Electron Cloud: Observations with LHC-Type Beams in the SPS

In August 1999, strong pressure increases were observed in the SPS in the presence of the new LHC-type beams. This paper reports on observations of the electron cloud phenomenon and the related pressure increase as a function of parameters such as the number of protons per bunch, the number of bunches per batch, the shape of the vacuum chamber and the electron current collected on pick-ups. Results of the observed clean-up, "beam scrubbing" will be presented as well as the consequences of the e-cloud phenomenon on the SPS operation with the LHC nominal beam intensity

Electron Cloud Effects in the CERN SPS and LHC

Electron cloud effects have been recently observed in the CERN SPS in the presence of LHC type proton beams with 25 ns bunch spacing. Above a threshold intensity of about 4 X 10^12 protons in 81 consecutive bunches, corresponding to half of the nomina