| High power microwave electron vacuum devices are promising for both military and civilian applications.The most familiar and widely used devices among them are relativistic backward wave oscillators(RBWOs)and relativistic traveling wave tubes(RTWTs).It is an importance development direction for high power tubes to improve the power and frequency of the radiation,and using the sheet electron beam is a method worth trying.So,the researches about sheet electron beam RBWOs and RTWTs are of great values.This dissertation will describe and solve the problems during the design process of these sheet beam devices.The main contents and keys of innovation are as follows:1.Some theoretical researches about the single-grating rectangular waveguide,double-grating rectangular waveguide and staggered double-grating waveguide(with arbitrary dislocation)will be made.The general dispersive equation of these structures is obtained and its accuracy is verified.Additional,for the rectangular grating waveguides using in the sheet electron beam RBWOs and RTWTs,as the width of these structures are large enough,so another new solution method is given in this dissertation to get the dispersion equations of these structures.2.For the double-grating rectangular waveguide sheet beam RBWO,a new type of resonant reflector is proposed and designed.In order to solve the problem that the fundamental mode in this structure is antisymmetric,a solution that moves up the sheet beam to be closer to the gratings is put forward.By this method,the output power can be improved too.At last,this Ka-band sheet beam RBWO is developed,and an output power of 46.8MW at 31.1GHz is obtained in the experiment.3.For the single grating waveguide sheet beam RTWT,an E-bend input structure is put forward,which can solve the difficult problem that the electromagnetic wave cannot be cut-off in the sheet beam tunnel.A new type of transition structure between the wide rectangular waveguide and the SWS is proposed and a taper between the standard waveguide and the wide waveguide is designed,which can ensure improved transmission characteristics of high frequency system to suppress the self-exited oscillation and the generating of higher order modes.In the experiment,a method is put forward to adjust the synchronization between the electron beam and input signal.At last,this Ka-band sheet beam RTWT is realized,and a radiation of 1.21 MW at 35 GHz is tested.4.In order to improve the output power of the sheet beam RTWT,the concept of two-stage sheet beam RTWT is put forward.To solve the problem that the wave cannot be cut off in the sheet beam tunnel,a feasible attenuator is designed according to the practical parameters.The design of this two-stage tube is completed by simulation method,and when the input power is 11 kW,an output power of 19.5MW at 35 GHz is got,corresponding to a gain of 32.5dB and an efficiency of 15.6%.5.In the terahertz(THz)band,as the structure dimension will become smaller and the electron beam current and space charge effect will become larger,it is very hard to get high power radiation.So,the concept of two-stage,two sheet beam RTWT(SBRTWT)is put forward,which gives the possibility for high power THz output power.In this SBRTWT,a branch-guide energy coupler is used,which can couple the output power of the first-stage wide SWS to the second-stage wide SWS.At last,a two-stage 220 GHz sheet beam RTWT is finished by simulation method,and an output power exceed 70 MW is obtained.6.For the branch-guide coupler,a theoretical method based on the phase superposition principle is used to analyze this kind of coupler.A new physical model for this coupler is built,which is applicable for the branch-guide coupler with arbitrary width and arbitrary coupling coefficient.At last,a rapid design formula is obtained.Along with simulation method,this design formula can be used to quickly design the coupler in the two-stage RTWT.Then,some new 0dB and 3d B branch-guide couplers are proposed and designed. |
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