高能康普顿伽玛光源理论模拟与关键技术研究

Being a type of important tools, various light sources have major and critical contributions in the achievement of modern science and technology. Among these light sources, lasers, including free-electron lasers, have been providing optical beams, ranging from far-infrared to x-ray region, for researches in various areas. The light source based upon Compton scattering using high energy electron and laser beams is currently the only method used to produce high intense, highly aligned, pseudo-monochromatic and highly polarized optical beams in gamma-ray region. An effective and useful Compton light source should be capable of producing high enough flux of photon beam, and also providing means to manipulate the out-going photon beam. This proposal will focus on the researches of the technologies used to increase the flux and manipulate some physical properties of the scattered gamma-ray beam. The total flux of the scattered gamma-ray beam is mainly determined by the total number of the incident photons and electrons participating in the collision, and the matching of their distribution functions. Researches on increase the number of the incident photons and optimization of the matching of the distribution functions of the incident electron and photon beams are proposed in this application. In order to increase the number of the photons, we will perform researches on acquiring a high power energy storage cavity for laser beams. In the meanwhile, the matching of distribution functions of the incident electron and photon beams will also be studied using simulations to optimize the collision. On the other hand, researches on manipulating the energy and pulse length of the scattered gamma-ray beam will also be performed using simulations. The impact of large scale collision angle changes on energy, energy spread, flux and pulse length of the scattered gamma-ray beam will be studied for developing above manipulation methods. The method used to slightly change the propagation direction of the scattered gamma-ray beam will also be studied. This method can be used for aiming and scanning the gamma-ray beam on experiment samples, which is very essential and critical for various experiments.

光作为探测工具和信息载体，在科学研究和工业应用中发挥着重要作用。为了获得各种波长的优质光束，人们发明了许多种重要光源。其中激光和同步辐射光源可以提供从远红外到X射线的光束。更短波长的优质伽玛光束现阶段只有利用高能电子和激光束之间的康普顿散射来产生。一个高效且实用的伽玛光源应能提供足够高的伽玛光通量和一定的光束操控手段。本项目的研究将集中在用以提高伽玛光通量和伽玛光束操控技术上。伽玛光通量主要决定于参与碰撞的电子数和光子数以及它们的分布函数，本项目通过研究高功率激光储能腔技术，为通过提高激光束功率来增加光源光通量奠定基础。同时通过数值模拟来研究电子束与光子束分布函数的匹配关系来提高通量。另外，通过研究大范围改变碰撞角对散射光束能量、能散、通量以及脉冲长度等物理特性的影响，来获得对散射光束能量和脉冲长度的操控技术；研究在小范围内改变伽玛光束传播方向的技术，来实现伽玛光束对实验样品的瞄准和扫描。

提高康普顿光源亮度的一个重要途径是提升参与碰撞的激光功率。本课题针对提高激光功率开展了激光功率增强腔的关键技术研究。包括研发了基于PDH技术的锁腔技术，并在微波谐振环和激光谐振腔上进行了验证，效果良好。基于Nd:YVO4增益晶体和半导体可饱和吸收镜（SESAM）的固态激光器搭建了锁模激光器，在880nm、泵浦功率30W时，输出功率6W,重复频率162.5MHz,输出光斑质量M^2接近1。设计了便于固态激光光腔的准直激光装置，提高了固态激光器的调节效率，并将设计的结构申请了实用新型专利。研究并进而设计和搭建了基于双腔镜的激光功率增强腔样机，该增强腔腔长1845mm,腔镜反射率R=99%，模拟得到腔精细度为312.58。同时，针对提高束流品质的需求，开展了基于多目标遗传算法的束流参数优化方法的研究，以及储存环束流工作点在线反馈技术的研究。另外，还研究了双谐振拓扑高压脉冲电容器充电电源脉，该冲功率技术可广泛应用于激光聚变、离子束、微波功率源、雷达发射机等领域。以上各项研究均取得了预期目标