Lawrence Berkeley National Laboratory

Options being considered for the ILC Damping Rings include lattices with circumferences up to 17 km. The circumference, beam current and beam energy place the damping rings in a regime where resistive-wall instability is a concern, particularly as there are very demanding tolerances on the bunch-to-bunch jitter. Generally, it is possible to make good analytical estimates of the coupled-bunch growth rates in a storage ring, but particular features of the damping rings make it desirable to study the coupled-bunch instabilities using simulations. We present the results of simulations (including a bunch-by-bunch feedback system) of the transverse instabilities using a detailed lattice model.