Interaction of intrabeam scattering, longitudinal wakefield and a passive harmonic rf cavity in SOLEIL II

Abstract Synchrotron light sources worldwide are transforming into next-generation facilities with ultra-low transverse emittances at the diffraction limits. With these parameters, intrabeam scattering (IBS) becomes significant and can spoil the light quality by increasing the natural emittance and energy spread. A harmonic cavity can be installed to mitigate this effect by increasing the bunch length. Another way to reduce the impact of IBS is to operate with the full transverse coupling. This contribution considers the IBS effect on SOLEIL II performance with an up-to-date impedance model, a passive harmonic cavity, different insertion device gap configurations (open, closed), and full transverse coupling for two main foreseen operation modes. The combined effect of IBS and microwave instability (MWI) on the energy spread is reported. It is demonstrated that the contribution of IBS to energy spread increase is as significant as that of MWI for SOLEIL II.