Beam Dynamics Studies for CLIC Drive Beams and for Focusing Highly Chromatic Beams

The main linac 30 GHz RF source called drive beam consists in a succession of structures resonating at this frequency, loaded by convenient trains of high charge bunches for transfer of the energy (group velocity # 0) to the structures of the main linac. Maximum efficiency is obtained if one can focus the drive beam up to the point where particles with minimum energy reach energy zero. At this point, some particles still have their initial energy, then all the spectrum is represented. The challenge is to keep the beam envelope within the iris, with this chromaticity, with the misalignments of beam at entry, misalignments of structures and quadrupoles, and also with the transverse wake they create. Parameters, lay-out and results correspond to October 97 state of studies.