Speaker
Description
Impedance-driven head-tail instabilities in circular colliders such as the Large Hadron Collider (LHC) are typically suppressed by the introduction of Landau damping induced with strong external nonlinearities. However, it has been shown that sufficiently strong direct space charge can also serve to mitigate these instabilities, with previous simulations [Oeftiger 2017] indicating that stability of single-bunch operation may be achieved for certain intensities in the LHC without the introduction of external nonlinearities. The effect of space charge on Landau damping was explored quantitatively in [Macridin 2015]. This work builds upon the previous simulation studies of the LHC to characterise the strength of space-charge and nonlinearity-induced Landau damping across the parameter space, comparing the results to those predicted by the formulae of Macridin et al. The characterisation of the additional Landau damping from space charge may inform the intentional reduction of octupole currents in these regimes, or provide additional margin for the suppression of e-cloud-derived instabilities.