基于皮秒拍瓦激光产生的高能X射线源具有强度高、脉宽短、焦点小的特点,利用这种X射线源发展出来的高时空分辨率X射线点投影背光照相是强加载条件下材料动态响应,以及惯性约束聚变等高能量密度物理研究中亟需的重要诊断技术。目前,研究人员主要依靠TITAN、OMEGA-EP和神光Ⅱ升级等大型皮秒拍瓦激光装置,对皮秒拍瓦激光与固体靶相互作用产生的X射线的能谱、转换效率、分辨率等关键参数进行了研究,发展了点投影背光照相技术,并开展了动态演示实验,成功获得了惯性约束聚变内爆过程和冲击加载材料微喷过程的演示图像。

X-rays produced through picosecond petawatt lasers have high flux, short pulse duration, and tiny focal spot. High spatial and temporal resolution X-ray point-projection backlight radiography developed using such high flux X-rays is an important diagnostic technique for measuring the dynamic response of materials under intense laser load, the inertial confinement fusion, and other high energy density physics. Short pulse X-rays are generated through the picosecond petawatt laser beams on TITAN and OMEGA-EP systems, as well as the upgraded SHENGUANG-II facility and other large picosecond watt laser facilities. The spectrum, conversion efficiency, and resolution of the X-ray backlights produced using the interactions between the picosecond petawatt lasers and solid targets are characterized in the experiments conducted herein. Furthermore, the technology of point projection backlighting is developed, and the dynamic demonstration experiment is performed. Images of the compressed fuel of inertial confinement fusion targets and the ejecta of shock-loaded materials are successfully obtained using backlight radiography.