• R. Tomás, H.-H. Braun, J.-P. Delahaye, A. Marin, D. Schulte, F. Zimmermann
  CERN, Geneva
• D. Angal-Kalinin, J.K. Jones
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S. Bai, J. Gao, X.W. Zhu
  IHEP Beijing, Beijing
• P. Bambade, M. Renier
  LAL, Orsay
• Y. Honda, S. Kuroda, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• A. Scarfe
  UMAN, Manchester
• A. Seryi, G.R. White, M. Woodley
  SLAC, Menlo Park, California

The CLIC Final Focus System has considerably larger chromaticity than those of ILC and its scaled test machine ATF2. We propose to reduce the IP betas of ATF2 to reach a CLIC-like chromaticity. This would also allow to study the FFS tuning difficulty as function of the IP beam spot size. Both the ILC and CLIC projects will largely benefit from the ATF2 experience at these ultra-low IP betas.

• S. Pei, M.J. Hogan, T.O. Raubenheimer, A. Seryi
  SLAC, Menlo Park, California
• H.-H. Braun, R. Corsini, J.-P. Delahaye
  CERN, Geneva

Funding: Work supported by the DOE under contract DE-AC02-76SF00515.

Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFA-based Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements.

• A. Seryi, J.W. Amann, P. Bellomo, B. Lam, D.J. McCormick, J. Nelson, J.M. Paterson, M.T.F. Pivi, T.O. Raubenheimer, C.M. Spencer, M.-H. Wang, G.R. White, W. Wittmer, M. Woodley, Y.T. Yan, F. Zhou
  SLAC, Menlo Park, California
• D. Angal-Kalinin, J.K. Jones
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• R. Apsimon, B. Constance, C. Perry, J. Resta-López, C. Swinson
  JAI, Oxford
• S. Araki, A.S. Aryshev, H. Hayano, Y. Honda, K. Kubo, T. Kume, S. Kuroda, M. Masuzawa, T. Naito, T. Okugi, R. Sugahara, T. Tauchi, N. Terunuma, J. Urakawa, K. Yokoya
  KEK, Ibaraki
• S. Bai, J. Gao
  IHEP Beijing, Beijing
• P. Bambade, Y. Renier, C. Rimbault
  LAL, Orsay
• G.A. Blair, S.T. Boogert, V. Karataev, S. Molloy
  Royal Holloway, University of London, Surrey
• B. Bolzon, N. Geffroy, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• P. Burrows
  OXFORDphysics, Oxford, Oxon
• G.B. Christian
  ATOMKI, Debrecen
• J.-P. Delahaye, D. Schulte, R. Tomás, F. Zimmermann
  CERN, Geneva
• E. Elsen
  DESY, Hamburg
• E. Gianfelice-Wendt, M.C. Ross, M. Wendt
  Fermilab, Batavia
• A. Heo, E.-S. Kim, H.-S. Kim
  Kyungpook National University, Daegu
• J.Y. Huang, W.H. Hwang, S.H. Kim, Y.J. Park
  PAL, Pohang, Kyungbuk
• Y. Iwashita, T. Sugimoto
  Kyoto ICR, Uji, Kyoto
• Y. Kamiya
  ICEPP, Tokyo
• S. Komamiya, M. Oroku, T.S. Suehara, T. Yamanaka
  University of Tokyo, Tokyo
• A. Lyapin
  UCL, London
• B. Parker
  BNL, Upton, Long Island, New York
• T. Sanuki
  Tohoku University, Graduate School of Science, Sendai
• A. Scarfe
  UMAN, Manchester
• T. Takahashi
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• A. Wolski
  Cockcroft Institute, Warrington, Cheshire

ATF2 is a final-focus test beam line that attempts to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction is well advanced and beam commissioning of ATF2 has started in the second half of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.

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