Introduction . X-ray free-electron laser (XFEL) has been widely used in various research fields [ 1 , 2 ], including chemistry, bioscience, material science, etc. In order to meet the demands of more advanced research, some technologies such as fully coherent XFEL [ 3 ], high-repetition rate XFEL [ 4 , 5 , 6 , 7 , 8 ], multi-beamline [ 9 , 10 ], and multi-beam energy [ 11 , 12 ] operation of XFEL had been developed. Shanghai High-Repetition-Rate XFEL and Extreme L...