Design of a mechanical sealing structure for the synchrotron radiation water-cooled crystal

[Background] The water-cooled crystals at Shanghai synchrotron radiation facility (SSRF) are currently vacuum sealed by colloid bonding. In high-energy synchrotron radiation environments, the colloid is prone to failure that will cause the crystal to flake off. [Purpose] This study aims to introduce the recommended sealing method to avoid the above risks. [Methods] Water-cooled crystal sealing structure was applied to mechanical clamping mechanism. Experimental tests were conducted to obtain surface error in meridian direction of crystal caused by mechanical load and rocking curve. In addition, the water pressure resistance test and leak detection test of the mechanically sealed water-cooled crystal were carried out. [Results] The slope error of the crystal caused by mechanical load is approximately 3.55 μrad (root mean square) which satisfies the performance requirements. Rocking curve test shows that the value of full width at half maximum (FWHM) of the water-cooled crystal of the mechanical sealing structure is 11.86″ which is nearly the same as the FWHM value of 12.24″ of the water-cooled crystal under the original bonding mode, and the difference is about 3%. The results of water pressure resistance and leak detection tests show that the sealing performance of the crystal assembly structure is pretty good. [Conclusions] The water-cooled crystal sealed by mechanical clamping can meet the performance requirements, and it can effectively avoid the occurrence of peeling off event of crystal during work, and provided the necessary guarantee for the stable operation of beam lines at SSRF. (authors)