Magnetization Measurements of$rm Nb_3rm Sn$Wires for the Next European Dipole (NED)

摘要

The Next European Dipole (NED) activity is developing a high-performance$ Nb_3 Sn$wire (aiming at a noncopper critical current density of 1500$ A/mm^2$at 4.2 K and 15 T), within the framework of the Coordinated Accelerator Research in Europe (CARE) project. As part of the conductor development program, magnetization measurements are carried out in parallel and transverse field, from low fields up to 10 T to characterize the conductor. Three Italian facilities are involved: INFN-Frascati, INFM-CNR Genova and INFN-Genova. In particular, measurements at low fields were performed to study magnetic instabilities (flux jumps) in strands with high critical current density. Experimental results, showing a correlation between instabilities at low fields and the residual unreacted niobium, are presented.