Performance of the CERN SPS Fast Extraction for the CNGS Facility

The SPS LSS4 fast extraction system will serve both the anti-clockwise ring of the LHC and the long baseline neutrino (CNGS) facility. For the latter two extractions spaced by 50 ms, each affecting half of the SPS, are foreseen. During the shutdown 2003-2004 the performance of the fast extraction kickers has been improved in order to match more closely the specifications required for the CNGS and LHC extractions. The kick rise and fall times were significantly reduced, as well as the post-pulse kick ripple. However, the latter remained outside specifications and oscillations were induced in the leading bunches of the batch remaining in the machine at the moment of the first extraction. While further improving the kicker pulse shape, the possibility of damping the beam oscillations using the transverse feedback system has been explored. Recent pulse improvements and results of beam tests are reported.