Quench Protection Study of the Eurocircol 16 T cosθ Dipole for the Future Circular Collider (FCC)

After LHC will be turned off, a new, more energetic machine will be needed in order to explore unknown regions of the high-energy physics. For this reason, the project Future Circular Collider (FCC) has started, with the goal of developing a 100 km circumference collider of 50 TeV proton beams. The Eurocircol collaboration is part of the FCC study under the European Community leadership, and it aims to develop a conceptual design of FCC within 2019. One of the main targets is to design a bending dipole able to reach 16 T operation magnetic field, in order to accomplish the size and energy constraints. Such a magnetic field can be reached using Nb$_{3}$Sn conductors at their highest performance. One option under exploration is the Cosθ dipole, by INFN of Milano and Genova. One of the aspects to be taken into consideration is the amount of conductor needed, because of the relatively high cost of superconducting cables involving Nb$_{3}$Sn. The amount of superconductor in the cross-section conductor area is a discriminant element for the choice of the magnet lay-out. At the same time enough copper stabilizer must be included in order to limit the Joule dissipation in case of quench. For these reasons, together with the very high stored energy, quench protection is one of the most challenging aspects of the design. In this paper, the quench protection of the cosθ design is presented. A standard quench protection study is accompanied by a less conservative study which includes AC effects on the power dissipation inside the coils and on the magnet inductance, in order to not exclude preventively more convenient designs, and to develop a more performing magnet as possible