Single and Multi-bunch Wakefields Effects in the TESLA Linac

Once the tolerable emittance growth of a beam accelerated in the main linac of a linear collider, departing from a perfect transport line, is fixed, all the tolerances on the various errors, like injection jitter, magnets and structures misalignment, can be in principle determined. The maximum allowable magnitudes of the errors however are closely related to the correction schemes considered in the machine. Furthermore, one correction method, which is favourable for single bunch effects, may be disastrous for multi-bunch effects, and vice versa. This observation led us to develope a tracking code named DILEM, which combines simultaneously single and multi-bunch effectst and includes numerous correction techniques, from orbit steering to wakefields compensation methods. Thus, we are able to evaluate the emittance dilution reduction not only for the first bunch but also for the entire bunch train. After a brief description of the code, results of simulations applied on the TESLA linac parameters are presented. In addition to the beam orbit corrections, like “one-to-one”, “Dispersion Free ” or “Wake Free ” [l], further correction methods of emittance dilution, like non dispersive bumps or fast kickers [2] are also tested. The discrepancies in the results depending on wether the short- and long range effects are separately or simultaneously taken into account, are then discussed