Beam Dynamics in the ESS Linac under the Influence of Monopole and Dipole HOMs

The European Spallation Source (ESS), planned to be operational in 2019, is anticipated to be the worlds most intense neutron source. The total beam power will be 5 MW. We focus on the impact of manufacturing errors on the beam quality. In particular we assess the emittance dilution which occurs due to Higher Order Modes (HOMs) excited at a harmonic of the bunch frequency. We also discuss some alignment issues pertaining to the cavities.