Upgrades of the RF Systems in the LHC Injector Complex

In the framework of the LHC Injector Upgrade (LIU) project the radio-frequency (RF) systems of the synchrotrons in the LHC injector chain will undergo significant improvements to reach the high beam intensity and quality required by the High-Luminosity (HL) LHC. Following the recent upgrade of the longitudinal beam control system in the PS Booster (PSB), tests with Finemet cavities are being performed in view of a complete replacement of the existing RF systems in the PSB by ones based on this technology. In the PS a similar wide-band Finemet cavity has been installed as a longitudinal damper. New 1-turn delay feedbacks on the main accelerating cavities to reduce their impedance have also been commissioned. Additional feedback and beam control improvements are foreseen. A major upgrade of the main RF system in the SPS by regrouping sections of its travelling wave cavities, increasing the number of cavities from four to six, will reduce beam-loading and allow higher intensities to be accelerated. The upgrade includes the installation of two new RF power plants and new feedback systems. All upgrades will be evaluated with respect to their expected benefits for the beams to the LHC.