  During its Run 2 (2015-2018), the Large Hadron Collider (LHC) operated at
almost twice higher energy, and provided Pb-Pb collisions with an order of
magnitude higher luminosity, than in the previous Run 1. In consequence, the
power of the secondary beams emitted from the interaction points by the
bound-free pair production (BFPP) process increased by a factor ~20, while the
propensity of the bending magnets to quench increased with the higher magnetic
field. This beam power is about 35 times greater than that contained in the
luminosity debris from hadronic interactions and is focused on specific
locations that fall naturally inside superconducting magnets. The risk of
quenching these magnets has long been recognized as severe and there are
operational limitations due to the dynamic heat load that must be evacuated by
the cryogenic system. High-luminosity operation was nevertheless possible
thanks to orbit bumps that were introduced in the dispersion suppressors around
the ATLAS and CMS experiments to prevent quenches by displacing and spreading
out these beam losses. Further, in 2015, the BFPP beams were manipulated to
induce a controlled quench, thus providing the first direct measurement of the
steady-state quench level of an LHC dipole magnet. The same experiment
demonstrated the need for new collimators that are being installed around the
ALICE experiment to intercept the secondary beams in the future. This paper
discusses the experience with BFPP at luminosities very close to the future
High Luminosity LHC (HL-LHC) target, gives results on the risk reduction by
orbit bumps and presents a detailed analysis of the controlled quench
experiment.
