Test results of ISSAAC, a 12 T demonstrator of low preload common coil

During the last months, the assembly of  ISAAC demonstrator was completed at CERN through a close collaboration between the CERN and CIEMAT teams.ISAAC stands for Investigating Superconducting Assembly to Address Common Coil mechanics: this magnet, developed at CIEMAT, reuses two coils made for the RMC program and tested in 2019, assembling them in a common coil structure based a on very low preload. Concepts were developed in the past years, aiming at 12 T  with 20% margin and a 34 mm double aperture as presented at MT and ASC (1,2) in 2023 and 2024. 

The magnet was tested at CERN in September, starting with a first quench at 13.0 T bore field, i.e 93% of short sample limit (1.9 K). The magnet did not train further, reaching 13.1 T after few quenches. An holding current of 16 h was performed successfully at 13.0 T (one T above nominal). Mechanical instrumentation data acquisition and magnetic measurements were performed.

The test results will be presented by the SM18 team in the coming weeks at the HFM forum and were shortly outlined by Carla Martins at ASC conference last week. This is the first common coil based on Nb3Sn built at CERN on a conceptual and engineering design made by CIEMAT: 13 T is a good start! This confirms the interest of this design, and the success of the CERN/CIEMAT collaboration.

J. Garcia Matos, et al., “Design of a Common Coil Magnet using Existing Racetrack Model Coils (RMC),” IEEE Trans. Appl. Supercond. 34 (2024) 4300105  
C. Martins Jardim, et al., “Mechanical Design of a Common Coil Magnet With RMC Coils (ISAAC),” IEEE Trans. Appl. Supercond. 35 (2025) 4002705