EMITTANCE DILUTION SIMULATIONS FOR NORMAL CONDUCTING AND SUPERCONDUCTING LINEAR COLLIDERS

An electron (or positron) multi-bunch train traversing several thousand accelerator structures can be distorted by the long-range wakefields left behind accelerated bunches. These wakefields can at the very least, give rise to a dilution in the emittance of the beam and, at worst can lead to a beam break up instability. The authors investigate the emittance dilution that occurs for various frequency errors (corresponding to small errors made in the design or fabrication of the structure) for the GLC/NLC (Global Linear Collider/Next Linear Collider) and for TESLA (TeV Energy Superconducting Linear Accelerator). Resonant effects, which can be particularly damaging, are studied for X-band and L-band linacs.