Upgrading the Fast Extractions Kicker System in SPS LSS6

A fast extraction system, located in the LSS6 region of the CERN SPS accelerator, transfers 450 GeV/c protons, as well as ions, via the TI 2 transfer line towards the LHC. The system includes three travelling wave kicker magnets, all powered in series, energised by a single Pulse Forming Network (PFN) and terminated by a short circuit. The specification for the system requires a kick flattop of $7.8 \mu$s with a ripple of not more than ±0.5%. Recent measurements with beam show that the ±0.5% kick specification is achieved over $7.1 \mu$s of the kick flattop; however the ripple over $7.8 \mu$s is ±0.75%. Initial electrical measurements have been carried out on each of the three magnets; more detailed comparisons of the beam measurements and the contribution of each magnet to the detailed shape of the flattop kick will be carried out. This paper reports the results of initial measurements and plans for future measurements to permit modifications to the PFN for reducing flattop ripple.