Possible Reuse of the LHC as a 3.3 TeV High Energy Booster for Hadron Injection into the FCC-hh

One option for the injector into a 100 TeV centre-of-mass energy frontier proton collider (FCC-hh) in a new tunnel of 80–100 km circumference is to reuse a suitably modified LHC as 3.3 TeV High Energy Booster (HEB). The changes that would be required to the existing LHC insertions are described, including the types and numbers of new magnets and circuits. The limitations on the maximum LHC ramp rate and minimum cycle time discussed. The key question of the minimum FCC filling time achievable with technically possible upgrades is examined, together with the issues of decommissioning for the elements which would need to be removed from the machine. The potential performance reach of the modified LHC as 3.3 TeV HEB is quantified, and implications for FCC-hh discussed.