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| TUZAAB01 |
Equilibrium Beam Distribution in Electron Storage Rings near Synchrobetatron Coupling Resonances
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789 |
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Linear dynamics in a storage ring can be described by the one-turn map matrix. In the case of a resonance where two of the eigenvalues of this matrix are degenerate, a coupling perturbation causes a mixing of the uncoupled eigenvectors. A perturbation formalism is developed to find eigenvalues and eigenvectors of the one-turn map near such a linear resonance. Damping and diffusion due to synchrotron radiation can be obtained by integrating their effects over one turn, and the coupled eigenvectors can be used to find the coupled damping and diffusion coefficients. Expressions for the coupled equilibrium emittances and beam distribution moments are then derived. In addition to the conventional instabilities at the sum, integer, and half-integer resonances, it is found that the coupling can cause an instability through antidamping near a sum resonance even when the symplectic dynamics are stable. E. G., the case of linear synchrobetatron coupling is analyzed where the coupling is caused by dispersion in the rf cavity, or by a crab cavity. Explicit closed-form expressions for the sum/difference resonances are given along with the integer/half-integer resonances.
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Slides
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| TUZAAB02 |
Recent Developments in Understanding Beam Loss in High-intensity Synchrotrons
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794 |
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Recent advances in understanding space-charge-induced beam loss and emittance growth have been achieved, which allow quantitative predictions for large number of turns (exceeding 105). In this talk we review the theoretical model of trapping by space charge effects, simulation results and experimental findings obtained at the CERN Proton Synchrotron and the heavy ion synchrotron SIS18 at GSI. The impact of these effects on the beam loss budget/beam loss control for heavy ion beams in the SIS100 synchrotron in the FAIR project will be presented. Applications of these mechanisms to e-cloud space charge interaction with hadron beams in the LHC will be also be discussed.
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Slides
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| TUZAAB03 |
Emittance Measurement and Modeling for the Fermilab Booster
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799 |
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- X. Huang
- S.-Y. Lee
IUCF, Bloomington, Indiana
- K. Y. Ng
Fermilab, Batavia, Illinois
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Funding: DOE/NSF
We systematically measured the emittance evolution of a fast cycling proton accelerator on a turn-by-turn basis under various beam intensities via an ionization profile monitor (IPM). The vertical emittance growth rate was derived and phenomenologically analyzed. The transverse and longitudinal components in the horizontal beam size were separated by making use of their different evolution behaviors. The quadrupole mode beam size oscillation after transition crossing is also studied and explained. We found a considerable space-charge-induced emittance growth rate component in the vertical plane but not as much for the horizontal plane. We carried out multiparticle simulations to understand the mechanism of space-charge-induced emittance growth. The major sources of emittance growth were found to be the random skew-quadrupole and dipole field errors in the presence of large space-charge tune spread.
PRSTAB 9, 014202 (2006)
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Slides
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