| Paper |
Title |
Page |
| WEPLT008 |
Simulated Emittance Growth due to Electron Cloud for SPS and LHC
|
1831 |
| |
- E. Benedetto, D. Schulte, F. Zimmermann
CERN, Geneva
- G. Rumolo
GSI, Darmstadt
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The emittance growth caused by an electron cloud is simulated by the HEADTAIL code. The simulation result depends on the number of beam-cloud "interaction points"(IPs), the phase advance between the IPs, the number of macro-particles used to represent beam and cloud, and on the betatron tune. Simulations include a transverse feedback system and, optionally, a large chromaticity, as employed in actual SPS operation. Simulation results for the SPS are compared with observations, and the emittance growth in the LHC is computed as a function of the average electron density.
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| WEPLT009 |
Dynamics of the Electron Pinch and Incoherent Tune Shift Induced by Electron Cloud
|
1834 |
| |
- E. Benedetto, F. Zimmermann
CERN, Geneva
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| |
When a proton bunch passes through an electron cloud, the cloud electrons are attracted by the beam electric field; their density strongly increases near the beam centre. This gives rise to an incoherent proton tune shift, which depends on the longitudinal and radial position within the bunch. We present an analytical description of the 'electron pinch' and the resulting proton tune shift, for a circular symmetry and a Gaussian cloud. Benchmarking and extending the results by computer simulations, we explore the effects of different longitudinal beam profiles and of the nonlinear transverse force.
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| WEPLT012 |
Observation of a Fast Single Bunch Transverse Instability on Protons in the SPS
|
1843 |
| |
- H. Burkhardt, G. Arduini, E. Benedetto, E. Métral
CERN, Geneva
- G. Rumolo
GSI, Darmstadt
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The longitudinal impedance of the SPS has been reduced significantly by hardware modifications over the last years and the threshold for longitudinal instabilities increased accordingly. We now observe a fast transverse instability on high intensity single bunches of low longitudinal emittance. The main observed signature and the threshold dependence on beam parameters is described and compared with theoretical expectations and simulations.
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| THPLT017 |
Review and Comparison of Simulation Codes Modeling Electron-Cloud Build Up and Instabilities
|
2502 |
| |
- F. Zimmermann, E. Benedetto, F. Ruggiero, D. Schulte
CERN, Geneva
- G. Bellodi
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
- M. Blaskiewicz, L. Wang
BNL, Upton, Long Island, New York
- Y. Cai, M.T.F. Pivi
SLAC, Menlo Park, California
- V.K. Decyk, W. Mori
UCLA, Los Angeles, California
- M.A. Furman
LBNL/AFR, Berkeley, California
- A.F. Ghalam, T. Katsouleas
USC, Los Angeles, California
- K. Ohmi, S.S. Win
KEK, Ibaraki
- G. Rumolo
GSI, Darmstadt
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Several computer codes written at various laboratories are employed for modelling the generation and the consequences of an electron cloud. We review the most popular of these programs, which simulate either the build of an electron cloud or the instabilities it produces, and we compare simulation results for identical, or similar, input parameters obtained from the various codes.
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