群聚电子FEL辐射机理研究

在应用需求驱动下，自由电子激光正朝着更完善的性能，如高相干性，高亮度，高重复频率，高稳定性，更灵活，更紧凑的装置的方向深入发展。使用预群聚的电子束对高增益FEL和低增益FEL都有重要的意义。自由电子激光的基本物理思想就是使电子群聚，不同的电子同相位，从而产生的辐射相干加强。在本项目中我们将在国外已有工作及我们自己工作基础上，对群聚电子FEL辐射机理开展深入研究，研究预群聚电子束及超短单束团的FEL辐射特性，研究其中光的衍射，脉冲滑移及波导等各种物理效应，阐明物理机制，给出影响关系；给出低增益与高增益情况下，预群聚电子束及超短单束团辐射光场的发展及饱和的理论描述；还对预群聚电子束及超短单束团的产生方案进行研究，研究电子束的群聚因子和品质参数，如发射度，能散的影响关系及其演化。研究工作将为发展与优化全相干，小型化的X-FEL以及紧凑型THz-FEL光源提供理论支撑。

Spurred by the application requirements, free electron lasers are developing in-depth toward the direction of better performance, such as high coherence, high brightness, high repetition rate, high stability, more flexibility and more compact. The basic physic idea of free electron laser is the electron bunching, different electrons with same phase to produce coherent radiation. Using pre-bunched electron beam has important significance for both high gain FEL and low gain FEL. In this project, on the bases of the related works abroad and our own, we will study the radiation mechanism of bunched electron in-depth: study FEL radiation characteristics of pre-bunched electron beam and of ultrashort single bunch electron; study the physic effects such as the diffraction, pulse slipping and waveguide; we will elucidate the physic mechanism inside, give the impact relations, give a theoretical description of the radiation field development and saturation for pre-bunched electron beam and ultrashort single bunch electron in both the low gain and high gain case. We will also study generation schemes of pre-bunched electron beam and of ultrashort single bunch electron; study impact relations and evolution of the electron beam bunching factor and quality parameters, such as emittance, energy spread. The research work will provide a theoretical support for the development and optimization of fully coherent, compact X-FEL and compact THz-FEL light source.