INFLUENCE OF THE CAVITY FIELD FLATNESS AND EFFECT OF THE PHASE REFERENCE LINE ERRORS ON THE BEAM DYNAMICS OF THE ESS LINAC

The particle longitudinal dynamics is affected by errors on the phase and amplitude of the electro-magnetic field in each cavity that cause emittance growth, beam degradation and losses. One of the causes of the phase error is the change of the ambience temperature in the LINAC tunnel, in the stub and in the klystron gallery that induces a phase drift of the signal travelling through the cables and radio frequency components. The field flatness error of each multiple cell cavity is caused by volume perturbation, cell to cell coupling, tuner penetration, etc. In this paper the influences of these two types of errors on the beam dynamics are studied and tolerances for keeping beam quality within acceptable limits are determined.