Beam dynamics and wake-field simulations for the CLIC main linacs

TL;DR

This paper presents detailed simulations of wake-fields and beam dynamics in the CLIC linear collider's X-band linacs, focusing on emittance preservation through wake-field damping strategies.

Contribution

It provides new simulation results on long-range wake-fields and beam emittance dilution with realistic initial beam offsets in CLIC linacs.

Findings

Wake-field effects can significantly dilute beam emittance without damping.

Simulations show the importance of wake-field damping for beam quality.

Initial beam offsets impact emittance growth in the linacs.

Abstract

The CLIC linear collider aims at accelerating multiple bunches of electrons and positrons and colliding them at a centre of mass energy of 3 TeV. These bunches will be accelerated through X-band linacs, operating at an accelerating frequency of 12 GHz. Each beam readily excites wake-fields within the accelerating cavities of each linac. The transverse components of the wake-fields, if left unchecked, can dilute the beam emittance. The present CLIC design relies on heavy damping of these wake-fields in order to ameliorate the effects of the wake-fields on the beam emittance. Here we present initial results on simulations of the long-range wake-fields in these structures and on beam dynamics simulations. In particular, detailed simulations are performed, on emittance dilution due to beams initially injected with realistic offsets from the electrical centre of the cavities.