Design And Experience Research Of W-band Sheet Beam Electric Optical System

As a traditional O-type vacuum electronic device,the research of travelling wave tube(TWT)in millimeter wave band is relatively mature and plays an irreplaceable role in the field of vacuum electronics.With the development of industrialization,the requirements of higher power and efficiency are the goal of vacuum devices in the future.Therefore,the research on high-power and high-efficiency TWT is certainly necessary in practical significance and value.TWT can be divided into two parts: electric optical system and high frequency slow wave structure(SWS).In order to reach the goal of high output power,on the one hand,sheet electron beam,which makes the current increase and the space charge field decrease,is chosen to replace the traditional circuit electron beam.It is more suitable for the beamwave interaction to improve the gain and output power.On the other hand,high frequency system is designed by the staggered double-vane SWS,whose advantages such as good heat dissipation performance,simple geometry structure,moderate dispersion characteristics and high interaction impedance are useful for high-power TWT.Based on the sheet electron beam and the staggered double vane SWS,the paper present the design,assembly and test of a W-band high-power TWT with theoretical analysis,simulations and experiments.The main contents are as follows:1.After the analysis of dispersion characteristics and interaction impedance,the staggered double vane structure is proposed to apply on TWT with the study of corresponding transaction structure for circuit,the input and output couplers and box-type windows.Then the transmission characteristics are tested after high speed computer numerical control(CNC)mill processing and assembling.The “cold” test results verify part of simulations and lay a solid foundation for the development of sheet beam vacuum devices.2.A sheet electron gun with large compression ratio and large current is designed and machined after analyzing the idea of pierce electron gun and the distribution of space charge field.A small tunable periodic cusped magnetic(PCM)focusing system is simulated and pre-assembled after the calculation of sheet electron beam between space charge field and PCM focusing magnetic field.Such study supplies an integrated scheme for sheet electron optical system and gives a powerful base for future investigation.3.A W-band sheet beam TWT is equipped with high frequency,sheet electron gun and PCM focusing system mentioned earlier.It offers experimental guidance for the application of sheet beam electron optical system in W-band and gathers experience for the manufacture of high-power sheet beam TWT.