| At present,millimeter-wave and microwave vacuum electronic devices(VEDs)play a crucial role in the development of remote sensing satellites,vehicle-mounted radar,missile seeker and security.As the requirements of high power,high gain and miniaturization further improved,the only way to further enhance the power of VEDs is to increase the voltage and current.However,there are some negative problems,such as high-frequency breakdown,and the design difficulty of power supply system will increase significantly.Therefore,it is thought to develop an electronic optical system that can achieve high performance under low operating voltage.After considering the device requirements,focusing difficulty,and existing design methods,the multiple-beam electron gun was selected for research.This thesis introduces the design,simulation and optimization method of a compact 5-beam electron gun,which is capable of serving Ka-band Multiple-beam Extended Interaction Oscillator(MBEIO).In this study,the voltage and current of the electron gun were preliminarily determined according to the requirements of device parameters.Then,by using the commercial 3-dimensional simulation software(CST),the multiple-beam electron gun and solenoid magnetic circuit focusing system were designed on the basis of basic parameters.Main work and innovation for this dissertation are as followed:1.The single-beam Pierce electron gun without external magnetic field was primarily designed.According to the requirements of the device,the reasonable anode accelerating voltage and cathode emission current of the electron gun were calculated theoretically.Furthermore,the parameters of the geometric structure of the electron gun were determined and optimized by using CST simulation software,such as the distance between the anode and the cathode,the half-cone angle of the cathode,and the shape of the focusing electrode.2.The solenoid magnetic circuit system was simulated and researched.The application of solenoid magnetic circuit system generated a focusing magnetic field.The magnetic field offset the space charge force between the electrons and compressed the electron beam entering the beam tunnel.According to the anode beam tunnel and other parameters of the single-beam electron gun,the magnitude of the focusing magnetic field was determined by the simulation.Finally,the solenoid magnetic circuit system was designed.3.The 5-beam electron gun with focusing magnetic field was designed and simulated.The problem of magnetic wall saturation of solenoid magnetic circuit system in electron gun area and the interaction between off-axis radial magnetic field and offaxis distance were analyzed emphatically.These analyses were intended to minimize the angular rotation of the electron beam and the beam bombardment on the tunnel wall.The design of the 5-beam electron gun was verified and optimized by using CST simulation software.The effect of the focusing magnetic field on the electron beam was simulated to ensure the rigidity,laminar flow and transparency of the electron beam.Finally,in the beam tunnel,the filling ratio of each electron beam was 60%.4.On the basis of simulation optimization,the processing and experiment of solenoid magnetic circuit system were completed,which laid a solid foundation for the design of magnetic circuit system in the future.In this thesis,a high performance 5-beam electron gun equipped with solenoid magnetic circuit system has been designed,which provides an effective and feasible method for the study of multiple-beam electron gun.This kind of electron gun is completely suitable to apply to lower operating voltage,lower noise and wider bandwidth VEDs.The operating voltage of the electron gun is 19 kV,and the total beam current is 6 A.The simulation results show that the performance of the electron gun has reached the design purpose. |
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