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Boine-Frankenheim, O.

Paper Title Page
THPAN018 Stability Thresholds for Transverse Dipole Modes with Nonlinear Space Charge, Chromaticity and Octupoles 3262
 
  • V. Kornilov, O. Boine-Frankenheim, I. Hofmann
    GSI, Darmstadt
  
  Funding: Work supported by EU design study (contract 515873 -DIRACsecondary-Beams)

Transverse stability due to combinations of chromaticity effect, nonlinear space charge and octupoles of different polarities plays an important role in the determination of the impedance budget for the FAIR synchrotrons. Different analytic approaches [*,**,etc.] have been suggested, for which no direct comparison has been made so far. In order to clarify this issue we perform numerical investigations employing the particle tracking code PATRIC and compare results of simulation scans with predictions of a dispersion relation. Space charge effects within self-consistent and 'frozen' models are used for comparisons, connection to beam transfer function studies is addressed.

* D. Moehl, CERN/PS 95-08 (DI), (1995)** M. Blaskiewicz, Phys. Rev. ST Accel. Beams 4, 044202, (2001)

 
FRPMN014 3D Simulation of Coherent Instabilities in Long Bunches Induced by the Kicker Impedances in the FAIR Synchrotrons 3919
 
  • O. Boine-Frankenheim, V. Kornilov
    GSI, Darmstadt
  
  Funding: Work supported by the European Community under the FP6 programme: Structuring the European Research Area - Specific Support Action - DESIGN STUDY (contract 515873 - DIRACsecondary-Beams).

3D simulation studies of the transverse impedance budget for long bunches in the FAIR synchrotrons have been started. Important transverse instability driving sources are the thin resistive wall and the kicker impedances. Major concerns are the required low momentum spreads and the additional loss of Landau damping due to the space charge tune shift. The simulation code PATRIC has been extended in order to predict coherent instability thresholds with space charge and for broadband impedance sources. Examples of code benchmarking using the numerical Schottky noise, analytical stability boundaries and comparisons with other codes will be discussed. The improvement of transverse stability in long bunches relative to a coasting beam is analyzed for different rf wave forms. Conclusions for the impedance budget in the FAIR synchrotrons are drawn.