Research On Clamping Method Of Reflector Used In Soft X-ray Free-electron Laser Beamline

Combing the advantages of synchrotron radiation and conventional laser,freeelectron-laser has the properties of high brightness,full coherence,and short pulse time,so it plays an irreplaceable role in many scientific fields.Reflector is an important optical element in the free-electron-laser beamline.It has the functions of beam deflection,shaping,polarization,etc.In addition,it also can suppress higher harmonics.With the progress of free-electron-laser technology,the experimental stations have more and more different requirements,the surface shape accuracy of reflector have become higher and higher.Therefore,reducing the surface slope error of the reflector is extremely important for the construction of a high-level free-electron-laser device.This thesis focuses on the reflectors in the Shanghai soft X-ray free-electron-laser SBP live cell imaging beam line,and aims to reduce the rectangular reflector's surface slope error caused by its own weight.The main research contents can be listed as follows:1)Gravity is the main factor of reflector's surface slope errors.The plane stress theory is used to analyze the surface slope error of the reflector because of gravity.In order to reduce the surface slope error caused by self-weight,a gravity compensation scheme was proposed based on Bessel point theory,and the clamping position of the reflector was optimized using finite element analysis method.2)The beamline has different working modes,and the minimum surface slope error and space positioning error,required by the reflector,are very sensitive to its complex stress conditions.Based on the study of the reflector clamping method,this thesis proposes a lifting scheme and a bottom supporting scheme for the downwardreflector,and establishes the three-dimensional models.Finite element analysis has been performed for both two schemes,including static and dynamic analysis.The results show that the surface slope error of the reflector equipped with clamping mechanism can meet the requirements and run stably.3)The magnitude of the clamping force is an important factor that affecting the surface slope error of the reflector.The stringent requirements of the surface slope error and the increase in the length of the reflector have increased the debugging difficulty.This thesis sets up a pressure test system,tested the clamping force during the surface error debugging process,and finally obtained the suitable clamping force of the reflector online.4)The surface slope error of the reflector was tested using the NOM surface shape detection equipment belonged to Shanghai Synchrotron Radiation Facility(SSRF).At the same time,the assembly process of the reflector and method of how to reduce the surface shape error were summarized.This thesis focuses on the key technologies and assembly methods of the clamping mechanism to compensate for the surface slope error caused by the reflector's own weight.During the entire research process,the design and analysis of the reflector clamping mechanism were completed,and the installation and surface adjustment of the reflector clamping mechanism were summarized.Finally,the magnitude of clamping force was tested.The reflector clamping mechanism meets the design requirement and run stably.These results have certain reference value for the design of reflector clamping mechanism,and provide experience for the further assembly process of the reflector and adjustment of surface slope error.