Theory And Experimant On Low Emmitance Photocathode Electron Radio Frequency Gun

Generation of high quality electron beams is a critical issue in the success offree-electron laser (FEL)facilities. The characteristics of electron beams and reliabilityof a FEL facility strongly depend on properties of the electron source. Compared withother electron sources, the photocathode RF guns have very high accelerating gradiantwhich could provid high quality electron beams. In order to get electron beam withsufficient brightness, the photocathode RF guns are widely adopted in most of FELfacilities and time-resolved micrscopis in recent days.The photocathode RF gun present in this thesis belongs to the BNL/KEK/SHItype photocathode RF gun. The structure is optimized to eliminate the detrimentalmodes which imported by asymmetric structures. Micorwave parameters areoptimized, such as Q quality and coupling factor. The design and the cold testexperiments of the RF gun is presented in this thesis comprehensive. A lot of tunningexperiments and field distribution study are carried out.Intensive simulations have been carried out to study the two frequency RF gun.2D design of a two-frequency RF gun working at2998MHz and8994MHz ispresented. Beam dynamics of the two-frequency RF gun is carried out for high chargebeam. The results show the advantage of a two-frequcny RF gun over a standardsingle-frequency RF gun for improving the beam quality for high charge beam. Theprocess of bunch compression with a two-frequency gun is performed. As acomprasion, the case with a single-frequency gun is performed also.