共查询到20条相似文献,搜索用时 15 毫秒
1.
Wan-Li Shang 《中国物理 B》2021,30(11):116101-116101
Plasma density and temperature can be diagnosed by x-ray line emission measurement with crystal, and bent crystals such as von Hamos and Hall structures are proposed to improve the diffraction brightness. In this study, a straightforward solution for the focusing schemes of flat and bent crystals is provided. Simulations with XOP code are performed to validate the analytical model, and good agreements are achieved. The von Hamos or multi-cone crystal can lead to several hundred times intensity enhancements for a 200μm plasma source. This model benefits the applications of the focusing bent crystals. 相似文献
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Weiwei Dong Quan Cai Fugui Yang Xu Liu Jiaowang Yang Qianshun Diao Peng Liu Xiaowei Zhang Lingfei Hu 《Journal of synchrotron radiation》2018,25(5):1346-1353
The sagittal‐bent Laue monochromator can provide an ideal way to focus high‐energy X‐ray beams. However, the anticlastic curvature induced by sagittal bending has a great influence on the crystal performance. Thus, characterizing the bent‐crystal shape is very important for predicting the performance of the bent‐crystal monochromator. In this paper the crystal profile is measured by off‐line optical metrology and on‐line X‐ray experiments. The off‐line results showed that the bent‐crystal surface could be well fitted to a saddle surface apart from a redundant cubic term which was related to the different couples applied on the crystal. On‐line characterization of the meridional and the sagittal radius of the bent crystal includes double‐crystal topography and ray‐tracing measurement. In addition, the double‐crystal topography experiment could be used as a quick diagnostic method for the bending condition adjustment. The sagittal radius of the bent crystal was characterized through a ray‐tracing experiment by using a particularly designed tungsten mask. Moreover, rocking curves under different bending conditions were measured as well. The results were highly consistent with analytical results derived from the elastic theory. Furthermore, radii along different vertical positions under various bending conditions were measured and showed a quadratic relationship between the vertical positions and the meridional radii. 相似文献
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Bingbao Mei Songqi Gu Xianlong Du Zhongliang Li Hanjie Cao Fei Song Yuying Huang Zheng Jiang 《X射线光谱测定》2020,49(1):251-259
A wavelength-dispersive X-ray spectrometer based on von Hamos geometry for in/ex situ resonant inelastic X-ray scattering (RIXS) studies at BL14W1-X-ray absorption fine structure (XAFS) beamline of Shanghai Synchrotron Radiation Facility (SSRF) is reported. The design considerations and the operational characteristics of the spectrometer are described in detail. With a Si(444) bent crystal, the spectrometer provides an energy range from 8 to 9 keV, which enables the measurement of K-edge X-ray spectroscopy of some transition metal complexes and L-edge X-ray spectroscopy of some 5d transition metal complexes. Based on von Hamos geometry, the process of the collection of RIXS is considerably simplified. The collection of full RIXS planes of tungstic samples requiring spectral resolutions is presented, demonstrating the speciation capabilities of the instrument. Taking the series of oxide-derived copper catalysts for carbon dioxide electrochemical reduction as the research model, the in situ RIXS were measured to probe dynamic changes in electronic structure. Finally, the comparison between in situ RIXS and in situ conventional XAFS is presented, demonstrating more competitive spectral resolution of RIXS. 相似文献
