RF Manipulations for Special LHC-Type Beams in the CERN PS

Beams with special longitudinal characteristics for the Large Hadron Collider (LHC) have been produced in the Proton Synchrotron (PS) and CERN. The flexibility of its RF systems consisting of in total 25 RF cavities at frequencies from 400 kHz to 200 MHz allows a variety of longitudinal beam manipulations. In particular the main RF system is split into three independent groups tunable from 2.8 MHz to 10 MHz. It is used to merge, split and change the spacing between bunches by applying different voltage and phase programs to the three groups of cavities at different harmonic numbers simultaneously. The batch compression, merging and splitting (BCMS) process has been operationally used for LHC fillings since 2016. To mitigate issues with long bunch trains in the LHC in 2017, short gaps of four bunch positions have been introduced between mini-batches of eight bunches (8b4e). A higher brightness version resulting in four mini-batches per PS extraction has been delivered for luminosity production in the LHC. This paper summarizes the operational experience and indicates possible future RF manipulation schemes.