| The vacuum electronic devices(VEDs)are devices in which electrons interact with electromagnetic waves in vacuum and amplify electromagnetic waves.In recent years,with the development of VEDs to the millimeter wave and sub-millimeter wave,the dimension of the traditional O type VED is getting small due to the size effect,which would arise many problems.At this time,sheet electron beam(SEB)VEDs can be extended in the lateral direction and can increase the input power,thus exhibiting great advantages at high frequencies.Three Slot Staggered Ladder(TSTL)structure is an all-metal slow wave structure(SWS).In addition to simple structure,easy processing,and good heat dissipation capacity,its most outstanding advantages are its large size of the SEB channel and high output power.So,the SWS has been favored by many researchers.The main research contents of this paper are as follows:(1)A X-band SEB traveling-wave tube(TWT)based on TSTL coupled-cavity slow wave structure(CC-SWS)is designed.Firstly,the high-frequency characteristics of TSTL SWS are analyzed by HFSS in detail.Then,a well-matched input/output coupling system that solves the problem of energy coupling between the SWS and the external circuit is designed.The beam-wave interaction is studied.The results obtained by CST simulation show that the SEB TWT can produce output power over 15.5kW within the bandwidth ranging from 9.5GHz to 10.5GHz,and the maximum output power is 26.45kW at 10GHz,corresponding to a gain of 27.23dB and electron efficiency of 25.43%.Finally,the transmission characteristics of the high-frequency structure are tested.The test results basically meet the design requirements..(2)A Ka-band SEB TWT based on TSTL CC-SWS is proposed.This chapter proposes a new method of loading distributed attenuator.From the simulation results of the transmission characteristics of high-frequency systems,this new distributed attenuator can effectively reduce the transmission parameters and thus effectively suppress oscillations.The beam-wave interaction results obtained by CST Particle Studio demonstrate that the output power is more than 5 kW in the frequency ranging from 31.5 to 35.5 GHz,and the maximum average output power is 10.15 kW at 33 GHz,corresponding to the maximum gain of 23.1 dB and electronic efficiency of 10.36%.Finally,in order to improve the electron efficiency and output power of the TWT,the phase velocity technology is applied.The results show that this TWT has output power of 12.09kW,electron efficiency of 12.34%at 33GHz,and these improvements of output power and electron efficiency are 1973W and 1.98%,respectively.(3)A W-band SEB TWT based on TSTL CC-SWS is studied in this chapter.The high-frequency characteristics of TSTL CC-SWS are analyzed.Well-matched input/output couplers that solve the problem of energy coupling between the SWS and the external circuit are designed.Finally,the beam-wave interaction was studied.The results show that the SEB TWT can produce output power over 1.27kW within the bandwidth ranging from 90GHz to 99.5GHz,and the maximum output power is 2.8kW at 96.5GHz,corresponding to the maximum electronic efficiency of 10.67%.(4)Based on the Ka-band SEB TSTL CC-SWS TWT,an electronic optical system that meets its requirements is designed.Firstly,according to the traditional axially symmetrical Pierce gun,a SEB gun suitable for the TWT is designed,which can produce the SEB with beam voltage of 19.6 kV,beam current of 5A,and cross-sectional dimension of 3×0.52 mm~2.Then,a small tunable periodic cusped magnet system is applied to focus the SEB,the simulation results of the beam transmission reveal that100%transmission efficiency in a 76-mm length drift tube is achieved.Finally,A new and non-axisymmetric structure multistage depressed collector(MDC)for sheet beam vacuum electronics devices is proposed.The new sheet-beam MDC has some advantages of simple structure,easy realization,high collection efficiency and no back-streaming,which lays the foundation for the high efficiency sheet-beam devices. |
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