超环面晶体成像技术分析及实现

Analysis and Implementation of Toroidally Bent Crystal for X-ray Imaging Technology

为了在聚爆装置上对目标靶进行光谱分析及成像诊断,设计了超环面晶体X射线成像系统。从理论上分析了Johann型弯曲晶体结构的成像像差,利用模拟软件对基于布拉格结构的弯晶系统进行仿真成像,研究布拉格角与成像空间分辨力的关系。采用Oxford射线管、X射线检测器及云母超环面晶体对金属网格进行了X射线背光成像实验,实验获得了网格的X射线图像及铜的Kα射线光谱,结果表明超环面晶体能够进行微米级的高分辩成像,也可用于检测X射线光谱。

A toroidally bent crystal X-ray imaging system was designed in order to detect the X-ray spectrum and diagnose the image of target on fusion device. The Johann point-focusing geometry aberration was calculated in theory. Ray-tracing simulations of an optical X-ray system based on the bent crystal working operating in Bragg conguration for monochromatic projection imaging of grid samples are presented, and the relation between the Bragg angle and the spatial resolution of the imaging system is investigated. The X-ray radiation from a small source is dispersed by a transmission grid placed in front of the toroidal crystal imager. Our successful applications suggest that the bent crystals may be used to image with high spatial resolution. This configuration retains the advantages of the bent mica crystal spectrograph while enabling the analysis of the spectral radiation. Spectrally and spatially resolved Ks spectra of Cu were observed.