The influence of parasitic modes on beam dynamics for the European spallation source linac

The European Spallation Source (ESS) linac will consist of three families of superconducting RF cavities to accelerate protons to a final beam energy of 2.5 GeV for collision with the target. Beam induced HOMs in these cavities may drive the beam unstable and increase the cryogenic load, severely limiting the operation of the linac. The effect of these modes on the beam quality is investigated in detail using a numerical code dedicated to beam-HOM interaction.