Key Technology And Experimental Research On High Efficiency Of High Performance Traveling Wave Tube

Traveling wave tubes(TWTs)have been widely used in satellite communication,data transmission,electronic countermeasures,deep space exploration,and various other domains,for their high power,high efficiency,long life and broad bandwidth.The overall efficiency serves as a crucial metric in evaluating TWTs performance,garnering increasing attention from researchers for the advancement of high efficiency TWTs.Progress in high efficiency technology stands to significantly enhance TWTs performance in China,offering pivotal support for the evolution of satellite systems and the next generation of weaponry and equipment.In this dissertation,the fundamental theory and pivotal technology about high efficiency TWTs are studied.A fast design approach for the beam-wave interaction circuit is proposed,and a multi-objective optimization design tool for interaction circuit is developed.Additionally,the detection technology of electron beam is studied,which can realize the electron beam by using the experimental method.These key technologies lay a solid technical foundation for the advancement of high efficiency TWTs,as outlined below:1.A fast design method for the beam-wave interaction circuit is proposed based on the three-dimensional nonlinear beam-wave interaction theory of TWTs and the concept of field relative phase,which synthesizes a wealth of engineering experience.The design method only relies on the field relative phase,which can guide the design of high efficiency TWTs.The interaction circuit of a C-band helix TWT is designed by using this method,the output power and electronic efficiency are improved.2.An optimization design tool is developed by combining the nondominated sorting genetic algorithm II(NSGA-II)and the three-dimensional nonlinear beam-wave interaction theory.The tool can optimize the electronic efficiency and recovery efficiency at the same time,which can improve the overall efficiency of TWTs.Besides,the tool can also realize multi-objective optimization of various indicators,encompassing output power,gain,phase distortion,AM/PM and more.It can solve the problem that the traditional massive scanning simulations is time-consuming and difficult to find the optimal solution in the design of interaction circuit.The interaction circuit of an L-band high efficiency TWT is optimized by using this tool,and a design scheme with better performance is obtained.3.The global multi-objective optimization design tool of TWTs is formed by combined the optimization design tool for interaction circuit with the optimization design tool for electron optics system,which can achieve the optimization design of whole tube.After decomposing the indicators of a 200 W Ku-band helix TWT,the interaction circuit,electron gun and collector are optimized by using the tool.The design schemes of 150 W Ku-band space TWT is used as the initial design schemes.By employing the global optimization design tool,the whole design processes consumed 49 hours.Compared with the multi-week design time required for large-scale scanning simulations,the global multi-objective optimization design tool can effectively shorten the design time.4.A detection and analysis system of electron beam is developed,which can detect the state of the electron beam emitted by the electron gun.The system structure,synchronous control,measurement method and data analysis are designed.Based on the single-pulse test method,the system can use Faraday cup to measure the current density distribution and trajectory envelope of the electron beam,which is of great significance to strengthen the control of electron beam and improve the beam transmission.A Ku-band electron gun is tested by this system.The current density distribution,waist radius and waist position of electron beam without the magnetic field are obtained.5.Based on the optimized design scheme and tested results,a prototype of the 200 W Ku-band helix TWT with the four-stage depressed collector is fabricated.The hot test shows that the prototype is capable of providing over 200 W output power and over 54 d B gain within a 1GHz bandwidth at Ku-band.The overall efficiency is greater than 69%,when the phase distortion and AM/PM are controlled within 49 deg and 3.8deg/d B,respectively.Besides,the performance of the newly laboratory prototype has an overall efficiency of more than 72% over the operating band,the whole performance has successfully reached the international advanced level.