The Study Of Photocathode Electron Gun For An Ultrafast Electron Microscope

With the exploration and development of the microcosmic world,electron microscope has a wide range of applications in the fields of biology,chemistry and materials.In order to explore the structure of matter and its dynamic process at a smaller microscopic scale,the development of ultrafast electron microscopes(UEM)with high spatial and temporal resolution.In order to fit these requirements,a photocathode microwave electron gun was chosen as electron source of UEM.By improving the acceleration gradient of the electron gun,the electron beam has higher energy,which increases the spatial resolution.By using lasers with ultra-short beam,the resulting electron beam length will be greatly reduced,which increases the time resolution.At present,many institutions have begun to design.In summary,this paper is of great significance to the study of ultrafast electron microscopes.In this paper,first the electron gun of the ultrafast electron microscope is designed,which operating frequency of the electron gun is C-band 5712MHz,and using coaxial coupling structure to feed power.The thesis is divided into three parts.The first part is the physical design.The accelerating cavity and the coupler of the electron gun are designed and simulated,and obtained the structure with high quality factor and shunt impedance.By means of simulation optimized,the coupling structure can be to reduce the reflection loss of microwave feed.The second part is the beam dynamics simulation.The beam dynamic parameters of the electron gun during the process and at the downstream are obtained,and make it to achieve the design goal.The third part,includes the manufactures and the preparation for the coming experiments,which has prepared the perturbators of different diameters and obtain the shape by test way.The perturbators are used for the subsequent measurement of the distribution of the electric field along the axis of the electronic gun.The work and experimental content of this study provide the data base of analog calculation for the overall development of the next ultrafast electron microscope.