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TY - UNPB AU - Li, C.L. AU - Feng, L. AU - Liu, B. AU - Wang, X.T. AU - Zhang, W.Y. ED - Tavares, Daniel ED - Picoreti, Renan ED - Bruno, Gustavo ED - Marques, Sergio ED - Schaa, Volker R.W. TI - Photoinjector Driver Laser Temporal Shaping and Diagnostics for Shanghai Soft X-ray Free Electron Laser J2 - Proc. of IBIC2020, Santos, Brazil, 14-18 September 2020 CY - Santos, Brazil T2 - International Beam Instrumentation Conference T3 - 9 LA - english AB - It is known that the intensity distribution plays an important role in the electron bunch character, such as its transverse emittance, longitudinal structure. Compared with longitudinal Gaussian distribution, Driver laser pulse with longitudinal flattop structure can produce electron bunch with lower emittance. This paper presents electron beam structure and emittance under different driver laser structure, specifically, laser pulse temporal shaping method for producing Gaussian beam and flattop beam are presented. The advantage and disadvantage of the two method are also discussed. Flattop beam produced from BBO stacking is more benefit for producing electron beam with lower emittance, but significantly increase the microbunch effect. However, Gaussian beam has the advantage to help reducing the mircobunch effect. Moreover, cross correlation method for characterization the laser pulse temporal structure are also presented, particularly, the group velocity mismatch effect induced by the sum frequency BBO crystal are discussed. PB - JACoW Publishing CP - Geneva, Switzerland ER -