Beam-Based Kicker Waveform Measurements Using Long Bunches

The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1. KFA10, BT4. KFA10 and BT2. KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness.