Title :
The SPS as a vacuum test bench for the electron cloud studies with LHC type beams
Author :
Arduini, G. ; Jimenez, J.M. ; Weiss, K.
Author_Institution :
CERN, Geneva, Switzerland
Abstract :
The SPS machine has been operating with LHC-type beams with bunch intensities up to 8×1010 protons (70% of LHC nominal intensity). This paper will give evidence of the electron cloud phenomenon as the mechanism responsible for the pressure rises in the SPS in presence of LHC type beams. The dependence of the pressure rise and of the electron current measured with dedicated pickups on various beam characteristics such as proton bunch intensity, number of bunches needed to start the e-cloud phenomenon and the effect of missing bunches will be presented. The evolution of the pressure rise with the integrated current (´beam scrubbing´) will be discussed. The observed effect of the dipole magnetic field and of the treatment of the stainless steel vacuum chambers with N2 glow discharge on the pressure rise and on its evolution with the integrated current will be also considered. Finally, the consequences of the electron cloud build-up on the SPS vacuum system for the LHC beam nominal intensity will be described
Keywords :
accelerator magnets; beam handling equipment; electromagnets; particle beam bunching; particle beam diagnostics; particle beam stability; proton accelerators; proton beams; stainless steel; storage rings; synchrotrons; vacuum apparatus; CERN SPS; FeCCr; LHC type beams; N2; beam characteristics; beam scrubbing; bunch intensities; dipole magnetic field; electron clouds; electron current; glow discharge; integrated current; nominal intensity; pressure rises; proton beams; proton bunch intensity; stainless steel vacuum chambers; vacuum test bench; Clouds; Current measurement; Electron beams; Large Hadron Collider; Particle beam measurements; Particle beams; Pressure measurement; Protons; Steel; Testing;
Conference_Titel :
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001
Conference_Location :
Chicago, IL
Print_ISBN :
0-7803-7191-7
DOI :
10.1109/PAC.2001.987605
