CERN, Geneva
The LHC magnet system has been largely commissioned in 2007-08: all sectors up to 7 kA (4 TeV proton beam energy); six (out of eight) sectors were commissioned up 9.3 kA (5.5 TeV) and one to 11.5 kA (6.9 TeV). For more than one week, both beams have been injected, circulated and captured in the RF bucket, thus assessing the optics at injection energy. The incident in sector 3-4, originated by a serious defect of a high-current joint between magnets with large collateral damage, has changed the plans: magnets in the damaged zone (about 50) are being substituted or repaired meanwhile a campaign of consolidation is under way. During commissioning, the training of the main dipoles was longer than expected on the basis of reception tests of individual magnets , thus pointing to a partial loss of quench memory. The thermal performance is within heat losses estimates and the spectacular easiness of the first injection test on 10th September has demonstrated the very good field quality, precise understanding of magnetic characteristics, quality of the elaborate field modeling and the very good shape of the magnets with proper alignment of the machine.
