基于晶体布拉格反射镜的X射线谐振腔光学设计

Optical Design of X-Ray Resonant Cavity Based on Crystal Bragg Mirrors

设计了一个以蓝宝石晶体作为布拉格反射镜构成的谐振腔系统,控制X光脉冲辐射束的状态以实现其在一个开放腔中的稳定传输,进而形成振荡。以两块平面晶体布拉格反射镜构成的开放稳定腔系统为模型,通过计算其传输矩阵和分析辐射束横向稳定性条件,得到了谐振腔中两块透镜的焦距和间距的关系。优化该谐振腔系统设计参数使之满足增益最大化条件,即辐射束瑞利长度Z_(R)与电子束聚焦参数Z_(β)匹配。使用X射线追迹软件SHADOW进行光学追迹模拟。模拟结果显示,辐射束在整个谐振腔系统中传输的单程损耗小于20%,在谐振腔中振荡一个周期后的状态与初始状态虽然有所差异但仍可接受。模拟结果表明了该谐振腔系统光学设计参数的可行性。

A resonant cavity system composed of a sapphire crystal as a Bragg mirror is designed to control the state of the X-ray pulse radiation beam to achieve stable propagation in an open cavity,and then form oscillation.Taking the open stable cavity system composed of two plane crystal Bragg mirrors as the model,the relationship between the focal length and the distance between the two lenses in the resonant cavity is obtained by calculating the transport matrix and analyzing the lateral stability condition of the radiation beam.The design parameters of the resonant cavity system are optimized to satisfy the gain maximization condition,i.e.,the Rayleigh length Z_(R)of the radiation beam matches the focusing parameter Z_(β)of the electron beam.The X-ray tracing software SHADOW is used to simulate the optical tracing.The simulation results show that the single-pass loss of the radiation beam in the entire resonant cavity system is less than 20%.Although different from the initial state,the state of the radiation beam after oscillating for one period in the resonant cavity is acceptable.The simulation results show that the optical design parameters of the resonant cavity system are feasible.