Beam-Beam Issues With Two Interaction Points in eRHIC

In this article, we study the beam-beam interaction related issues with two interaction points in the current eRHIC ring-ring design. We carried out strong-strong beam-beam simulation in a 2-d bunch intensity scan. We observed coherent beam-beam instability and emittance blowup with 2 collisions per turn at lower bunch intensities than the case with only 1 collision per turn. To deliver collisions to the two experiments simultaneously, we proposed a new bunch filling pattern to avoid 2 collisions per turn for any electron or proton bunch. We proved that the parasitic beam-beam effect with the new bunch filling pattern is negligible.