• J. Pfingstner, D. Schulte
  CERN, Geneva
• M. Hofbaur
  UMIT, Hall in Tirol

One of the major challenges of the CLIC main linac is the preservation of the ultra-low beam emittance. The dynamic effect of ground motion would lead to a rapid emittance increase. Orbit feedback systems (FB) have to be optimized to efficiently attenuate ground motion (disturbance), in spite of drifts of accelerator parameters (imperfect system knowledge). This paper presents a new FB strategy for the main linac of CLIC. It addresses the above mentioned issues, with the help of an adaptive control scheme. The first part of this system is a system identification unit. It delivers an estimate of the time-varying system behavior. The second part is a control algorithm, which uses the most recent system estimate of the identification unit. It uses H2 control theory to deliver an optimal prediction of the ground motion. This approach takes into account the frequency and spacial properties of the ground motion, as well as their impact on the emittance growth.

• M.A. Palmer, J.P. Alexander, M.G. Billing, J.R. Calvey, C.J. Conolly, J.A. Crittenden, J. Dobbins, G. Dugan, N. Eggert, E. Fontes, M.J. Forster, R.E. Gallagher, S.W. Gray, S. Greenwald, D.L. Hartill, W.H. Hopkins, D.L. Kreinick, B. Kreis, Z. Leong, Y. Li, X. Liu, J.A. Livezey, A. Lyndaker, J. Makita, M.P. McDonald, V. Medjidzade, R.E. Meller, T.I. O'Connell, S.B. Peck, D.P. Peterson, G. Ramirez, M.C. Rendina, P. Revesz, D.H. Rice, N.T. Rider, D. L. Rubin, D. Sagan, J.J. Savino, R.M. Schwartz, R.D. Seeley, J.W. Sexton, J.P. Shanks, J.P. Sikora, E.N. Smith, C.R. Strohman, H.A. Williams
  CLASSE, Ithaca, New York
• F. Antoniou, S. Calatroni, M. Gasior, O.R. Jones, Y. Papaphilippou, J. Pfingstner, G. Rumolo, H. Schmickler, M. Taborelli
  CERN, Geneva
• D. Asner
  Carleton University, College of Natural Sciences, Ottawa, Ontario
• L. Boon, A.F. Garfinkel
  Purdue University, West Lafayette, Indiana
• J.M. Byrd, C.M. Celata, J.N. Corlett, S. De Santis, M.A. Furman, A. Jackson, R. Kraft, D.V. Munson, G. Penn, D.W. Plate, M. Venturini
  LBNL, Berkeley, California
• B.T. Carlson
  Grove City College, Grove City, Pennsylvania
• T. Demma
  INFN/LNF, Frascati (Roma)
• R.T. Dowd
  ASCo, Clayton, Victoria
• J.W. Flanagan, P. Jain, K. Kanazawa, K. Kubo, K. Ohmi, H. Sakai, K. Shibata, Y. Suetsugu, M. Tobiyama
  KEK, Ibaraki
• D. Gonnella
  Clarkson University, Potsdam, New York
• W. Guo
  BNL, Upton, Long Island, New York
• K.C. Harkay
  ANL, Argonne
• R. Holtzapple
  CalPoly, San Luis Obispo, CA
• J.K. Jones, A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• D. Kharakh, J.S.T. Ng, M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• M.C. Ross, C.-Y. Tan, R.M. Zwaska
  Fermilab, Batavia
• L. Schächter
  Technion, Haifa
• E.L. Wilkinson
  Loyola University, Chicago, Illinois

The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. Finally a range of EC mitigation methods have been deployed and tested. Measurements of cloud density and its impact on the beam under a range of conditions will be presented and compared with simulations. The effectiveness of a range of mitigation techniques will also be discussed.

Slides

• R. Tomás, B. Dalena, J. Pfingstner, D. Schulte, J. Snuverink
  CERN, Geneva
• J.K. Jones
  Cockcroft Institute, Warrington, Cheshire
• A. Latina
  Fermilab, Batavia
• J. Resta-López
  JAI, Oxford

The CLIC BDS tuning, alignment and feedbacks studies have been typically performed independently and only over particular sections of the BDS. An effort is being put to integrate all these procedures to realistically evaluate the luminosity performance.