圆锥形X光导管的传输特性研究

利用光线追迹原理建立的圆锥形X光导管的计算模型,对圆锥形X光导管传输特性进行了系统的理论研究。通过对X射线经过锥管的光强分布计算,得到光源尺寸和锥管入口直径共同影响光强分布形式的结论。计算了锥管功率密度增益K随距离锥管出口不同位置f2的变化规律。研究了功率密度增益随光源尺寸的变化规律。最后以等效距离为标准讨论了锥管的优化设计。     

软X射线光导纤维传输特性

 为优化设计软X射线聚束透镜,使之与软X射线源配合能最大限度地获得高强度软X射线束,在北京同步辐射装置软X光站3W1B束线上,对不同能量软X射线（50～1 500 eV）在不同规格毛细管光导纤维中的传输特性进行研究。研究结果表明：玻璃毛细管对软X光有较高的传输效率,毛细管内径越小,曲率越小,光子能量越小,则传输效率越大;使用含硼（B）量高的DM308型号玻璃材料拉制成内直径为0.45 mm﹑外直径为0.6 mm的毛细管组成的软X光聚束透镜有较高的传输效率,该规格毛细管可以将能量为250 eV的X射线传播方向改变26°后,其出射能量是入射能量的12%;使用由该规格毛细管设计的软X射线聚束透镜同软X射线点光源组合,收光角可以达到30°,透镜焦点处的功率密度是不使用透镜时的104倍。     

亚波长锥形波导的电磁场分布及传输特性

利用时谐电磁场和波导理论,推导出锥形卒心金属波导中球横电模和球横磁模各电磁场分量的解析表达式,对输出孔径是哑波长尺寸的锥形空心金属波导内球横电模和球横磁模的传输特性及与锥形空心金属波导内光透射率有关的时间平均能量密度分布进行了详细的分析.运用数值求解获得的精确本征值,进一步讨论了光波波长、锥形波导的长度、输出孔径以及锥角对锥形空心金属波导内时间平均能量密度分布的影响.研究结果表明,时间平均能量密度分布在锥形金属波导内呈现准周期性变化,且周期与传输模式、锥角及光波波长有关.并且,在传输径向坐标上会出现一个最大值,最大值的位置随光波波长、锥角发生强烈的变化.     

直锥形光纤传输性质的研究

光纤通信的发展日新月异,光纤在信息的传输方面起着越来越重要的作用.通过把传输光纤的一端拉制成锥形,研究了光信号在锥形光纤中的传播行为.根据标量波动方程,运用高斯近似法,从理论上说明了光信号在锥形光纤中的传输特性和能量损耗,分析了光功率在光纤中的分布、光纤中基模场的模半径与光纤芯径的关系、光纤中光的传输模式与光纤芯径的关系、锥形光纤的传输效率与锥形光纤尖端直径的关系等.在实验上,用剪断法测量了锥形光纤的传输效率随锥形光纤圆锥角的变化关系.通过选取一系列锥角的大小,测出相应的传输效率,作出?湫是?并用具体数据进行半定量计算,得出锥形光纤顶端锥体的角度及其变化愈大愈光滑,锥形过渡区越短,传输效率就越高的结论.     

X射线在毛细导管中传输的理论研究

给出了X射线在毛细导管中传输特性的简明而系统的理论描述.在这个理论描述的基础上,建 立了X射线在毛细导管中传输的计算模型,编制了X射线在毛细导管中传输的计算程序.利用 编制的X射线在毛细导管中传输计算程序得到的数值结果和实验结果符合得很好. 关键词： 毛细导管 X射线 传输模型     

利用单飞秒激光脉冲驱动类氖钛X射线激光的研究

提出了一种利用单飞秒激光脉冲驱动类氖钛X射线激光的物理方案.利用自相似方法研究了不同脉冲前沿的单飞秒激光辐照钛平板靶产生的类氖钛X射线激光等离子体的特性,得到了电子温度、电子密度和定标长度三者的定标律,讨论了给定输入参数下各定标律曲线的特性.研究表明,利用单个飞秒激光能够实现X射线激光的产生,而且脉冲前沿强度随时间增长平缓的飞秒激光有利于驱动X射线激光.本研究为实验上实现单飞秒激光脉冲驱动X射线激光提供了一种新的方案.     

