Mechanical design and experimental test of a remote-controlled quadrupole mover for SINAP FEL projects

Abstract Background: The high position accuracy of the key parts such as the quadrupole magnet relative to the beam center is very important for the Free Electron Laser(FEL) equipment, and will directly affect the quality of the beam. Purpose: This study aims to realize the precise beam-based aligment of the quadrupole by mechanical design of a remote-controlled quadrupole mover. Methods: Beam based alignment(BBA) technique was applied to adjusting the center position of quadrupole with a remote-controlledhigh accuracy mover and its control system. Experimental tests and analysis for the quadrupole mover by the different feedback control were carried out for the undulator segments of the soft X-ray FEL(SXFEL) in Shanghai and the Dalian Coherent Light Source(DCLS) project in China. Results: The positioning accuracy and repeatability error of the quadrupole mover is less than 3 μm by the grating ruler feedback control, but it is more than 3 μm by the rotary encoder feedback control. Conclusion: The mechanical design and experimental tests of the quadrupole mover areaccomplished. The positioning accuracy and repeatability of the quadrupole mover meet the design indices by the grating ruler feedback control. (authors)