Update on Ion Studies

The effect of ions has received one of the highest priorities in R&D for the damping rings of the International Linear Collider(ILC). It is detrimental to the performance of the electron damping ring. In this note, an update concerning the ion studies for the ILC damping ring is given. We investigate the gap role and irregular fill pattern in the ring.The ion density reduction in different fills is calculated analytically. Simulation results are also presented.