Design and considerations on long Nb3Sn high field magnets for hadron colliders

Design studies for long high field Nb₃Sn superconducting magnets for hadron colliders are described, taking a 10 meter magnet with a cosine-theta type coil as an example. The problems and complications are discussed in comparison with short magnets of 1 meter length, using MIIT calculations and quench simulation. As the stored energy in the high field Nb₃Sn magnets is quite large, close attention must be paid to all design details, and especially the extraction of the stored energy. The extensive use of heaters on the coil surface is simulated to dump the energy on the coil body itself. The MIIT value of the Nb₃Sn superconducting cable should be made large for safe operation. This is done by increasing the copper ratio. According to the results of this study, an 11.5 Tesla magnet might be the limiting case for the design of a practical accelerator high field magnet