基于束流相空间拍频产生锁模自由电子激光的物理机制研究

Research on physical mechanism of mode-locked free-electron laser based onelectron beam phase space beating

提出基于束流相空间拍频产生锁模多色自由电子激光的方案,利用带有能量啁啾的电子束流和上海软X射线自由电子激光装置(SXFEL)上的两个调制段-色散段结构,在束流中通过拍频形成多个流强脉冲串,并在此基础上进行高次谐波辐射,产生锁模多色自由电子激光辐射脉冲。模拟结果表明,利用264 nm的种子激光,可在束流中形成18次谐波的群聚分量,并能最终产生中心波长约14.58 nm的锁模多色FEL辐射。

The theory,method,and experimental studies on mode-locked free-electron laser(FEL)have been ofgreat interests in the world.In this paper,we propose a method to generate mode-locked multi-color free-electron laserradiation pulses based on the electron beam phase space beating.Utilizing an electron beam with head-tail energychirp and the two modulator-chicane setups in the Shanghai Soft X-ray free-electron laser facility(SXFEL),multiplecurrent pulse trains can be formed and mode-locked multi-color free electron laser pulses can be generated.Thesimulation results indicate that,with the help the 264 nm seed laser,bunching factor at the 18th harmonic of the seedlaser can be formed and ultimately mode-locked multi-color FEL radiation pulse with a central wavelength ofapproximately 14.58 nm can be generated.This study is of great significance for the development of the mode-lockedFEL in China and the performance improvement of the SXFEL facility.