| Paper |
Title |
Page |
| MOPP049 |
Collective Effects in the CLIC Damping Rings
|
658 |
| |
- G. Rumolo, J. B. Jeanneret, Y. Papaphilippou, D. Quatraro
CERN, Geneva
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The possible performance limitations coming from collective effects in the CLIC damping rings are the subject of this paper. In particular, the consequences of space charge, due to the very high beam brilliance, and of the resistive wall impedance, due to the locally very small beam pipe, are considered potentially dangerous in spite of the high beam energy. Hence, they have been studied in detail with the HEADTAIL code, which has been modified in order to take into account a finer lattice structure as well as multi-bunch effects of the resistive wall wake field. The study aims at setting the intensity thresholds determined by these phenomena.
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| THPC056 |
Stability Change of Fourth-order Resonance with Application to Multi-turn Extraction Schemes
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3110 |
| |
- M. Giovannozzi, D. Quatraro
CERN, Geneva
- G. Turchetti
Bologna University, Bologna
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Recently, a novel multi-turn extraction scheme was proposed, based on particle trapping inside stable resonances. Numerical simulations and experimental tests confirmed the feasibility of such a scheme for low order resonances. While the 3rd order resonance is generically unstable and those higher than 4th order are generically stable, the 4th order resonance can be either stable or unstable depending on the details of the system under consideration. By means of the normal form approach a general formula to control the stability of the 4th order resonance is derived. Numerical simulations confirm the analytical results and show that by crossing the unstable 4th order resonance the region around the centre of phase space is depleted and particles are trapped only in the four stable islands. This indicates that a four-turn extraction could be envisaged based on this technique.
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