IPAC2013 - List of Authors (Porcelli, T.)

Paper	Title	Page
THPFI049	Evaluation of the NEG Coating Saturation Level after 3 Years of LHC Beam Operation	3397
	G. Bregliozzi, V. Baglin, J.M. Jimenez, G. Lanza, T. Porcelli CERN, Geneva, Switzerland
	The room temperature vacuum system of the Large Hadron Collider (LHC) at CERN system has been designed to ensure vacuum stability and beam lifetime of 100 h with nominal current of 0.56 A per beam at 7 TeV of energy. During last two years the LHC operated with proton beams at a maximum energy of 4 TeV, coasting for several hours each time, inducing high pressure due to different effects: synchrotron radiation, electron cloud and localized temperature increase. All these phenomena generated an important gas load from the vacuum chamber walls, which led in some cases to a partial or a total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG vacuum reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. This study analyses the saturation level of the NEG coated beam pipes in the LHC accelerator. Pressure reading variation without proton beams circulating are analysed and combined with laboratory studies of the NEG saturation behaviour and with Vacuum Stability Code (VASCO) simulations.

Paper

Title

Page

Evaluation of the NEG Coating Saturation Level after 3 Years of LHC Beam Operation

3397

G. Bregliozzi, V. Baglin, J.M. Jimenez, G. Lanza, T. Porcelli
CERN, Geneva, Switzerland

The room temperature vacuum system of the Large Hadron Collider (LHC) at CERN system has been designed to ensure vacuum stability and beam lifetime of 100 h with nominal current of 0.56 A per beam at 7 TeV of energy. During last two years the LHC operated with proton beams at a maximum energy of 4 TeV, coasting for several hours each time, inducing high pressure due to different effects: synchrotron radiation, electron cloud and localized temperature increase. All these phenomena generated an important gas load from the vacuum chamber walls, which led in some cases to a partial or a total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG vacuum reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. This study analyses the saturation level of the NEG coated beam pipes in the LHC accelerator. Pressure reading variation without proton beams circulating are analysed and combined with laboratory studies of the NEG saturation behaviour and with Vacuum Stability Code (VASCO) simulations.