摘要
Besides the original seeded undulator line,in the soft X-ray free-electron laser(SXFEL) user facility in Shanghai,a second undulator line based on self-amplified spontaneous emission is proposed to achieve 2-nm laser pulse with extremely high brightness.In this paper,the beam energy deviation induced by the undulator wakefields is numerically calculated,and 3D and 2D results agree well with each other.The beam energy loss along the undulator degrades the expected FEL output performances,i.e.,the pulse energy,radiation power and spectrum,which can be compensated with a proper taper in the undulator.Using the planned time-resolved diagnostic,a novel experiment is proposed to measure the SXFEL longitudinal wakefields.
Besides the original seeded undulator line,in the soft X-ray free-electron laser（SXFEL） user facility in Shanghai,a second undulator line based on self-amplified spontaneous emission is proposed to achieve 2-nm laser pulse with extremely high brightness.In this paper,the beam energy deviation induced by the undulator wakefields is numerically calculated,and 3D and 2D results agree well with each other.The beam energy loss along the undulator degrades the expected FEL output performances,i.e.,the pulse energy,radiation power and spectrum,which can be compensated with a proper taper in the undulator.Using the planned time-resolved diagnostic,a novel experiment is proposed to measure the SXFEL longitudinal wakefields.
基金
supported by the National Natural Science Foundation of China(Nos.11475250 and 11322550)
Ten Thousand Talent Program
