Key technologies and the performance measuring methods in variable included angle plane grating monochromator
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摘要: 变包含角平面光栅单色器具有分辨率高和光通量高等优点,被广泛应用于各科研领域,并且随着相关领域研究的不断深入,迫切需要提高其光谱分辨率,以满足使用需求。为研究探索极高分辨率变包含角平面光栅单色器,结合上海同步辐射光源光束线,重点研究影响单色器分辨率的关键因素;对单色器光学元件表面热负载进行分析,设计冷却系统,降低热负载产生的影响;研究变包含角平面光栅单色器转角精度等检测方法。结果表明,根据推导出的变包含角平面光栅单色器光学放大倍数与单色器分辨率的关系式,达到优选极高分辨率工作模式的目的;加入冷却系统后,单色器前置平面镜因受热负载影响而产生的最大斜率误差由8.1 μrad降到3.1 μrad;设计可应用于变包含角光栅单色器分辨率达5×104的转角精度检测方法,检测精度可达0.026"。该研究将为第三代同步辐射光源中建造极高分辨变包含角单色器提供帮助。Abstract: The variable-included-angle plane grating monochromator is broadly used in high performance soft X-ray due to its superior performance, such as high throughput and high resolution. With the development of Science, improving and optimizing the resolution of variables-included-angle plane grating monochromator is necessary and urgently. In order to study and explore the ultra-high resolution of variables-included-angle plane grating monochromator in synchrotron radiation, some issues were researched in this work. Firstly, the relationship between working modes of variables-included-angle plane grating monochromator with different cff is emphatically researched. According to the relationship, the high resolution working modes of the monochromator can be selected. Secondly, we studied the effects of high heat load on the optical system by using the simulation software and designed an appropriate cooling system in the optical elements to decrease the effect of heat load on monochromator. The results indicated that the slope error of plane mirror declined from 8.1 μrad to 3 μrad. Lastly, we studied the testing methods of the variables-included-angle grating monochromator with the resolution of already reaching 5×104. And the measuring accuracy of angel is 0.026".Those studies will provide some help for designing the monochromator with ultra-high resolution in the third generation synchrotron radiation.
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图 4 光学放大倍数分别为1.8和1.85两种情况的能量分辨率对比图[10]
Figure 4. Comparison of resolutions with different cff of 1.8 and 1.85
表 1 上海同步辐射光源参数[9]
Table 1. Main parameters of storage ring of SSRF
参数名称 数值 运行能量 E/GeV 3.5 环周长 L/m 432 自然水平发射度ε/(mm·rad) 3.90 耦合系数k 0.01 束流流强:多束团(单束团)/mA 200~300(5) 单元数目 N 20 -
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