Trajectory Correction Algorithms on the latest Model of the CLIC Main LINAC

Abstract

Control of beam emittance is a key issue in the design of future linear colliders. Results depend closely on the assumptions made for the alignment tolerances of the various linac components. Processes involving several correctors and beam position monitors help either to reduce the emittance blow-up or to increase the tolerances beyond the values provided by simpler ‘one-to-one’ schemes. ‘Dispersion-Free’ or ‘WakeFree’ algorithms require a simulation of the effects to be corrected, by lattice quadrupole detuning. Wakefield effects can also be measured, for example by current modulation as in the ‘Measured-Wakefield’ and ‘Dispersive-Wakefield’ processes. For the Compact LInear Collider (CLIC) these algorithms, so far tested in the thin-lens approximation and assuming continuous scaling with energy of quadrupole strength and RF section length, are now applied on a more realistic structure of the main linac. Their implementation is described and the performances achieved in terms of the alignment tolerances are presented. Special emphasis is placed on the merits of the most powerful ‘Dispersive Wakefield’ process.