Field-shape Imperfections of the Cern-lhc Dipole Arising from Mechanical Deformations and Component Tolerances

The stability of the geometry of the superconducting coils is essential to the field homogeneity of the LHC dipole magnets. Mechanical stresses during coil assembly, thermal stresses during cool-down and electromagnetic stresses during operation are the sources of deformations of the coil geometry. Additional sources of field-shape errors are the dimensional tolerances of the magnet components and of the manifacturing and assembling tooling. To provide a realistic evaluation of the field-shape imperfections of the LHC dipoles arising from the above effects, appropriate finite-element computations were carried out to model the dipole cross-section in presence of stresses and a preliminary insight of the effect of the manifacturing tolerances was achieved as well.