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The X‐ray Powder Diffraction (XPD) beamline at the National Synchrotron Light Source II is a multi‐purpose high‐energy X‐ray diffraction beamline with high throughput and high resolution. The beamline uses a sagittally bent double‐Laue crystal monochromator to provide X‐rays over a large energy range (30–70 keV). In this paper the optical design and the calculated performance of the XPD beamline are presented. The damping wiggler source is simulated by the SRW code and a filter system is designed to optimize the photon flux as well as to reduce the heat load on the first optics. The final beamline performance under two operation modes is simulated using the SHADOW program. For the first time a multi‐lamellar model is introduced and implemented in the ray tracing of the bent Laue crystal monochromator. The optimization and the optical properties of the vertical focusing mirror are also discussed. Finally, the instrumental resolution function of the XPD beamline is described in an analytical method. 相似文献
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An optimized two crystal arrangement for X-ray optics 总被引:1,自引:0,他引:1
Modification of the Schwarzschild optics for applications in hard X-ray imaging is discussed. The conditions necessary to achieve a high spatial resolution with two toroidally bent crystals in the Bragg geometry are formulated, and the focusing properties of the system are numerically simulated using the ray tracing method. It is predicted that such a system could provide a spatial resolution considerably higher than the resolution of the presently available X-ray optics. 相似文献
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球面晶体背光成像系统是一种重要的惯性约束聚变诊断技术,为了验证球面晶体背光成像系统性能,优化成像系统结构,利用光线追踪软件SHADOW对该系统背光成像进行模拟,对成像系统参量中成像物体位置、球面晶体弯曲半径和布拉格角等进行了模拟分析。结果表明:布拉格角为57和65的球面晶体背光成像系统,当成像物体厚度或者物体放置的误差a=1 mm,晶体弯曲半径误差R=3 mm,布拉格角误差=0.1 mrad时,在子午面和弧矢面光线追踪模拟的2个成像系统的相对放大率与经过相对放大率公式计算的结果比较吻合,说明参量的微小变化对成像系统的相对放大率影响较小,成像系统性能稳定可靠。 相似文献
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X‐ray free‐electron lasers (XFELs) generate sequences of ultra‐short spatially coherent pulses of X‐ray radiation. A diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ΔE/E? 2 × 10?6, is proposed. This is much better than for most modern X‐ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single‐crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from a metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. It is shown that the DFS can be used in a wide energy range from 5 keV to 20 keV. 相似文献
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由于可有效降低高热负载的影响, Laue弯晶是插入件辐射高通量密度硬X射线(30 keV以上)聚焦、 准直和单色化的最有效的光学元件.研究其聚焦光学特性,对发展高性能、高稳定的Laue弯晶单色器具有重要意义. 采用自行发展的光线追迹软件较为系统地研究了Laue弯晶的聚焦特性, 分析了入射光性质及弯晶参数对聚焦光斑、焦距、发散度等主要光学参数的影响. 结果表明,衍射能量越高,聚焦光斑越小,并趋于稳定值;弯曲半径越小,聚焦光斑越小, 并在其达到一阈值时得到聚焦光斑的极小值,之后随着弯曲半径的变小,由于像差等因素的影响, 聚焦光斑反而变大;晶体越厚,聚焦光斑越大,呈线性正比关系.对于衍射光发散度, 其随着衍射能量的增大而变小,并趋于稳定值;其与晶体曲率呈线性正比关系. 同时通过研究得到弯晶各参数的合理选择范围. 相似文献
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在惯性约束聚变光谱诊断物理实验研究中,晶体衍射后X射线光谱信号较弱,需要高收光效率及宽频谱范围的光谱诊断仪器.在传统锥面弯曲晶体基础上提出变曲率弯晶多能点成像技术,该技术具有宽频谱范围、强聚焦能力、高光谱分辨的特点.在晶体衍射成像结构设计中,由于能够确保成像光线的旋转对称性,因此在原理上可消除传统弯晶X射线衍射成像像差.利用研制的变曲率面石英晶体对钛靶X射线源进行X射线聚焦检测,并与同种材料的平面晶体进行收光效率对比,实验结果表明该变曲率面石英晶体的收光效率可以达到平面石英晶体的100倍,检测X射线能量范围为4.51~5.14keV.该晶体谱仪结合X射线条纹相机能够检测宽频谱范围的微弱X射线信号,条纹相机探测面可与晶体检测光路方向垂直布局. 相似文献
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用于X射线时空分辨测量的弯晶谱仪 总被引:6,自引:6,他引:0
为了测量激光聚变产生的0.2~0.37 nm范围内的等离子体X射线, 设计了一种基于空间和时间分辨的聚焦型弯晶谱仪. 将在700℃时弯曲后的LiF(2d=0.403 nm)晶体作为色散元件, 布喇格衍射角的变化范围为30~67.5°, 弯晶粘贴在离心率和焦距分别为0.9586和1350 mm的椭圆形不锈钢基底上. 利用弯晶谱仪配X光CCD相机在星光Ⅱ激光(0.35 μm, 60~80J, 700 ps)装置上摄取了钛平面靶发射的X射线光谱, 实验结果表明它的光谱分辨率能达到0.001 nm. 相似文献
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Ari‐Pekka Honkanen Roberto Verbeni Laura Simonelli Marco Moretti Sala Giulio Monaco Simo Huotari 《Journal of synchrotron radiation》2014,21(1):104-110
