Two-dimensional tilt control of electron bunch for X-ray free electron laser

Abstract

We present a method to control the two-dimensional transverse tilt of the electron bunch originated after the bunch compressor, affecting the X-ray free-electron laser performance. A head-tail tilt in both horizontal and vertical planes leads to a difference between the projected and the slice Twiss parameters, making it difficult to match the electron beam optics to the design one. The primary beam-tilt sources taken into accounts are the CSR generated in the chicane (horizontal tilt) and the misalignment of the high-order cavity used to linearize the compression process (vertical tilt). We show the experimental measurements performed to correct the both-plane beam tilts by using a tweak quadrupole and a skew quadrupole, respectively, placed in the chicane.