| Paper |
Title |
Page |
| ROPB004 |
Effect of Lattice and Electron Distribution in Electron-Cloud Instability Simulations for the CERN SPS and LHC
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387 |
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- E. Benedetto, E. Benedetto
Politecnico di Torino, Torino
- G. Arduini, F. Roncarolo, F. Zimmermann
CERN, Geneva
- B. Feng, A.F. Ghalam, T.C. Katsouleas
USC, Los Angeles, California
- G. Franchetti
GSI, Darmstadt
- K. Ohmi
KEK, Ibaraki
- G. Rumolo
CELLS, Bellaterra (Cerdanyola del Vallès)
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Several simulation codes have been adapted so as to model the single-bunch electron-cloud instability including a realistic variation of the optical functions with longitudinal position. In addition, the electron cloud is typically not uniformly distributed around the ring, as frequently assumed, but it is mainly concentrated in certain regions with specific features, e.g., regions which give rise to strong multipacting or suffer from large synchrotron radiation flux. Particularly, electrons in a dipole magnet are forced to follow the vertical field lines and, depending on the bunch intensity, they may populate two vertical stripes, symmetrically located on either side of the beam. In this paper, we present simulation results for the CERN SPS and LHC, which can be compared with measurements or analytical predictions.
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| ROPB007 |
3-D Parallel Simulation Model of Continuous Beam-Electron Cloud Interactions
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549 |
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- A.F. Ghalam, T.C. Katsouleas
USC, Los Angeles, California
- E. Benedetto, F. Zimmermann
CERN, Geneva
- V.K. Decyk, C. Huang, W.B. Mori
UCLA, Los Angeles, California
- G. Rumolo
GSI, Darmstadt
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A 3D Particle-In-Cell model for continuous modeling of beam and electron cloud interaction in a circular accelerator is presented. A simple model for lattice structure, mainly the Quadruple and dipole magnets and chromaticity have been added to a plasma PIC code, QuickPIC, used extensively to model plasma wakefield acceleration concept. The code utilizes parallel processing techniques with domain decomposition in both longitudinal and transverse domains to overcome the massive computational costs of continuously modeling the beam-cloud interaction. Through parallel modeling, we have been able to simulate long-term beam propagation in the presence of electron cloud in many existing and future circular machines around the world. The exact dipole lattice structure has been added to the code and the simulation results for CERN-SPS and LHC with the new lattice structure have been studied. Also the simulation results are compared to the results from the two macro-particle modeling for strong head-tail instability. It is shown that the simple two macro-particle model can capture some of the physics involved in the beam- electron cloud interaction qualitatively.
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| FPAP001 |
Electron Cloud Build-Up Study for DAFNE
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779 |
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- C. Vaccarezza, R. Cimino, A. Drago, M. Zobov
INFN/LNF, Frascati (Roma)
- G. Bellodi
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
- K. Ohmi
KEK, Ibaraki
- M.T.F. Pivi
SLAC, Menlo Park, California
- G. Rumolo
GSI, Darmstadt
- D. Schulte, F. Zimmermann
CERN, Geneva
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After the first experimental observations compatible with the presence of the electron cloud effect in the DAFNE positron ring, a more systematic study has been performed regarding the e-cloud build-up and related instability. The measured field map of the magnetic field has been taken into account in the simulation for elements present in the four 10 m long bending sections, representing 40% of the whole positron ring. The simulation results obtained with different codes are presented and compared with the recent experimental observations performed on the beam instabilities and the vacuum behavior of the positron ring.
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