Author: Porcelli, T.
Paper Title Page
WEPPD015 Saturation Behaviour of the LHC NEG Coated Beam Pipes 2525
  • G. Bregliozzi, V. Baglin, J.M. Jimenez, G. Lanza, T. Porcelli
    CERN, Geneva, Switzerland
  In the CERN Large Hadron Collider (LHC), about 6 km of the UHV beam pipe are at room temperature and serve as experimental or utility insertions. TiZrV non-evaporable getter (NEG) coating is used to maintain the design pressure during beam operation. Molecular desorption due to dynamic effects is stimulated during protons operation at high intensity. This phenomenon produces an important gas load from the vacuum chamber walls which could lead to a partial or total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG re-activation, it is necessary to take in account all these aspects and to regularly evaluate the saturation level of the NEG coating. Experimental studies in a typical LHC vacuum sector were conducted in order to identify the best method to assess the saturation level of the beam pipe. Partial saturation of the NEG was performed and the effects in the variations of pressure reading, effective pumping speed, transmission and capture probability are analysed. Finally, based on these results, a detailed analysis of the NEG coating saturation level of some area of the LHC is presented and analysed.