Analysis of Nb$_{3}$Sn Rutherford cable production and strand deformations

The development of cutting-edge 11-12 T superconducting magnets made from Nb$_{3}$Sn technology is one of the major milestones for the upgrade of the Large Hadron Collider at CERN. The upgrade, called High Luminosity LHC Project, was planned in order to reach higher luminosity and discover new particles. Replacing the NbTi superconductor with the Nb$_{3}$Sn makes it possible to reach a practical operating magnetic field limit of up to 16 T. The superconducting coils are formed by Nb$_{3}$Sn Rutherford cables with a trapezoidal cross section and composed of 40 strands. Since the superconducting phase of Nb$_{3}$Sn is very brittle and it is reached after a thermal cycle, the Nb$_{3}$Sn Rutherford cable needs to be wound in a coil before the thermal treatment. The cabling process is a delicate step in the production of high performing cables that need different systems to control their quality. This work aims to provide practical tools to analyze the Nb$_{3}$Sn Rutherford cable production and the strands deformations due to the high aspect ratio of the Rutherford cable. Thanks to these tools it was possible to monitor the fluctuations of the mechanical tensions of the strands during cabling, localize the manufacturing defects and find the critical mechanical distortions inside the strands which cause degradation in the electrical performances. The results of the fluctuations in mechanical tensions are compared to the size variation of the lateral facets of the cable and the data related to the number of critical deformations are compared to the degradation of the electrical performances; the comparisons were performed in order to investigate a possible specific correlation. However, further measurements are foreseen to confirm the results.