Finite element analysis for the Bragg crystal of D-line at SSRF (Conference Presentation)

The Dynamic Beamline (D-line) is a combination of ED-XAS beamline and IR beamline. Among the D-line ED-XAS Branch, a Si (111) crystal with the thickness of 1 millimeter is used in Bragg geometry. The crystal has to be bent with a radius of curvature ranging from 2 to 20 m and receives heat load of 30 watts. To meet the need of dynamical focusing and heat cooling, the crystal is immersed in a water-cooled liquid eutectic In/Ga alloy bath. We perform bending and thermal analyses for the crystal, using Ansys software. The size of crystal is 300mm*20mm and it is held in the four-point bender system. The footprint on the crystal is 0.46mm*78. To reduce its deformation, an indirect water cooled method is adopted. The water film coefficient is 3000W/mm2C, and the reference temperature is 17 degree Celsius. The thermal conductivity for Si and In/Ga is 149 W/mC and 28 W/mC, respectively. After thermal analysis, the maximum temperature is about 48 degree Celsius. By mean of structural analysis, the deformation and stress distribution of the crystal were calculated as well. The RMS tangential slope error of the centerline on the footprint is 5μrad or so, which can meet the need of beamline.