【作者】 李中亮；

【导师】 徐朝银；

【作者基本信息】 中国科学技术大学 ， 同步辐射及应用， 2011， 博士

【摘要】 同步辐射光的优异特性为多学科交叉研究和相互融合提供了平台,随着科技的进步,越来越多的实验需要更高的光子通量。在现有光源条件下,通过改善光束线系统设计和研制新型光学元件来提高照射在样品上光子密度和成像质量。本论文依托国家同步辐射实验室XAFS光束线改造工程和ESRF光学实验室多层膜技术的研究课题,对用于动态能量扫描的大曲率弧矢聚焦双晶单色器中的关键技术和多层膜作为高能同步辐射分光元件中的相关问题作了系统研究。完成对大曲率弧矢聚焦双晶单色器的核心部件设计、加工、测量和使用。对高能同步辐射光照射下的多层膜表面的热变形进行了系统的分析。主要工作包括以下几个方面:1.弧矢聚焦双晶单色器第一晶体的热载变形和第二晶体弧矢弯曲产生鞍型变形的分析研究依据NSRL-XAFS现有的光源条件和光学参数,模拟分析有、无水冷两种情况下,第一晶体光学表面的热变形对单色器衍射效率的影响都较小,光斑在晶体表面的移动引起的面形误差在实验要求范围内;分析了弧矢弯曲晶体产生鞍型变形的机理,理论计算鞍型变形对单色器衍射效率的影响。鉴于目前常用的几种抑制鞍型变形的方法,模拟背面加肋板、黄金比例和等分变形槽三种晶体弯曲过程中光学表面面型误差的变化,通过优化结构参数,分别设计、加工制作试件,利用LTP对弯曲过程中的鞍型变形进行测量,并与理论计算相对比,获得许多有用数据,为大曲率弧矢聚焦双晶单色器的工程研制,提升NSRL-XAFS光束线性能奠定了基础。2.大曲率弧矢弯曲复合晶体的研制利用有限元分析晶体模型弯曲时的应力,结果晶体大曲率弯曲时存在横向断裂的危险。基于等分变形槽晶体的设计理念提出复合晶体的研制模型,即:将晶片附着在钛合金基底上,按照理论优化的占空比深切变形槽,呈平面矩形光栅形状的胚胎,弯曲后各独立晶条围成正多边柱面体,上层晶体作衍射,下层钛合金作弹性弯曲,既可克服鞍形变形,又能在钛合金弹性范围内实施大曲率弯曲。其光学成像原理等同于将入射的光束分成若干子束,经每个窄条晶体衍射后叠加汇聚在样品上。对复合晶体模型优化计算,确定复合晶体的结构参数;设计加工试件样品;用LTP测量的晶体模型的鞍型变形,与有限元分析结果比较;搭建激光模拟光路对复合晶体模型的聚焦性能和弯曲的稳定性进行试验测量压弯过程中光斑的漂移;理论计算晶体模型的衍射效率。3.高能同步辐射光学中多层膜的热缓释技术研究该课题主要依据ESRF光学实验室研制应用于高能同步辐射的多层膜分光元件,对受高热载的多层膜表面温度分布进行分析,模拟光斑大小对多层膜基底表面热变形的影响,优化比较多层膜基底不同冷却位置面形误差的变化,通过侧面切槽基底改变温度分布,进而降低表面的面型误差。采用灵活的梯度温度冷却方法改变基底的温度分布,可实现特定曲面的多层膜。同时结合同步辐射对多层膜的要求,采用磁控溅射镀膜,降低镀膜随机和非随机厚度的差值,减小镀膜之间和基底表面的粗糙度,可以有效提高多层膜的反射率。通过上述研究得到结论是:抑制鞍型变形的三种晶体模型,在弯曲过程中都可NS控RL制-X表AF面S面光形束线误改差造小后于的晶弧体矢本聚征焦单角色宽器的中1,/5对;同大步曲辐率射复光合水晶平方体向应聚用焦在,样品处的光子密度比目前的双平晶单色器提高一个量级;侧面切槽多层膜基底冷却在高热载同步辐射光照射下,有效的抑制表面形变,降低面形误差。更多还原

【Abstract】 Synchrotron radiation source has been widely used in many fields as an essential instrument for its excellent character. There are more and more experiment need higher photon fluxes. In order to get higher photon intensity, some systemic research on key technology of the large curvature sagittal focusing monochromator for dynamical energy scanning by support of NSRL-XAFS beamline upgrading project and multilayer for synchrotron white beam based on ESRF study of the multilayer. Design, manufacture, examining and application of the key part of the large curvature sagittal focusing crystal monochromator were done. Thermal deformation of the multilayer for white beam that study at ID06 of ESRF was researched.1. Research on the sagittal focusing crystal monochromator and related technology There was small influence on the diffraction efficiency of the first crystal thermal deformation with or without water cooling, and the slope error within the required of experiments when the light spot drift on the crystal. The author introduced the principle how the bended crystal produce the anticlastic deformation and made finite analysis. design and outline measurement of the stiffening ribs, the golden value and slabs slot-cut, which were used to minimize the anticlastic distortion. We got much useful data and supply stronger warrant to the study of the large curvature sagittal focusing monochromator.2. Development of assembly sagittal focusing crystals with large curvatures For the bending radius under 1m, the tensile stresses of the crystal were comparable to the failure tensile stresses. An assembly crystal which cements the silicon strips with the tops of titanium stiffening ribs was designed and its slope error were evaluated by finite element analysis and were measured with LTP. The focusing properties and the bending stability of the assembly crystal were measured by laser beamline. The author calculated the diffraction of the assembly crystal and measured the light drift when cured the crystal model.3. Research of the multilayer monochromator The multilayer monochromators for synchrotron beamline are usually produced by magnetron and ion beam sputter deposition. Long trace profiler, atomic force microscope and transmission electron microscopy were used to measure the curvature and roughness of multilayers. The important imperfections in multilayers are random or pseudo-random variations in the thicknesses of layers due to changes in deposition rates, deviations from perfect flatness in the surface of the substrate, microscopic or macroscopic surface roughness in the layers and diffusion between layers. Based on cooling optimization, the top-side cooling of the multilayer substrate is the best choice. The slope error of the multilayer substrate with smart cross section is greatly reduced, which because there is no temperature gradient in the thickness.Some conclusions could be made, which were shown as follows: The slope error of the model that minimize the anticlastic distortion when bending the crystal was less than the Darwin width of the crystal; Compared the double plane crystal, the intensity of the large curvature sagittal focusing monochromator focus the light on the sample increased one order of magnitude; The thermal slope error of the multilayer substrate wKietyh swmoarrdt cs:r o Sssa gseitcttailo nf oisc ulesisnsg t h amno n0o.6chμrroamd ator, slope error, anticlastic distortion,更多还原