激光等离子体加速的自由电子激光理论与关键技术研究

As the 4th generation light sources, free-electron lasers (FELs) based on the conventional radio-frequency accelerator could provide advanced hard X-ray radiation with ultra-high brightness, ultra-short pulse length and full coherence. FELs open up a new perspective for the development of the recent science areas, having been focused and promoted widely by the international community. In terms of cost, scale and users’ requirement, the development trends of accelerators and FELs are small-scale and table-top. As a new accelerator, laser plasma accelerator (LPA) can generate high energy electron beams within an ultrashort distance, which holds great promise to realize a compact FEL. However, limited by the LPA beam quality, it has not realized the lasing of the LPA based FEL around the world. Here the application project propose to study the mechanisms of generation of the LPA based FELs through the theoretical analysis and numerical simulation. The main study contents of the project include beam dynamical manipulation of the LPA beam, proposal of the new LPA-FEL mechanisms, promotion of the existing LPA-FEL mechanisms, development of the numerical model and simulation code, and analysis the effects of the LPA beam jitter. It is expected that the project would lay the foundation for the compact X-ray light source, be an important reference for the construction of the national LPA based FEL facilities and a great push significance for the development of the 5th generation light sources in the future.

基于射频加速技术的自由电子激光（FEL）作为国际公认的“第四代光源”能够提供超高亮度、超短脉冲、全相干的X射线，为多种科学领域开辟了全新的道路，受到了国际上广泛关注和大力推动。从成本、规模和用户需求来讲，加速器和FEL在朝向小型化、台式化的方向发展。近年来，基于激光等离子体加速技术（LPA）产生电子束的方式成为了一个热门的研究方向。但受制于LPA电子束品质问题，当今世界还未能实现LPA-FEL出光。本项目将结合LPA和FEL物理前沿，通过理论研究和数值模拟，对实现LPA-FEL展开全面探索。我们将对LPA电子束进行相空间操纵，提出LPA-FEL新的运行机制，深入发展现有的LPA-FEL运行机制，开发相应的数值模型和模拟软件，掌握LPA-FEL出光的关键技术。本项目为实现紧凑型X射线光源奠定基础，为国家的LPA-FEL装置建设提供参考，为未来“第五代光源”的发展提供重要推动作用。

激光等离子体加速器（LPA）由于其超高的加速梯度，可以实现台式化的自由电子激光（FEL），极大地降低装置规模和花费，是下一代先进光源的重要发展方向。我国科研人员于国际上率先完成了LPA驱动FEL的实验验证，为实现台式化FEL装置奠定了重要基础，但受到该电子束品质的限制，包括大初始发散角、大能散和剧烈的抖动性等问题，FEL的实现难度尤其是朝向短波长、FEL性能多样化等方向具有巨大的挑战。项目负责人从理论研究和数值模拟上，对LPA实现FEL开展了深入的探索研究，并首创性地提出了LPA束流切片操纵技术实现双色X射线FEL的物理新机制。理论研究为LPA实现FEL以及性能多样化提供了重要发展方向，同时正在准备开展实验验证，为新一代先进光源的实用化和未来用户实验奠定重要基础，助推我国在该研究领域走在世界最前列，具有重要的科学研究意义。