Design and test of the beam-based alignment sextupole experimental mover prototype for HEPS

Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory. The mechanical design of a beam-based alignment sextupole mover should be developed. The motion accuracy of the mover should be better than 5 μm under 450 kg load of sextupoles. The movement range is required to be ± 0.3 mm in both horizontal direction and vertical direction. And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz. Purpose The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness. And to find the difficulties of development of this mover. Method Interferometer is used to measure the motion accuracy, and pressure accelerometer is used to test the mover equivalent stiffness. Combining with the actual measurement results of equivalent stiffness, the natural frequency of the magnet support system is simulated. Result The motion accuracy reaches to 5.3 μm in vertical direction and 1 μm in horizontal direction, respectively. The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system. Unwanted movement coupling has occurred during the mover exercises in vertical direction. Conclusions Through the research of experimental mover prototype, the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load. However, further researches and improvements are necessary to fix the coupling error during the vertical movement.