SINGLE BUNCH EMITTANCE PRESERVATION IN XFEL LINAC

The single bunch emittance preservation in booster and main linacs of European XFEL project is presented. The wakefield and chromatic dilution of the beam emittance caused by free betatron oscillations, cavity and modules offset misalignments and random tilts are evaluated. The effects of cavities misalignments correlation along the linac are discussed. The effects of quadrupole misalignments and the corresponding trajectory steering based on one-to-one correction technique are given. The residual chromatic emittance dilution of the corrected trajectory is evaluated.