合肥先进光源前端光子吸收器的设计及热分析

合肥先进光源（HALF）将建设成为1台第四代衍射极限储存环光源。HALF的引出光具有更高亮度，能给储存环带来更高的热负载。引光段需设置光子吸收器，以限定引出光的尺寸和吸收其余未使用的同步光，同时减少同步光热负载对储存环超高真空系统的影响。紧凑的衍射极限储存环的物理设计及光子吸收器与真空室连接方式的选择给光子吸收器的设计带来了一系列挑战。在插入式双片型吸收器结构的基础上，综合考虑吸收面形状、水冷结构、安装定位等因素，设计了一种基于CuCrZr材料、与真空室一体、无需单独定位的光子吸收器，并计算其位于弯转角2.74°的弯转磁铁下游光引出段处，被同步光照射的光斑尺寸和辐射功率；采用有限元分析方法对光子吸收器进行热力学模拟，得到辐照后的最高温度约为80 ℃，最大应力为20.8 MPa，最大热变形为0.05 mm。结合制作材料CuCrZr在高热负载下的许用准则，确定了光子吸收器结构的合理性。此研究为合肥先进光源中前端区光子吸收器的设计提供了重要的理论依据。

Design and thermal analysis of front-end photon absorber at HALF

The Hefei Advanced Light Facility (HALF) is a diffraction limited storage ring (DLSR).The extracted light of HALF has higher brightness resulting in higher heat load to the storage ring. The redundant synchrotron radiation is absorbed by the photon absorber located in the front-end to protect the ultrahigh vacuum system of DLSR. A special design of the photon absorber is required due to the compact physical design. Considering the toothed surface profile, cooling channel, and installation, we propose a photon absorber made of CuCrZr without additional positioning on the basis of the two-piece vertical absorber. The spot size and power of the radiation from the bending magnet with a bending angle of 2.74° are calculated. The thermal-mechanical simulations based on the finite element analysis method show acceptable results. The maximum thermal deformation, temperature, and stress are 0.05 mm, 80 ℃, and 20.8 MPa, respectively, indicating that the new absorber works in a safe range. The present study provides a critical theoretical basis for the design of the photon absorber in the front-end of HALF.