Study On New Half-rectangular Ring Helix Traveling Wave Tube

With the rapid development of military electronic technology and the national economy,there is an urgent need for traveling wave tubes to have wider frequency bands,greater output power,higher frequencies,and smaller volume.The slow wave structure is the core component of the traveling wave tube,and its high frequency characteristics directly determine the performance parameters of the traveling wave tube.Traditional traveling wave tubes are difficult to meet these requirements due to factors such as large volume,low heat dissipation capacity,high processing difficulty,and low efficiency.Compared with the cylindrical electron beam,the sheet electron beam has become a more ideal radiation source for millimeter wave devices because of its own advantages such as lower space charge effect,larger current and higher power.Because of this,exploring new slow-wave structures that are compatible with micromachining technology(MEMS)and facilitate interaction with sheet electron beams has naturally become one of the mainstream development directions for current traveling wave tubes.For example,planar spirals,microstrip meander lines,and deformed meander waveguides.Based on this idea,on the basis of in-depth and detailed research and exploration of the helix slow wave structures,a new type of slow wave structure half-rectangular ring helix slow wave structure is proposed.In this paper,the slow wave characteristics,RF transmission characteristics and beam wave interaction characteristics are studied by computer simulation.The main work and innovations are as follows:1.A new type of half rectangular ring helix slow wave structure which can interact with sheet beam is proposed.The structure has the advantages of flat dispersion,large coupling impedance,compatibility with micro machining technology,and easy to batch fine machining.It is suitable for millimeter wave slow wave structure and microwave power module.2.The influence of different structure size parameters on the high frequency characteristics of the half rectangular ring helix is studied.The comparative analysis of the dispersion and coupling impedance characteristics between the half rectangular ring helix and the half circular ring helix is completed.Through comparative analysis,it is found that,in the case of similar dispersion characteristics,the coupling impedance of the half rectangular ring helix structure is higher than that of the half circular ring helix structure.The input-output structure of the half rectangular ring helix structure is designed,and the transmission characteristics are measured.The simulation results indicate that the reflection of the slow wave system is small and the transmission performance is good.3.The S-band circular electron beam half rectangular ring helix TWT is designed.Compared with the conventional half circular ring helix structure,in the case of similar dispersion characteristics,the same electrical parameters are used.The particle simulation results show that in the frequency range of 2.5-3.4GHz,the half rectangular ring helix TWT produces output power greater than 600 W,and the maximum output power reaches 1028 W.Compared with the half circular ring helix TWT,the maximum saturated output power is increased by about 14%,and the interaction length is shortened by about 18.5%.4.A 140 GHz sheet beam half rectangular ring helix TWT is designed.Under the same structural parameters,this paper compares it with the rectangular helix TWT.The simulation results of high frequency characteristics show that the half rectangular ring helix slow wave structure has lower phase velocity and similar dispersion flatness compared with the rectangular helix slow wave structure,and this new structure has higher coupling impedance almost in the whole working frequency band.The results of particle simulation show that in the frequency range of 120-166 GHz,the output power of the half rectangular ring helix TWT is more than 30 W,the output power at 140 GHz is 40 W,and the corresponding gain is 26.02 dB.Compared with the rectangular helix TWT,the output power of the half rectangular ring helix TWT in the frequency band of 100-162 GHz is greatly improved,and the power at 140 GHz is increased by 54%.