Impact of the First Powering Cycles on the LHC Superconducting Dipole Coil Geometry

The impact of the first powering cycles on the LHC superconducting dipoles coil geometry has been investigated. Dedicated magnetic measurements have been performed to estimate the changes in the geometric component of the harmonics, caused by the last highest Lorentz force the coil has ever experienced. Several magnets have been powered at increasing current steps while the field quality has been measured to quantify the changes in geometry. The effect of the thermal cycles has been also considered as well as the systematic differences between measurements before and after the quench training. The reconstruction of the coil geometry variations is discussed in terms of continuous modes of deformation as well as single block displacements.