam at the waist position produced by the electron gun is good,the cross-sectional dimension is 0.3mm×0.1mm.After studying the generation of electrons,the focusing magnetic system required for sheet electron beam in the transmission process is also studied.In order to improve the Diocotron instability,an offset-pole periodic cusped magnet(PCM)focusing system is designed.The simulation result shows that the Diocotron instability of electron beam transmission has been improved and the electron beam transmission efficiency is up to99%in a 66.85-mm length drift tube.3.G-band T-type staggered double-vane TWT is studied.Because the input-output coupler play a very important role in the work of the entire traveling wave tube,an input-output coupler with a very low reflection coefficient is designed first,and the transmission characteristics of the structure are analyzed.At this point,the three-dimensional calculation model of the entire traveling wave tube has been fully presented.For the complete traveling wave tube,the 3-D particle simulation software CST is used to perform the beam-wave interaction calculation for the center frequency of 220GHz.Combined with the resulting performance charts,the final transmission performance and amplification performance of the TWT are analyzed in detail.