Analysis of Geometry and Field Quality Along the Series Production of the 11 T Dipole for the High Luminosity LHC

The first series production of Nb3Sn Accelerator Magnets is approaching its end. The LHC dipole upgrade within the scope of the High Luminosity project consists of collared assemblies of 5.6 m-long coils targeted for a nominal field of 11 T at 11.85 kA and 60 mm aperture. As part of the quality control of the production, geometrical and magnetic measurements are performed at different steps. The experience gathered during manufacturing of 28 coils and 11 collared coils is summarized here. Using the available data, we analyzed the distributions of coil geometry, collared coil size, main field, and low order field errors in warm conditions. In some cases, the trends were traced back to displacements of the conductor with respect to the nominal layout. Three magneto-static conductor deformation models aim to explain the variability of field harmonics, confronted with measured data.