Training of the Main Dipoles Magnets in the Large Hadron Collider Toward 7 TeV Operation

During 2016, one-quarter of the LHC main dipoles have has been powered above the 7.7 T operational field, to reach a field of 8.1 T. These tests were done to confirm the extrapolation of the training behavior based on a Gaussian tail of the quench distribution. In this paper, it is shown that a modified Gaussian distribution can be used to better model the quench distributions. We then present the data above 6.5 TeV, showing that they are compatible with the previous expectations. We present the data of retraining of sector 12, which was warmed up in 2016 to replace a magnet, and training of individual magnets that went through several thermal cycles: there is an indication that training campaigns during successive warm-ups and cool-downs could become shorter. We finally show that a significant correlation is found between the training of the installed magnet and individual test after a thermal cycle (second cool-down). On the other hand, no correlation is found with individual test under virgin conditions (first cool-down).