菲涅耳波带板应用于聚变靶的高分辨X射线成像分析

Analysis of high-resolution X-ray imaging of an inertial-confinement-fusion target by using a Fresnel zone plate

在惯性约束核聚变研究中,为了实现1μm高空间分辨keV-X射线成像,文中发展了菲涅耳波带板(FZP)直接成像的分析方法,并通过数值计算研究了FZP的成像特性.针对钛Kα线(光子能量4.51keV,波长0.275nm),提出了FZP参数,对制作技术的要求较低.研究了靶尺度的影响.FZP的有效视场使它能够对数毫米大尺度靶实现高分辨成像.还研究了入射光的光谱带宽对成像的影响.FZP的色差有助于单色成像,但是带宽超过限度会导致像的反衬度降低.这些结果表明FZP应用于聚变点火靶的高空间分辨X射线成像的能力,也为应用提出了要求.

Aiming at 1 μm high resolution in imaging an inertial confinement fusion （ ICF） target,a method is developed for analyzing the direct imaging by a Fresnel zone plate （FZP）,and numerical calculations are carried out to study the FZP imaging characteristics in the keV X-ray range. For the Ti Kα line （photon energy 4. 51 keV,wavelength 0. 275 nm）,the FZP parameters are suggested,for which the technical requirement of fabricating the outmost zone is relatively low. The influence of the target size on the imaging is studied for the first time. It is shown that the FZP has a large effective field of view and the image quality can be guaranteed even for a target of several millimeters. The influence of the spectral bandwidth of a polychromatic incident light on the imaging is also studied. Monochromatic imaging can be obtained due to the achromatic property of the FZP. However,if the bandwidth is larger than a certain limit,the image contrast will be degraded. These results indicate the feasibility of applying an FZP in high-resolution X-ray imaging of an ICF ignition target and put forward the requirements as well.