Influence of Superconducting Cable Dimensions on Field Harmonics in the LHC Main Dipole

The quality of the magnetic field in the LHC main dipoles is given by the correct location and dimensions of the superconducting cables. In this paper the measurements of the dimensions of the LHC cables are presented; then the impact on field quality due to the tolerances on cable dimension is analyzed showing that biggest effect is found on even skew field harmonics. A Monte Carlo study is performed: the effect on random components of the field harmonics is studied and the impact on field quality of the coupling of two different cable producers in the same aperture is evaluated. We finally present a study of the correlation, based on the ninety pre-series collared coils, between cable geometry and field measurements.