Study of the protection system for Nb3Sn "slot" design NED dipole

The Next European Dipole (NED) Collaboration has the scope to promote the study and development of a high magnetic field (about 15 T on the conductor) and large aperture dipole magnet aimed at LHC upgrade and at the next generation colliders. Among different configurations, a novel solution has been considered. This magnet will be based on a high current density Nb3Sn superconductor (Jc around 1500 A/mm(2) @ 15 T, 4.2 K in the non-copper section), and will have a large stored magnetic energy (4.0 MJ/m, i.e. 18 times higher than for one LHC dipole), that makes the magnet protection extremely critical. In this paper we have investigated the quench propagation assuming different dump resistance values and operating conditions (quench heaters efficiency, delay time for the Quench Detection System), in order to optimize the protection system in terms of peak temperatures in the coils and maximum voltage drops. The study has been performed by using the quench propagation code QLASA, which has been developed at LASA Lab, Milan.