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

Design studies for long high field Nb3Sn superconducting magnets far 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 compar ison with short magnets of 1 meter length, using MIIT calculations and quen ch simulation. As the stored energy in the high field Nb3Sn magnets is quit e large, close attention must be paid to all design details, and especially the extraction of the stored energy, The extensive e 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 r esults of this study, an 11.5 Tesla magnet might be the limiting case for t he design of a practical accelerator high field magnet.