一种新型单毛细管X光学器件

利用高精度光纤拉丝塔制作了高品质的锥管,并且对锥管的束斑大小、传输效率和增益因子进行了测量。测量结果表明,锥管的束斑大小可以达到20μm以下,在8.04 keV处,锥管的传输效率为13.86%,距离锥管出口端2.5 mm处,增益因子为85。同时,还利用光线追迹软件shadow对锥管的束斑大小、传输效率和增益因子进行了理论模拟,理论模拟结果与实验中测量的结果符合得较好。测试结果表明,利用锥管会聚X射线,可以得到比目前经常使用的X光透镜更小的束斑。     

同步辐射掠出射X射线荧光分析薄膜膜厚

掠射X射线荧光分析为薄层和多层膜特性分析提供了潜在的可能. 尤其是可以探测膜层厚度、界面形貌和组成. 以北京同步辐射光源作激发光源, 采用掠出射方法测试了Si基片上不同厚度的单层Cr膜样品, 测试结果与理论计算基本符合. 同时观察到一定厚度的薄膜样品产生的掠出射X射线荧光的干涉现象.     

锥形光纤的偏振特性

随着光通信技术的不断发展，光纤的应用越来越广泛，而锥形光纤以其独特的传光方式越来越多地应用于光纤连接、成像及测量等领域。实验测定了不同锥角和不同长度锥形光纤的偏振特性。理论上，根据麦克斯韦方程组以及边界条件给出了光在理想光纤中的场分布，阐明了实际光纤中光的传输特性。论证了锥形光纤长度与其偏振特性的关系，进而利用几何光学方法对锥形光纤锥角与其偏振特性的关系作了定性说明。并用具体数据进行了定量计算，得出偏振光经锥形光纤传输或耦合后再传输到其终端所得到均是椭圆偏振光的结论。     

高Q值薄壁液芯毛细管微腔电场传感器

为提高电场传感器的抗电磁干扰能力、灵敏度和稳定性,将高Q值薄壁液芯毛细管微腔和电泳效应结合,增强回音壁模共振微腔对外加电场的感知能力,并进行了实验验证.基于时域有限差分法得到了液芯毛细管微腔回音壁模式共振特性随毛细管直径、壁厚等结构参数的变化规律,发现随着壁厚变薄灵敏度增加.采用熔融拉锥法制备了直径为86μm,壁厚约为2μm的薄壁毛细管微腔,通过高精度位移平台实现了锥形光纤和毛细管微腔的高效率耦合,测得回音壁模式Q值为2.8×10^6.毛细管微腔内注入不同浓度的蛋白质溶液,利用电泳原理和蛋白质分子在缓冲溶液里带电的特性,实现的最大电场传感灵敏度为10.6 pm/(kV/m).     

高线密度X光透射光栅衍射效率

高线密度X光透射光栅是各种高分辨光栅摄谱仪的核心色散元件,为了获得较高的光谱分辨率,工作在2~5 keV能区的光谱仪需要使用5000 l/mm的X射线透射光栅。为了获得光栅的绝对衍射效率,采用同步辐射光在多个能点对5000 l/mm的X光透射光栅进行衍射效率实验标定,通过光栅相对衍射效率拟合获得了光栅结构参数,与光栅结构测量结果非常接近。然后,采用衍射效率的矩形栅线模型,计算得到了光栅的绝对衍射效率。     

Applications of X-ray synchrotron microtomography for non-destructive 3D studies of paleontological specimens

Paleontologists are quite recent newcomers among the users of X-ray synchrotron imaging techniques at the European Synchrotron Radiation Facility (ESRF). Studies of the external morphological characteristics of a fossil organism are not sufficient to extract all the information for a paleontological study. Nowadays observations of internal structures become increasingly important, but these observations should be non-destructive in order to preserve the important specimens. Conventional microtomography allows performing part of these investigations. Nevertheless, the best microtomographic images are obtained using third-generation synchrotrons producing hard X-rays, such as the ESRF. Firstly, monochromatisation avoids beam hardening that is frequently strong for paleontological samples. Secondly, the high beam intensity available at synchrotron radiation sources allows rapid data acquisition at very high spatial resolutions, resulting in precise mapping of the internal structures of the sample. Thirdly, high coherence leads to additional imaging possibilities: phase contrast radiography, phase contrast microtomography and holotomography. These methods greatly improve the image contrast and therefore allow studying fossils that cannot be investigated by conventional microtomography due to a high degree of mineralisation or low absorption contrast. Thanks to these different properties and imaging techniques, a synchrotron radiation source and the ESRF in particular appears as an almost ideal investigation tool for paleontology. PACS 01.30.Cc; 07.05.Hd; 68.37.Yz; 29.20.Lq; 81.70.Tx     

Refractive Lenses for Microscopy and Nanoanalysis

X-rays offer indispensable opportunities for science, medicine, and technology due to a large variety of exceptional properties. The large penetration depth of X-rays in matter allows one to investigate the inner structures of an object without destructive sample preparation, or inside special sample environments, such as chemical reactors or pressure cells. In this way, X-rays are ideally suited to study physical and chemical processes in situ and operando. In addition, X-ray analytical techniques, such as X-ray diffraction, fluorescence, and absorption, provide atomic-scale structure information, elemental concentrations, and the chemical state of a given elemental species inside the sample. With the advent of highly brilliant synchrotron radiation sources of the third generation, it became possible to combine X-ray analytics with microscopy, triggering the rapid development of new types of optics for X-rays, amongst which refractive X-ray lenses have progressed at a spectacular pace.     

