Simulation And Design Of High Precision Grid Control Electron Gun

In the 1940s,due to increased demand in radar,communications,electronic countermeasures,etc.,a very important category of microwave electric vacuum devices-traveling wave tubes(TWT)came out.As an electronic vacuum device that can generate or amplify microwave signals,the working principle of the traveling wave tube is to use the interaction between the electron beam and the microwave signal to achieve energy exchange,and ultimately achieve the purpose of generating or amplifying the signal.As an important part of it,the main function of the electron optical system is to generate,gather,transmit,and collect electron beams.It can be said that the quality of the electronic optical system has a direct impact on whether the expected effect of the microwave electric vacuum device can be realized.With the development in recent decades,the traditional Pierce electron gun has been difficult to meet the new requirements of high power,long distance,fast response,and light weight for traveling wave tubes in the military and aerospace fields.Its huge pulse energy severely limits the mobility and range of the traveling wave tube,and the emergence and application of the grid-controlled electron gun achieves the purpose of using a smaller pulse energy to control the working state of the traveling wave tube,which has been widely studied and applied.However,due to the complexity of its structure,until now,the structural design and optimization of the grid-controlled electron gun and the matching focus magnetic field design are still difficult points in production and processing.This paper mainly studies the simulation and design methods of the grid-controlled electron gun and the focusing magnetic field.The main contents are as follows:(1)analyzes and studies the structural design of the grid-controlled electron gun.It is mainly divided into the influence of two structure types,non-grid structure and grid structure,on the performance of the grid-controlled electron gun.First,analyze the influence of the non-grid structure on the performance of the grid-controlled electron gun,such as the cathode radius,the focus radius,the focus length,and the distance between the cathode and anode.Secondly,analyze the influence of grid structure on performance such as grid thickness,number of horizontal wires,grid curvature and position.(2)According to the iterative synthesis method and the design steps that have been used in production,that is,the method of adding a grid to the model of the gridless gun,designs the corresponding structure.According to the regular conclusions obtained by analyzing the impact of structural changes on performance,uses the EOS module in the MTSS software to continuously adjust and optimize,and obtains a grid-controlled electron gun structure that meets the requirements of the index.(3)designs the corresponding magnetic field of the designed grid-controlled electron gun,and in the design process,in view of the inconsistency of the simulation results caused by the magnetic leakage problem,propose a design method of magnetic field which can optimize electron injection molding and reduce the influence of the magnetic leakage problem to the electron gun.(4)introduces the coupling design method of the grid-controlled electron gun and the periodic permanent magnet focusing system.By introducing the basis of coupling design method,coupling theory and tunnel divergence,the author proposes the design idea of improving the laminar fluidity at the cost of the electron beam radius,facilitating the design of the focus magnetic field,and finally feedbacking the improvement of the electron beam shape.And optimized the designed grid-controlled electron gun structure and matching focusing magnetic field,and obtained good results.Aiming at the design difficulties of the grid-controlled electron gun,this article summarizes the influence of the structural parameters,and designs the focused magnetic field of the designed grid-controlled gun structure,providing the coupling optimization idea of the grid-controlled gun structure and the focusing magnetic field,which has reference value for the design of the grid-controlled gun structure.