Assessment of the operation safety margin of the HL-LHC superconducting recombination Dipole D2 in case of helium filling failure

Abstract After the successful completion of cryogenic performance tests He II heat exchanger prototype for D2 recombination dipole future HL-LHC project at CERN, specific measurements were performed to determine operation safety margin in case abnormal operating conditions. This is particularly relevant failure liquid helium supply cold source. For nominal operation, level regulated a constant value and it not necessary know its very accurately. However, partial drying due discontinuation supply, essential monitor absolute anticipate any cooling malfunction. paper describes procedure an accurate in-situ measurement as well loss mass flow rate estimates phase separator. The margins magnet are then analyzed different conditions considered during runs non-nominal