微靶型X射线管不同靶材出射光斑对比研究  

A comparative study on the focus size of different target materials of micro target X-ray source

作　　者：左卓 何兴 张松 颜瑜成 覃骏 ZUO Zhuo;HE Xing;ZHANG Song;YAN Yucheng;QIN Jun(Chengdu University of Technology College of Engineering Technology,Leshan 614000,China;Southwest Institute of Physics,Chengdu 610225,China)

机构地区：[1]成都理工大学工程技术学院,乐山614000 [2]核工业西南物理研究院,成都610225

出　　处：《核技术》2020年第10期29-33,共5页Nuclear Techniques

基　　金：乐山市科技局项目(No.19SZD117);成都理工大学青年科学基金(No.C122018033)资助。

摘　　要：针对半球、锥体、圆柱三种微形结构靶X射线管,利用蒙特卡罗(Monte Carlo)方法模拟研究不同靶材料对微靶型X射线管出射光斑的影响,讨论不同靶材料和微靶结构对透射式微靶型X射线管的出射光斑尺寸的影响。结果表明:在电子入射能量为100 keV时,微锥形结构靶的光斑尺寸最小在150μm左右,不同靶材料对靶后方出射光斑尺寸有明显影响,随着靶材原子序数增加,出射光斑尺寸开始时逐渐减小,但进一步的增加会使光斑尺寸有一定扩大,呈现抑制趋势;不同微靶结构对光斑尺寸影响与结构有明显关系,圆柱与锥体光斑尺寸差异达到30μm。与传统的透射X射线管相比,在不需要强力电子聚焦设备的情况下,选择微锥形靶结构与银靶材料比采用圆柱钨靶的出射光斑尺寸减小17.93%,更小的光斑尺寸使得X射线成像的精度与准确性得到提高。[Background]Micro target X-ray source has attracted much attention in X-ray microscopy imaging.The focus spot size of X-ray directly affects the spatial resolution of sample.[Purpose]This study aims to investigate the influence of target materials and target microstructures on the emission spot of X-ray tube by simulation.The influence of different target materials on the focus size of X-ray tube is also discussed.[Methods]Monte Carlo simulation code MCNP5 was employed to calculate the focus size with five different target materials,i.e.,Mn,Mo,Silver,Rt,Wu and three different target microstructures,i.e.,hemisphere,cone and cylinder.The full width at half maximum(FWHM)of the light intensity distribution line was used as the standard to measure the spot size.[Results]The results show that the minimum focus size can be achieved by micro cone structure target at the incident electron energy of 100 keV.Moreover,different target materials have obvious influence on the focus size behind the target.The focus size decreases with the increase of the atomic number of the target material at the beginning,but expands to a certain extent with the further increase of the atomic number,showing a suppression trend.The influence of different target microstructures on the focus size is obviously related to the target type.The difference of focus size between cylinder and cone is up to 30μm.Compared with the cylindrical tungsten target,the spot size decreases by 17.93%by using micro cone target structure and the silver target.[Conclusions]Compared with the traditional transmission X-ray tube,the micro target X-ray tube is easy to implement because it does not need strong electron focusing equipment.The methodology and the Monte Carlo simulation results are valuable for guiding the design and optimization of micro target X-ray tube source.

关 键 词：微靶X射线管 靶材料 光斑尺寸 蒙特卡罗模拟 

分 类 号：TL99[核科学技术—核技术及应用]