| Paper |
Title |
Page |
| WEPLT029 |
Intensity Dependent Emittance Transfer Studies at the CERN Proton Synchrotron
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1891 |
| |
- E. Métral, C. Carli, M. Giovannozzi, M. Martini, R.R. Steerenberg
CERN, Geneva
- G. Franchetti, I. Hofmann
GSI, Darmstadt
- J. Qiang
LBNL, Berkeley, California
- R.D. Ryne
LBNL/CBP, Berkeley, California
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An intensive study has been undertaken since the year 2002 to understand better the various high-intensity bottlenecks of the CERN Proton Synchrotron machine. One of these limitations comes from the so-called Montague resonance. High-intensity proton synchrotrons, having larger horizontal than vertical emittance, may suffer from this fourth-order coupling resonance driven by space charge only. In particular, such resonance may lead to emittance sharing and, possibly, beam loss due to vertical acceptance limitation. Experimental observations made in the 2002 and 2003 runs on the Montague resonance are presented in this paper and compared with 3D particle-in-cell simulation results and theoretical predictions.
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| WEPLT053 |
Dynamical Effects of the Montague Resonance
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1957 |
| |
- I. Hofmann, G. Franchetti
GSI, Darmstadt
- J. Qiang, R.D. Ryne
LBNL/CBP, Berkeley, California
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In high-intensity accelerators emittance coupling, known as Montague resonance, may be an issue if the tune split is small. For static tunes within the stop-band of this fourth order space charge driven coupling the final emittances may become equal (equipartition). Using 2D computer simulation we show, however, that slow crossing of the resonance leads to merely an exchange of emittances. In 3D this is similar, if the crossing occurs over a time-scale shorter or comparable with a synchrotron period. For much slower crossing we find, instead, that the exchange may be suppressed by synchrotron motion. We explain this effect in terms of the mixing caused by the synchrotron motion.
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| WEPLT058 |
A Space Charge Algorithm for Ellipsoidal Bunches with Arbitrary Beam Size and Particle Distribution
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1972 |
| |
- G. Franchetti, A. Orzhekovskaya
GSI, Darmstadt
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For the GSI future project beam loss control of a high intensity bunched beam stored in SIS100 for 106 turns is an important issue. In a recent study (G. Franchetti et al., Phys. Rev. ST Accel. Beams 6, 124201 (2003)) an analytical space charge algorithm was proposed, which allowed noise-free calculations over a large number of turns. Here we present a generalization of this algorithm to arbitrary 3D dimensions and arbitrary distributions observing ellipsoidal symmetry. Applications to long-term tracking with space charge are presented
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| WEPLT059 |
Beam Loss Modeling for the SIS100
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1975 |
| |
- G. Franchetti, I. Hofmann
GSI, Darmstadt
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In long term storage dynamic aperture is typically regarded as the quantity which has to be maintained sufficiently large in order to prevent beam loss. In the SIS100 of the GSI future project, a beam size occupying a large fraction of the beam pipe is foreseen. This circumstance requires a careful description of the lattice magnetic imperfections. The dynamic aperture is estimated in relation with an optimization of the SIS100 working point. For a space-charge-free bunched beam, estimates of beam loss are computed and compared with dynamic aperture. The impact of space charge will be discussed, and preliminary results on its effect on dynamic aperture and beam loss are presented.
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| WEPLT060 |
Linear Coupling Theory of High Intensity Beams
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1978 |
| |
- G. Franchetti, I. Hofmann
GSI, Darmstadt
- M. Aslaninejad
IPM, Tehran
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It is planned to use linear coupling in the SIS18 in order to fully or partially equilibrate the transverse emittances before transfer to the projected SIS100 synchrotron. In this paper we show that space charge significantly modifies the coupling mechanism. In particular the width of the stop-band is dominated by the space charge tune shift for weak skew strength. The conditions are discussed, under which slow crossing of the coupling resonance leads to the desired goal of equalizing emittances while maintaining a sufficient matching of the beam to the ring and extraction optics.
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