Niobium-tin (Nb3Sn) could eventually replace niobium-titanium (NbTi) as a superconducting material in the coils that make up the magnets of particle accelerators. However, it requires multiple manufacturing steps and is very fragile after its shaping.
The Irfu, in collaboration with CERN, has embarked on an ambitious program to develop Nb3Sn magnets capable of producing a magnetic field of 16 teslas (as opposed to the LHC's 8 teslas), for use in future particle accelerators.
In order to test new technologies and new manufacturing processes in conditions representative of future high-field magnets, CERN, in collaboration with Irfu, has developed a 50-cm long test coil model called SMC, or Short Model Coil.
Between May and October 2021, Irfu entirely manufactured an SMC coil in Nb3Sn and delivered it to CERN. It was subsequently assembled at CERN in a structure, and then tested in June 2022 in a superfluid and liquid helium bath, under strong current, in a specialized facility.
The coil reached 85% of its maximum current in superfluid helium at 1.9 kelvins, generating a 12-tesla field. It then reached 95% of its maximum current in liquid helium at 4.2 kelvins, without any observed degradation of the superconductor.
These successes validate the manufacturing processes of the Nb3Sn coil. The next phase has already begun: the fabrication of a superconducting Nb3Sn dipole (R2D2 magnet), also entirely produced at the Irfu, using an innovative technology. The objective is to produce very high magnetic fields in highly compact coils for the particle accelerators of tomorrow.