Abstract
We describe a dedicated electron cloud experiment which was installed in the CERN Proton Synchrotron in 2007. The setup comprises shielded button-type pickups, a fast vacuum logging, a dipole magnet, and a stripline electrode to experimentally verify the beneficial effect of electron cloud clearing. The electron cloud effect was observed within the last milliseconds before ejection of the nominal LHC proton beam consisting of 72 bunches with 25 ns spacing. Measurements of electron flux at the wall and vacuum pressure are presented for a set of magnetic fields and bias voltages on the clearing electrode, showing that efficient electron cloud suppression can be obtained for appropriate clearing voltages but revealing an unexpectedly complex dependence on magnetic field and voltage.
Highlights
IntroductionIn the CERN Proton Synchrotron (PS) electron cloud (EC) effects have been observed in 2000 with the first production of high intensity LHC beam [6]
Since its first observation at the Budker Institute of Nuclear Physics Proton Storage Ring, the electron cloud (EC) effect has been discovered at many high intensity particle accelerators, including the CERN Intersecting Storage Rings, the Stanford Linear Accelerator Center PEP-II, the CERN Super Proton Synchrotron (SPS), and the KEK B Factory [1,2,3,4,5]
Starting from June 2007 clear signs of an electron cloud were found in the PS with nominal LHC beam
Summary
In the CERN Proton Synchrotron (PS) EC effects have been observed in 2000 with the first production of high intensity LHC beam [6]. For the current production scheme of the nominal LHC beam no electron cloud related instabilities are observed, but it is not excluded that such instabilities may occur for higher proton intensities [7]. For this reason it was desirable to have a dedicated EC diagnostics in the PS, which is the subject of this paper. By tuning the beam parameters the EC can be reduced This method has the drawback that the accelerator performance may be negatively affected. In some cases machine operation in presence of an EC can be handled by damping the induced instabilities
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