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Description
The use of octupole magnets for Landau damping of transverse instabilities in synchrotrons must be carefully balanced against requirements of the coherent and single-particle stability. The octupoles should provide sufficient damping to suppress the instabilities while fulfilling the dynamic aperture constrains. In beams with a space-charge dominated tune footprint, all these beam dynamics aspects are affected by space-charge. The resonance crossing is driven by space-charge, the instability growth and the properties of Landau damping are modified. Space-charge provides Landau damping of its own in bunches, but can also cause loss of Landau damping. We apply particle tracking simulations including space-charge to study beam losses in the SIS100 synchrotron (FAIR at GSI Darmstadt, Germany), taking into account measured field errors in the main magnets, and the Landau damping octupoles. In parallel, we determine the minimal octupole power required for Landau damping in the presence of space-charge. We identify optimized octupole configurations that minimize beam losses while maintaining beam stability.