Study Of Novel Staggered Slow Wave Structure Traveling Wave Tube

With the increasingly widespread application of terahertz wave in broadband communications,biomedicine and national defense security,research on terahertz radiation sources has become a key issue in promoting the development of terahertz technology.Vacuum electronic devices(VEDs)are currently one of the most effective technologies for broadband high-power terahertz sources and amplifiers,among which the traveling wave tube(TWT)is the most widely used broadband high-power amplifier.The performance of the TWT depends heavily on the slow wave structure(SWS),which is the key component of TWT.However,as the operating frequency increases,the SWS is faced with problems such as small structure size,high transmission loss and low interaction impedance.To solve these problems,three novel staggered SWSs are proposed in the thesis based on staggered double gating(SDG)and sine waveguide(SW),which are two common staggered SWSs,and their operating characteristics are investigated in depth.Firstly,a modified staggered double gating(MSDG)with dual sheet beam tunnels is proposed in the thesis,which has larger electron beam size,higher interaction impedance and wider operating bandwidth compared with the traditional SDG.The beam-wave interaction simulation results show that the W-band TWT based on the MSDG can achieve the maximum output power of 561 W and the maximum electron efficiency of7.62% at 86 GHz,with a 3 d B bandwidth of 44 GHz.Secondly,a modified sine waveguide(MSW)suitable for interacting with elliptical beam is proposed in the thesis,which has a higher interaction impedance,a wider operating bandwidth and an elliptical-like electron beam tunnel than traditional SW.The simulation results of the beam-wave interaction show that the G-band TWT based on the MSW can produce the maximum output power of 151 W at 220 GHz with the corresponding electron efficiency of 4.85% and a 3 d B bandwidth of 60 GHz.Finally,a segmented staggered double gating(SSDG)combining the features of SW and SDG is proposed in the thesis,which has a higher interaction impedance than the traditional SW while maintaining the same loss level.The beam-wave interaction simulation results show the 340 GHz TWT based on the SSDG can provide the maximum output power of 32.8 W and the maximum electronic efficiency of 2.84% at 340 GHz,with a 3 d B bandwidth of 89 GHz.In summary,three novel staggered SWSs are proposed and investigated in the thesis,which provide the technical reserves for the development of terahertz TWT and have the positive effects to the development of terahertz technology.