Design of S-band photoinjector with high bunch charge and low emittance based on multi-objective genetic algorithm  

作　　者：Ze-Yi Dai Yuan-Cun Nie Zi Hui Lan-Xin Liu Zi-Shuo Liu Jian-Hua Zhong Jia-Bao Guan Ji-Ke Wang Yuan Chen Ye Zou Hao-Hu Li Jian-Hua He 

机构地区：[1]The Institute for Advanced Studies,Wuhan University,Wuhan 430072,China

出　　处：《Nuclear Science and Techniques》2023年第3期93-105,共13页核技术（英文）

基　　金：supported by the Science and Technology Major Project of Hubei Province,China (No.2021AFB001).

摘　　要：High-brightness electron beams are required to drive LINAC-based free-electron lasers(FELs)and storage-ring-based synchrotron radiation light sources.The bunch charge and RMS bunch length at the exit of the LINAC play a crucial role in the peak current;the minimum transverse emittance is mainly determined by the injector of the LINAC.Thus,a photoin-jector with a high bunch charge and low emittance that can simultaneously provide high-quality beams for 4th generation synchrotron radiation sources and FELs is desirable.The design of a 1.6-cell S-band 2998-MHz RF gun and beam dynamics optimization of a relevant beamline are presented in this paper.Beam dynamics simulations were performed by combining ASTRA and the multi-objective genetic algorithm NSGA II.The effects of the laser pulse shape,half-cell length of the RF gun,and RF parameters on the output beam quality were analyzed and compared.The normalized transverse emittance was optimized to be as low as 0.65 and 0.92 mm·mrad when the bunch charge was as high as 1 and 2 nC,respectively.Finally,the beam stability properties of the photoinjector,considering misalignment and RF jitter,were simulated and analyzed.

关 键 词：Electron linear accelerator PHOTOINJECTOR Beam dynamics Multi-objective genetic algorithm 

分 类 号：TL53[核科学技术—核技术及应用] TP18[自动化与计算机技术—控制理论与控制工程]