高时间分辨X射线辐射流诊断技术研究

X-ray power diagnosis with high temporal resolution is very important in the field of indirect drive fusion research. But with the development of the fusion research, X-ray power diagnosis with picosecond level temporal resolution are needed,the traditional diagnostic facilities are not suitable for this requirement. The only one X-ray diagnostic instrument with picosecond level temporal resolution is X-ray streak camera.But it can not be used as a power diagnosis directly due to the complexity of energy spectrum response of the photocathode. So this research project is aimed at developing a radiation flow diagnostic device with 10ps temporal resolution by making the X-ray streak camera can be used as a power diagnosis directly. A transmission-flat response X-ray photocathode between the energy spectrum from 100eV-4000eV will be designed and manufactured and be coupled to the streak camera to achieve this aim. Once this device is developed successfully, the details change of the radiation flow can be observed by it, the scientist can understand the coupling process of laser and hohlraum more deeply and get more physical information of the hohlraum. The information can be used to guide the size optimization of the hohlraum and the laser pulse shaping and be used to guide the simulations of laser-plasma interaction and capsule implosion process..

高时间分辨辐射流诊断技术在激光间接驱动聚变研究中有着十分重要的作用，随着激光聚变研究的深入，当前诊断设备在时间分辨力上无法满足需求，新型高时间分辨辐射流诊断技术正成为重要研究的方向。X射线条纹相机是当前唯一具有10皮秒及以上时间分辨的X射线探测器，但其阴极对X射线具有复杂的能量响应使其无法直接用于对辐射流的定量诊断中。本项目拟利用一定结构的滤片和阴极对X射线具有互补的响应特性而发展一种在能区100eV-4000eV范围内具有平响应特性的透射式光阴极并将其耦合到现有条纹相机上，使得X光条纹相机能够用于对辐射流的诊断，从而发展一种高时间分辨的辐射流诊断技术。利用该技术可更细致观察辐射场的变化过程，从而更充分了解激光腔靶耦合物理过程，这对促进腔靶的优化设计和激光脉冲整形以及校验模拟程序都具有十分重要的作用，最终可促进我国激光惯性聚变事业的发展。

本课题通过实现对X射线条纹相机光阴极的平响应化，发展了一种可更细致观察聚变实验中辐射场快速变化的高时间分辨辐射流诊断技术。采用理论计算的方法完成了透射式平响应光阴极的设计并对其性能进行了初步研究，采用微纳加工工艺完成了光阴极的制作，获得了高质量的阴极样品，同时设计了平响应阴极与条纹相机的耦合结构，实现了阴极与条纹相机的耦合。在同步辐射光源上对阴极样品进行了标定，结果表明平响应光阴极的不平整度小于10%，与理论设计吻合较好。还对X光条纹相机的整体标定方法进行了初步研究，促进了对X光条纹相机整体响应性能的进一步认识。在神光III原型装置对该辐射流诊断技术进行了初步实验应用，并与传统辐射流诊断技术进行了比较，结果表明了本项目辐射流诊断技术的有效性，时间分辨优于25ps。在采用更高时间分辨的X光条纹相机情况下，时间分辨可优于10ps。