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Dugan, G.

Paper Title Page
MOPE091 Techniques for Observation of Beam Dynamics in the Presence of an Electron Cloud 1197
 
  • M.G. Billing, G. Dugan, R.E. Meller, M.A. Palmer, M.C. Rendina, N.T. Rider, J.P. Sikora, C.R. Strohman
    CLASSE, Ithaca, New York
  • R. Holtzapple
    CalPoly, San Luis Obispo, CA
 
 

During the last several years CESR has been studying the effects of electron clouds on stored beams in order to understand their impact on future linear-collider damping ring designs. One of the important issues is the way that the electron cloud alters the dynamics of bunches within the train. Techniques for observing the dynamical effects of beams interacting with the electron clouds have been developed. These methods will be discussed and examples of measurements will be presented.

 
TUPD022 CesrTA Retarding Field Analyzer Modeling Results 1970
 
  • J.R. Calvey, J.A. Crittenden, G. Dugan, S. Greenwald, Z. Leong, J.A. Livezey, M.A. Palmer
    CLASSE, Ithaca, New York
  • C.M. Celata
    Cornell University, Ithaca, New York
  • M.A. Furman, M. Venturini
    LBNL, Berkeley, California
  • K.C. Harkay
    ANL, Argonne
 
 

Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA, particularly in regions of high magnetic field, understanding these measurements can be nontrivial. This paper will examine different methods for interpreting RFA data via cloud simulation programs. Possible techniques include postprocessing the output of a simulation code to predict the RFA response, and incorporating an RFA model into the program itself.

 
TUPD024 Progress in Studies of Electron-cloud-induced Optics Distortions at CesrTA 1976
 
  • J.A. Crittenden, J.R. Calvey, G. Dugan, D.L. Kreinick, Z. Leong, J.A. Livezey, M.A. Palmer, D. L. Rubin, D. Sagan
    CLASSE, Ithaca, New York
  • M.A. Furman, G. Penn, M. Venturini
    LBNL, Berkeley, California
  • K.C. Harkay
    ANL, Argonne
  • R. Holtzapple
    CalPoly, San Luis Obispo, CA
  • M.T.F. Pivi, L. Wang
    SLAC, Menlo Park, California
 
 

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent tune shifts for a variety of electron and positron beam energies, bunch current levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low-energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters such as the synchrotron radiation flux, its interaction with the vacuum chamber wall, the beam emittance and lattice optics, as well as to those of the various contributions to the electron secondary yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modelling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

 
TUYMH02 Electron Cloud at Low Emittance in CesrTA 1251
 
  • 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.

 

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Slides

 
WEPE097 Recommendation for the Feasibility of More Compact LC Damping Rings 3578
 
  • M.T.F. Pivi, L. Wang
    SLAC, Menlo Park, California
  • C.M. Celata, M.A. Furman, M. Venturini
    LBNL, Berkeley, California
  • J.A. Crittenden, G. Dugan, M.A. Palmer
    CLASSE, Ithaca, New York
  • T. Demma, S. Guiducci
    INFN/LNF, Frascati (Roma)
  • K.C. Harkay
    ANL, Argonne
  • O.B. Malyshev
    Cockcroft Institute, Warrington, Cheshire
  • K. Ohmi, K. Shibata, Y. Suetsugu
    KEK, Ibaraki
  • Y. Papaphilippou, G. Rumolo
    CERN, Geneva
 
 

As part of the International Linear Collider (ILC) collaboration, we have compared the electron cloud effect for different Damping Ring designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of a shorter damping ring with respect to the electron cloud build-up and related beam instability. These studies were carried out with beam parameters of the ILC Low Power option. A reduced damping ring circumference has been proposed for the new ILC baseline design and would allow to considerably reduce the number of components, wiggler magnets and costs. We also briefly discuss the plans for future studies including the luminosity upgrade option with shorter bunch spacing, the evaluation of mitigations and the integration of the CesrTA results into the Damping Ring design.