Simulation of the head-tail instability of colliding bunches

Abstract

A numerical simulation of a possible coherent beam-beam instability of the head-tail type is presented. The studied model employs a linearized coherent beam-beam interaction and takes complete account of the bunch length, including the deformation of the colliding bunches during their overlap. Measured head-tail mode spectra from the VEPP-2M collider are compared with the results of the analytical model and tracking. A computer code for evaluation of the coherent mode increments, which was used for analysis of possible ways to stabilize the beam-beam system, is described.