Mechanical system of the double-period undulator prototype for SHINE

The Shanghai High repetition rate XFEL and Extreme light facility (SHINE) is under construction and aims at generating X-rays between 0.4 and 25 keV with three FEL beamlines at repetition rates of up to 1 MHz [1-3]. The three FEL beamlines of the SHINE are referred to as the FEL-I, FEL-II, and FEL-III. Shanghai Advanced Research Institute(SARI) will manufacture 14 double-period undulators for the FEL-II. The double-period undulator is equipped with two rows of magnetic array of different period lengths on the same girder, and magnetic force compensation is achieved by translating the upper and lower magnetic array with a certain longitudinal offset. A double-period undulator prototype has been developed by SARI. This paper describes the design, simulation, and measurement results of mechanical system.