Design of the CLIC Drive Beam Recombination Complex

The CLIC Drive Beam Recombination Complex (DBRC) is designed to compress beam pulses from a current of 4 A to 100 A before using them to produce RF power in the deceleration lines. The beam is transported isochronously through a complex system consisting of a delay loop, two combiner rings and final turn around. The system is designed to preserve transverse and longitudinal emittances. During the optics design, chromaticity and non-linear dispersion were identified as the main single particle dynamics causes for transverse emittance growth. Different sextupole families are used to compensate these chromatic effects while keeping isochronicity. The bunch length is also adjusted to minimize coherent synchrotron radiation effects on bunch length, energy spread and transverse emittance. Finally, the injection scheme of the combiner rings was improved by making the time-variable bump created with help of the RF deflectors truly achromatic.