Study of beam-beam effects in eRHIC with self-consistent beam-beam simulation

Beam-beam effects in eRHIC was studied with a self-consistent (strong-strong) beam-beam simulation by using the particle-in-cell method. Beam-beam limits were examined as thresholds of the onset of coherent beam-beam instability. For the proposed luminosity, the bunch intensities optimized in consideration of the beam-beam effect were discussed. It was also found that the modulation in the beam-beam interaction on PACMAN bunches in eRHIC can induce a high-order coherent beam-beam instability with a spontaneous oscillation of transverse beam size and a chaotic oscillation of beam centroid. As the beam-beam interaction in eRHIC is traditionally considered as strong-weak or very unsymmetrical, the beam-beam problem in eRHIC represents an example of the coherent beam-beam effect in the strong-weak case of beam-beam interactions.