One of the main objectives of the Future Circular Collider study is to push the energy frontier of particle colliders in the search for new physics, with the aim of reaching collision energies of at least 100 TeV. This translates in the two technical goals of the High Field Magnet (HFM) R&D:
- Develop conductor and magnet technology towards the ultimate Nb3Sn performance, with the projected upper limit of 16 T dipole field;
- Demonstrate the suitability of High Temperature Superconductors (HTS) and, in particular, of REBCO coated conductors for accelerator magnet applications. HTS would enable high fields beyond the reach of Nb3Sn, in the range of 20 T, and thus a further increase of the collision energy in the next generation hadron colliders.
The WireChar project tackles critical aspects identified as essential to meet these technical goal:
- Establish the mechanical limits at which Nb3Sn superconductors can operate safely and understand the mechanisms behind critical current degradation. Nb3Sn is a brittle intermetallic compound whose superconducting properties are highly sensitive to stress. As a consequence, the degradation of the conductor performance due to the large electromagnetic loads becomes a parameter with a profound impact on the design of accelerator magnets.
- Establish a detailed knowledge of the REBCO critical surface over a large temperature, current and field range. Present day REBCO coated conductors are rapidly evolving materials developed by more than ten different manufacturers, each with their own production process and properties. Because of this versatility and the consequent variability of the performance, a comprehensive characterization of their properties is necessary to assess their readiness for application.
This research activity is part of the CHART initiative and is supported by the European Organization for Nuclear Research (CERN), Memorandum of Understanding for the FCC Study, Addendum FCC-GOV-CC-0176 (KE 4612/ATS).
Since 2015, CHART, which stands for “Swiss Accelerator Research & Technology”, has been bringing together the Swiss leading forces in the R&D of superconductor technology for accelerators under the auspices of the State Secretariat for Education, Research and Innovation (SERI). This interdisciplinary collaboration includes researchers from the Paul Scherrer Institute (PSI), the two Federal Institutes of Technology in Zurich and Lausanne, the University of Geneva and, of course, CERN, and one of its main goals is the design, construction and test of a 16 T dipole prototype.