Automation of beam based alignment for the PAL-XFEL undulator line

An automated method of quadrupole beam based alignment in an X-ray free electron laser (XFEL) undulator line is proposed. To realize the automatic beam based alignment (BBA) independently of operator׳s skill and efforts, the procedure is simplified. Simulation results on the BBA technique using two alignment stages for the Pohang Accelerator Laboratory XFEL׳s (PAL-XFEL) undulator line is carried out. After a standard mechanical alignment the quadrupoles are expected to be aligned to 100 μm rms from our previous experience. A rough alignment method in this study is able to align the quadrupoles to about 40 μm rms without any pre-handling of electron beam orbit or quadrupoles position. At the second stage, the singular value decomposition (SVD) method is applied to perform a fine alignment in which the trajectory of an electron beam is controlled within 5 μm rms to the ideal orbit. All procedures are programmable to perform the BBA automatically.