Research On Traveling-wave Tubes With Novel Rectangular-ring Vertex Double-bar Slow-wave

Conventional circular helix SWS has the advantages of broadband and low dispersion,and is widely used in the field of broadband medium-power TWT.However,as the operating frequency enters the millimeter wave band,the size of the SWS decreases sharply,and circular helix is difficult to be accurately processed in batch due to its three-dimensional structure characteristics.Meanwhile,the increase in the power of the TWT is affected by factors such as back-wave oscillation and heat dissipation.The ring double-bar SWS is a kind of SWS proposed in recent years,which is suitable for the development of high power TWT.Studies have shown that:compared to the traditional ring single-bar(ring-bar),the ring double-bar SWS has a larger operating frequency band and a higher phase velocity,as well as a larger cross-sectional size.The SWS of the TWT can work at high voltage,and at the same time,a larger-sized electron beam can be used for beam-wave interaction.However,under the working conditions of large voltage and current,the relative strong space field of the pencil beam is not beneficial to the stability of the TWT.At the same time,the interaction impedance of the ring double-bar SWS is relatively small,which hinders the increase of the output power of the TWT.So,a novel rectangular-ring vertex double-bar SWS is proposed.The main work and innovation points are as follows:1.a new kind of rectangular-ring vertex double-bar SWS is proposed.This new kind of structure has the comprehensive advantages of flatter dispersion,higher coupling impedance and easy processing.2.The influence of the parameters of the SWS on the high frequency characteristics is studied by 3D electromagnetic simulation software HFSS.Meanwhile,compared with the circular ring double-bar SWS,the new structure has flatter dispersion and higher coupling impedance,which is beneficial to increase the output power and 3d B bandwidth of the TWT.3.Research on the input and output coupling device of the rectangular-ring double-bar slow wave structure is carried out,and an extended coplanar metal plate is designed.Based on the new input and output structure,S11<-15 d B can be in the range of f=20-40 GHz.4.The beam-wave interaction research was carried out.Under the same working voltage and working current conditions,the rectangular-ring double-bar traveling wave tube can obtain 1148 W peak power,and the corresponding gain electronic efficiency is 40.6d B,22.9%,respectively.Compared with the equivalent circular ring double-bar SWS traveling wave tube,the peak power is increased by 45.5%,and the electronic efficiency is increased by 45.9%.