Field quality study of a 1-m-long single-aperture 11-T Nb3Sn dipole model for LHC upgrades

FNAL and CERN are carrying out a joint R&D program with the goal of building a 5.5-m-long twin-aperture 11-T Nb3Sn dipole prototype that is suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture and twin-aperture dipole models with a nominal field of 11 T at the LHC operation current of 11.85 kA and 20% margin. This paper presents the results of magnetic measurements of a 1-m-long single-aperture Nb3Sn dipole model fabricated and tested recently at FNAL, including geometrical field harmonics and effects of coil magnetization and iron yoke saturation.