Water jet cooled silicon monochromators

The First Autumn School on Engineering Material Science with Neutrons and Synchrotron Radiation took place in the conference center “Haus am Schüberg” in Ammersbek near Hamburg, Germany, from October 10 to 14, 2005.

Neutron and photon sources offer unique possibilities by complementary use of the radiations for structure analyses of advanced engineering materials. By using neutrons and photons delivered by a synchrotron radiation source, information about material microstructures can be obtained non-destructively in the near-surface region as well as in the bulk of samples and components. Compared to conventional laboratory X-rays, the spatial resolution and in-depth information achievable using synchrotron radiation and neutrons can be increased by up to several orders of magnitude. The new possibilities for microstructure analyses for advanced materials and multi-material systems meet with increasing demands from the materials engineering point of view. In materials engineering, the establishment and refinement of relationships between microstructure parameters and macroscopic properties requires information on different length and time scales, both covering several orders of magnitude.     

The X-ray emission from the knots in 3C 120

3C 120 is a Seyfert galaxy with a well detected X-ray jet. We investigate the X-ray emission of its five jet knots and fit their spectral energy distributions (SEDs) from the radio to the X-ray bands with a single-zone lepton model. We find that the SEDs of knots k7, s2, and s3 can be explained by synchrotron radiation, and the X-rays are the simple extension of the radio-optical emission component, but that of the inner knot k4 requires the IC/CMB model, in which the X-rays are due to the inverse Compton scattering of the cosmic microwave background photons by relativistic electrons in the jet with a beaming factor δ∼14. The outer knot k25 is resolved into a three-part sub-structure. It is shown that the fitting of the X-rays from this knot with the IC/CMB model needs an extraordinary beaming factor δ∼15–25 for a jet at the kpc scale. If the X-rays of knot k25 are produced by synchrotron radiation similar to k7, s2, and s3, they may be contributed by a relativistic electron population whose radiations in other wavelengths are not detected.

     

Microscopic imaging and holography with hard X-rays using Fresnel zone-plates

The imaging properties of a Fresnel zone-plate (FZP) were used for magnified imaging of microobjects using hard X-rays. The experiments were done using 14 keV synchrotron radiation. The coherence properties of the radiation produced by an undulator allowed the recording of real images and holograms from an object in one single exposure. These images result from the positive and the negative first order diffracted beams respectively. The X-ray microscope worked at an X-ray magnification factor of 12 and could resolve structures of 0.3 μm in size. By going to slightly defocused conditions we obtained magnified images of the holographical nearfield diffraction pattern (in-line holograms) of the object.     

基于同步辐射X射线相衬显微CT技术的竹木复合材料胶合界面特征研究

第三代同步辐射光源X射线相位衬度显微CT能获得样品内部结构的边缘增强图像,实现对低Z材料成像。利用上海同步辐射光源X射线相衬显微成像技术,实现了竹木复合材料中EPI和MUF胶合界面和胶黏剂渗透特征的无损探测,并基于这些特征分析了几种不同加工工艺对胶黏剂在木材和竹材中渗透的影响。该技术为人造板工艺解剖学研究提供了一种重要无损检测手段。     

透射光栅对软X射线衍射效率的研究

在北京同步辐射源上，对无底衬透射光栅在844eV X射线能量点的绝对衍射效率进行了实验标定，利用光栅模型，得到了光栅所有结构参数，并由此得到了透射光栅对100—2000eV能区软X射线的各级绝对衍射效率理论计算曲线. 关键词：     

X-ray structure analysis of the polycrystalline complex of copper (II) chloride with 1,5-dimethyltetrazole. Application of synchrotron radiation and laboratory diffraction data

The structure of the complex of copper (II) chloride CuCl₂ L, where L is 1,5-dimethyltetrazole, was refined with the Rietveld method using three sets of powder diffraction data obtained at laboratory diffractometers and with synchrotron radiation. The comparative analysis of the results of the structure refinement was performed; this analysis showed that the application of the laboratory data for the wavelength of X-rays λ = 1.7902 Å (CoKα radiation) provides the structural characteristics of the complex comparable in accuracy with those obtained using the synchrotron radiation for the wavelength λ = 1.5443 Å.