LHC cryogenics – Run2 (2015) summary and perspectives

After LS1 the LHC cryogenic installation was progressively restarted from May 2014. Cool down, multiple tests and qualifications of the machine components lasts for 10 months. The LHC cryogenic system with new validated scenario came back to operation for period of Run2 on 5 th April 2015. Run2 (2015) is considered as a successful year. The global availability indicated by Cryo Maintain (CM) interlock reached level of 92.1%. Helium yearly consumption was again decreased. Consolidations and repairs applied on different systems of the cryogenic installation were effective. Main difficulty during last year operation was related to heat load coming from activated electron cloud. In some cases related heat deposition on the beam screen circuit was nearly twice higher than values assumed for the LHC design and cryogenic system was pushed to the limits of its capacity. Last year operation period was affected with one major failure on 4.5 K cryogenic refrigerator at P8 and a few other small failures linked mainly to operational usage of different components. The spares strategy for critical parts allowed for transparent to operation replacement of these components. The proposed operation scenario for Run2 (2016) is similar to one used in 2015 with potential for optimisation on P18/P2 cryogenic plants.