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Quench Protection Studies of the 11-T Nb3Sn Dipole for the LHC Upgrade

The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas. Fermilab and CERN are developing an 11-T Nb3Sn dipole to replace some 8.33-T 15-m-long Nb-Ti LHC main dipoles providing longitudinal space for the collimators. In case of a quench, the large stored energy and the low copper stabilizer fraction make the protection of the 11-T Nb3Sn dipoles challenging. This paper presents the results of quench protection analysis, including quench protection heater design and efficiency, quench propagation, and coil heating. The numerical results are compared with the experimental data from the 2-m-long Nb3Sn dipole models. The validated model is used to predict the current decay and hot spot temperature under operating conditions in the LHC, and the presently foreseen magnet protection scheme is discussed.