• V.P. Yakovlev, I.G. Gonin, T.N. Khabiboulline, A. Latina, A. Lunin, V. Poloubotko, N. Solyak
  Fermilab, Batavia

Different couplers are described that allow the reduction of both transverse wake potential and RF kick in the SC acceleration structure of ILC. A simple rotation of the couplers reducing the RF kick and transverse wake kick is discussed for both the main linac and bunch compressors, along with possible limitations of this method. Designs of a coupler unit are presented which preserve axial symmetry of the structure, and provide reduced both the RF kick and transverse wake field.

• M. Fitterer, A.-S. Müller
  KIT, Karlsruhe
• E. Adli, H. Burkhardt, B. Dalena, G. Rumolo, D. Schulte
  CERN, Geneva
• I. Ahmed
  NCP, Islamabad
• A. Latina
  Fermilab, Batavia

We report about generic halo and tail simulations and estimates. Previous studies were mainly focused on very high energies as relevant for the beam delivery systems of linear colliders. We have now studied, applied and extended these simulations to lower energies as relevant for the CLIC drive beam.

• F. Stulle, L. Rinolfi, D. Schulte
  CERN, Geneva
• A. Ferrari
  Uppsala University, Uppsala
• A. Latina
  Fermilab, Batavia

Prior to acceleration in the main linac, the particle beams created in the centrally located injector have to be transported to the outer ends of the CLIC site. This transport should not only preserve the beam quality but also shape, characterize and tune the phase space distribution to match the requirements at the entrance of the main linac. Hence, the performance of the transport downstream of the damping rings up to the main linac, the so called RTML, is crucial for the overall performance of CLIC. The RTML consists of a variety of components like bunch compressors, accelerating cavities, spin rotators, collimators, diagnostics sections, feedback and feedforward systems, each serving a distinct function. We discuss the different parts of the RTML and the beam dynamics challenges connected to them. Their status is outlined and results of beam dynamics simulations are presented.

• A. Saini
  University of Delhi, Delhi
• A. Latina, J.-F. Ostiguy, K. Ranjan, N. Solyak, V.P. Yakovlev
  Fermilab, Batavia

It is well known that Insertion of a coupler into a RF cavity breaks the rotational symmetry of the cavity, resulting in an asymmetric field. This asymmetric field results in a transverse RF Kick*. This RF kick transversely offsets the bunch from the nominal axis & it depends on the longitudinal position of the particle in the bunch. Also, insertion of coupler generates short range transverse wake field** which is independent from the transverse offset of the particle. These effects cause emittance dilution and it is thus important to study their behavior & possible correction mechanisms. These coupler effects, i.e. coupler’s RF kick & coupler's wake field are implemented in a beam dynamics program, Lucretia. Calculations are done for Main Linac. For ILC like Lattices Results are compared with analytical results. and a good agreement has been found.

*N.Solyak et al, “RF Kick in the ILC Acceleration Structure. ” MOPP042.pdf (EPAC 08).
** N.Solyak et al, “Transverse Wake Field Simulation for the ILC Acceleration Structure”. MOPP043 pdf (EPAC 08).

• A. Latina, I.G. Gonin, K. Ranjan, N. Solyak, V.P. Yakovlev
  Fermilab, Batavia

In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the acceleration structure. The beam emittance dilution caused by the couplers is calculated for the main linac and bunch compressor of ILC. It is shown that for the bunch compressor this effect may constitute a problem, and modification of the coupler unit may be necessary in order to preserve the cavity axial symmetry.