Common coil magnet program at BNL

The goal of the common coil magnet R&D program at Brookhaven National Laboratory (BNL) is to develop a 12.5 T, 40 mm aperture dipole magnet using “react and wind technology” with high temperature superconductors (HTS) playing a major role. Due to its “conductor friendly” nature, the common coil design is attractive for building high field 2-in-1 dipoles with brittle materials such as HTS and Nb₃Sn. At the current rate of development, it is expected that a sufficient amount of HTS with the required performance would be available in a few years for building a short magnet. In the interim, the first generation dipoles will be built with Nb₃Sn superconductor. They will use a “react and wind” technology similar to that used in HTS and will produce a 12.5 T central field in a 40 mm aperture. The Nb₃Sn coils and support structure of this magnet will become a part of the next generation hybrid magnet with inner coils made of HTS. To develop various aspects of the technology in a scientific and experimental manner, a 10-turn coil program has been started in parallel. The program allows a number of concepts to be evaluated with a rapid throughput in a cost-effective way. Three 10-turn Nb₃Sn coils have been built and one HTS coil is under construction. The initial test results of this “react and wind” 10-turn coil program are presented. It is also shown that a common coil magnet design can produce a field quality that is as good as a conventional cosine theta design