Liu Jiayin, Ji Zhan, Fan Yichen, Yan Xinxin, Wang Miaomiao, Qin Hongliang
Synchrotron Radiation Facility, Institute of Advanced Science Facilities, Guangming, Shenzhen, Guangdong 518107, People's Republic of China.
J Synchrotron Radiat. 2024 Mar 1;31(Pt 2):260-267. doi: 10.1107/S1600577523010664. Epub 2024 Jan 22.
A method to optimize the thermal deformation of an indirectly cryo-cooled silicon crystal monochromator exposed to intense X-rays at a low-emittance diffraction-limited synchrotron radiation source is presented. The thermal-induced slope error of the monochromator crystal has been studied as a function of heat transfer efficiency, crystal temperature distribution and beam footprint size. A partial cooling method is proposed, which flattens the crystal surface profile within the beam footprint by modifying the cooling contact area to optimize the crystal peak temperature. The optimal temperature varies with different photon energies, which is investigated, and a proper cooling strategy is obtained to fulfil the thermal distortion requirements over the entire photon energy range. At an absorbed power up to 300 W with a maximum power density of 44.8 W mm normal incidence beam from an in-vacuum undulator, the crystal thermal distortion does not exceed 0.3 µrad at 8.33 keV. This method will provide references for the monochromator design on diffraction-limited synchrotron radiation or free-electron laser light sources.
提出了一种优化间接低温冷却硅晶体单色仪热变形的方法，该单色仪在低发射度衍射极限同步辐射源下暴露于强X射线中。研究了单色仪晶体的热致斜率误差与传热效率、晶体温度分布和束斑尺寸的关系。提出了一种局部冷却方法，通过改变冷却接触面积来优化晶体峰值温度，从而使束斑内的晶体表面轮廓变平。研究了最佳温度随不同光子能量的变化情况，并获得了一种合适的冷却策略，以满足整个光子能量范围内的热畸变要求。在来自真空型波荡器的垂直入射光束吸收功率高达300 W、最大功率密度为44.8 W mm的情况下，在8.33 keV时晶体热畸变不超过0.3 µrad。该方法将为衍射极限同步辐射或自由电子激光光源的单色仪设计提供参考。
