Simulations and Measurements of Longitudinal Coupled-bunch Instabilities in the CERN PS

Among various and challenging objectives of the LHC Injectors Upgrade project (LIU), one aim is to double the beam intensity of the CERN Proton Synchrotron (PS) in order to achieve the integrated luminosity target of the High-Luminosity LHC project (HL-LHC). A known limitation to reach the required high intensity is caused by the longitudinal coupled-bunch oscillations developing above the transition energy. The unwanted oscillations induce large bunch-to-bunch intensity variations not compatible with the specifications of the future LHC-type beams. A wide-band longitudinal damper has been installed in the PS to suppress these instabilities and is going to be commissioned. A measurement campaign of coupled-bunch oscillations has been launched to substantiate the extrapolations and predictions for the future High Luminosity LHC beam with the final aim to determine the maximum intensity that could be provided to the LHC. In parallel a Simulink© model of the PS is going to be implemented to predict the machine behavior in the parameter space of LIU and to be used during the beam commissioning and optimization of the feedback system.