Manufacturing and Testing of the First Nb3Sn Subscale Stress-Managed Common-Coils: 2-in-1 Dipole Magnet Developed at the Paul Scherrer Institute

The magnet development (MagDev) laboratory at the Paul Scherrer Institute (PSI) has designed the subscale stress-managed common-coils (subSMCC1) 2-in-1 dipole magnet as part of the CHART (Swiss Accelerator Research and Technology) contribution to the CERN HFM (High-Field Magnet) programme. This R&D vehicle is part of the CHART/MagDev high-field roadmap. The nature of the subscale magnet allows it to be manufactured and tested quickly, so lessons learned from it will be applied to the high-field stress-managed common-coils demonstrator that is currently under development. The magnet has a straight section of 150 mm, two clear bore apertures of 22 mm, and an inter-beam spacing of 120 mm. In the first version, the magnet structure consists mainly of inner and outer pads surrounding the straight sections of the coil, and inner and outer pads at the coil ends, with no iron yoke or shell. Axial pre-load is provided by six rods connected to the end pads. All structural components, including the split-former pieces, are made from the same stainless-steel alloy. The first magnet, with four stress-managed Nb₃Sn common-coils, was manufactured and tested. This contribution presents the detailed manufacturing process as well as test results, training behavior and mechanical measurements.