SIMULATION STUDIES ON COUPLER WAKEFIELD AND RF KICKS FOR THE INTERNATIONAL L INEAR COLLIDER WITH MERLIN * ∗

One of the critical issues in the design of the superconducting cavities for the International Linear Collider (ILC) is the influence of the RF and higher order mode (HOM) couplers on the beam dynamics. Both types of couplers break the rotational symmetry of the cavity and introduce non-vanishing transverse wakefields even on the cavity axis. Furthermore, the couplers introduce an asymmetry into the accelerating RF field and thereby additional transverse field components. We have implemented both effects following the calculations presented previously [1] into the MERLIN library [2]. This allows us to study the influence of wakefield and RF kicks on the beam dynamics, the bunch shape and the overall performance of the ILC for the present design and a proposed modification of the coupler orientation.