Speaker
Description
CEA Paris-Saclay is developing, in collaboration with CERN, the R2D2 (Research Racetrack Dipole Demonstrator) magnet. The main goal is to demonstrate the feasibility of key technologies for future high field 16 T $Nb_3Sn$ magnets for particle colliders. On one hand, the coil manufacturing has been finalized and four coils have been produced. First, two practice coils have been manufactured, following all the steps representative of a real coil (winding, heat treatment, impregnation, instrumentation, electrical tests and geometrical measurements). One coil used Cu dummy cables and allowed to validate the infrastructure, the tooling and the manufacturing procedures. Another coil used the $Nb_3Sn$ nominal cables and allowed quantifying the behavior during the reaction of $Nb_3Sn$ conductors. The dilatations and contractions observed were compared and validated with measurements on cable-stacks and subscale coils. The practice coils have been cut for analysis and to validate the quality of the manufacturing. In addition, two $Nb_3Sn$ series coils have been manufactured, and are ready for an assembly in the mechanical structure. In parallel, the mechanical structure has been procured, and a first assembly has been performed using an Al dummy coil block. The structure followed a procedure similar to the final magnet assembly: the magnet has been pre-loaded to the final target, and then cooled-down in liquid nitrogen to simulate the cool-down in liquid helium. During these loading steps, the stresses have been monitored using strain gauges mounted on the structure and on the Al dummy coil block, and compared with the Finite-Elements models. This allowed the validation of the mechanical behavior of the structure in representative conditions. The magnet is now ready to be assembled with two $Nb_3Sn$ coils for a first performance test in liquid helium at CERN. An overall update of the project status will be given, and the next steps will be presented.
