Emittance growth study using 3DE code for the ERL injector cavities with various coupler configurations

We compute emittance growth in electron bunches in high gradient accelerating cavities due to field nonlinearities and phase dependence associated with the finite bunch length. The determination of the emittance is based on tracking of individual particles through tabulated, 3-dimensional, electromagnetic fields. No symmetry is assumed. The fields for the structure, including input coupler, are calculated using MAFIA or MWS[CST Microwave Studio, User Guide, CSTGmbH, Budinger Str. D-64289 Darmstadt, Germany]. We examine particle trajectories RF focusing and emittance growth of injector cavities with various coupler configurations under study for Cornell Energy-Recovery-Linac proposal [V.Shemelin, SRF notes 021028-08].