Theoretical and experimental studies are presented on properties of spherically bent analyser crystals for high‐resolution X‐ray spectrometry. A correction to the bent‐crystal strain field owing to its finite surface area is derived. The results are used to explain the reflectivity curves and anisotropic properties of Si(660) and Si(553) analysers in near‐backscattering geometry. The results from the calculation agree very well with experimental results obtained using an inelastic X‐ray scattering synchrotron beamline. 相似文献
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晶体器件中的光线追迹法 总被引:3,自引:2,他引:1
本文以Wollaston棱镜为例将作者原先提出的晶体中光线轨迹公式用于具有多个折射面的晶体器件,阐明公式中各物理量的计算方法,把它与坐标转换关系相结合,提出了一种较简单的光线追迹法,用以研究晶体器件的象差.为晶体器件设计提供了一种新方法. 相似文献
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We present valence-to-core X-ray emission spectroscopy of Ti, TiO, and TiO2 by means of a double crystal von Hamos spectrometer based on full-cylinder highly annealed pyrolytic graphite mosaic crystals. We demonstrate that, using a double crystal configuration, an energy resolution of E/ΔE ≈ 2,700 can be achieved in a compact setup using cylindrically curved optics with a radius of curvature of 50 mm. The stated energy resolution proved to be high enough to identify and determine chemical shifts of the Kβ2,5 and Kβ″ emission lines of both oxides. The experimental results are supported by calculations with the ab initio package OCEAN and compared with literature values. 相似文献
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Rong Huang Mati Meron Naresh Kujala Raul A. Barrea 《Journal of synchrotron radiation》2010,17(5):644-652
Micro‐focusing optical devices at synchrotron beamlines usually have a limited acceptance, but more flux can be intercepted if such optics are used to focus secondary sources created by the primary optics. Flux throughput can be maximized by placing the secondary focusing optics close to or exactly at the secondary source position. However, standard methods of beamline optics analysis, such as the lens equation or matching the mirror surface to an ellipse, work poorly when the source‐to‐optics distance is very short. In this paper the general characteristics of the focusing of beams with Gaussian profiles by a `thin lens' are analysed under the paraxial approximation in phase space, concluding that the focusing of a beam with a short source‐to‐optics distance is distinct from imaging the source; slope errors are successfully included in all the formulas so that they can be used to calculate beamline focusing with good accuracy. A method is also introduced to use the thin‐lens result to analyse the micro‐focusing produced by an elliptically bent trapezoid‐shaped Kirkpatrick–Baez mirror. The results of this analysis are in good agreement with ray‐tracing simulations and are confirmed by the experimental results of the secondary focusing at the 18‐ID Bio‐CAT beamline (at the APS). The result of secondary focusing carried out at 18‐ID using a single‐bounce capillary can also be explained using this phase‐space analysis. A discussion of the secondary focusing results is presented at the end of this paper. 相似文献
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A. Ya. Lopatin V. I. Luchin N. N. Salashchenko N. I. Chkhalo A. P. Shevelko O. F. Yakushev 《Technical Physics》2010,55(7):1018-1023
We investigate the spectral characteristics of new focusing multilayer structures used as dispersive elements in a high-transmission X-ray spectrometer with cylindrical geometry (Hamos scheme): W/B4C structures in a wavelength range of λ = 8.0?9.5 Å and Cr/Sc structures in a range of λ = 30?40 Å (the range is not accessible for natural crystals). The results of demonstration experiments on laser-produced plasma spectra recording are considered. It is shown that the luminosity of a Hamos spectrometer with multilayer dispersive elements is an order of magnitude higher than the luminosity of grazing-incidence grating spectrographs with a comparable spectral resolution. 相似文献