Study On Design Of An Electron Linear Accelerator With High Capture Efficiency

The electron linear accelerator has shown great application value in the field of medicine,agriculture and industry.The electron gun and the accelerating tube are very critical parts in an electron linear accelerator,the beam from the electron gun will be accelerated in accelerating tube,and the capture efficiency have a significant impact on the output power.The motion of electron beam in a thermionic gun and accelerating tube is researched in this paper.And a physics design of an electron linear accelerator with high capture efficiency has been finished.Besides the energy spread is good and has certain value in industrial irradiation.In order to satisfy the requirement of accelerating structure about beam parameters,a conceptual design of a 45 keV thermionic direct-current electron gun has been achieved based on the classical Pierce gun model.The simulation results show that the electron gun has a good focusing effect and laminarity.According to the beam dynamics,an accelerating structure with a variable phase velocity and field strength has been proposed in the design of accelerating structure.MATLAB codes for beam dynamics calculation in an accelerating tube have been developed.The feasibility of the accelerating structure with high capture efficiency has been verified.And the distribution of phase velocity and electric field strength along the accelerating structure has been initially completed.Then on the foundation of the results of beam dynamics,the design of transverse focusing system has been obtained.The cavities of the accelerating tube have been designed by means of some simulation software for high frequency electromagnetic field.And the accelerating tube design has been successfully examined by PARMELA,which is a software for beam simulation.Beam dynamics simulation is in good agreement with the calculation results,so it proves that the design of accelerating tube is workable.Finally,the cooling parameters of solenoids has been calculated to meet the practical needs of engineering.