• E. Adli, R. Corsini, A.E. Dabrowski, D. Schulte, H. Shaker, P.K. Skowronski, F. Tecker, R. Tomás
  CERN, Geneva

An automatic beam steering application for CTF 3 is being designed in order to automatize operation of the machine, as well as providing a test-bed for advanced steering algorithms for CLIC. Beam-based correction including dispersion free steering have been investigated. An approach based on a PLACET on-line model has been tested. This paper gives an overview of the current status and the achieved results of the CTF3 automatic steering.

• A. Grudiev, H.-H. Braun, D. Schulte, W. Wuensch
  CERN, Geneva

Recently the CLIC study has changed the operating frequency and accelerating gradient of the main linac from 30 GHz and 150 MV/m to 12 GHz and 100 MV/m, respectively. This major change of parameters has been driven by the results from a novel main linac optimization procedure. The procedure allows simultaneous optimization of operating frequency, accelerating gradient, and many other parameters of CLIC main linac. It takes into account both beam dynamics (BD) and high power rf constraints. BD constraints are related to emittance growth due to short- and long-range transverse wakefields. Rf constraints are related to rf breakdown and pulsed surface heating of the accelerating structure. The optimization figure of merit includes the power efficiency, measured as a ratio of luminosity to the input power as well as a quantity proportional to investment cost.

• G. Burt, P.K. Ambattu, R.G. Carter, A.C. Dexter, M.I. Tahir
  Cockcroft Institute, Lancaster University, Lancaster
• C. Adolphsen, Z. Li, A. Seryi, L. Xiao
  SLAC, Menlo Park, California
• C.D. Beard, D.M. Dykes, P. Goudket, A. Kalinin, L. Ma, P.A. McIntosh
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• L. Bellantoni, B. Chase, M. Church, T.N. Khabiboulline
  Fermilab, Batavia
• R.M. Jones
  UMAN, Manchester
• A. Latina, D. Schulte
  CERN, Geneva

Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favours a 3.9 GHz superconducting, multi-cell cavity as the ILC solution, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are special issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.