| Paper |
Title |
Page |
| THPC056 |
Stability Change of Fourth-order Resonance with Application to Multi-turn Extraction Schemes
|
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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| THPC086 |
Transverse Mismatch Oscillations of a Bunched Beam in Presence of Space Charge and External Nonlinearities
|
3188 |
| |
- C. Benedetti, G. Turchetti
Bologna University, Bologna
- G. Franchetti, I. Hofmann
GSI, Darmstadt
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The damping of transverse mismatch oscillations depends on the combined effect of space charge as well as external nonlinearities. Previous studies of this problem for high intensity beams in a synchrotron have not included the combined effect of synchrotron oscillation and external nonlinearities on mismatch. In this paper we explore by 2.5D particle in cell simulations the effect on emittance growth, halo and beam loss caused by space charge, synchrotron oscillation and external nonlinearities. Different tunes are considered in order to understand the importance of external nonlinearities as function of the distance of the working point from the resonance condition.
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