Overview of HTS Accelerator Magnet Developments at CEA Saclay

CEA Saclay is working since 2008 on High Temperature Superconductor (HTS) developments for accelerator magnet application. Two dipole models were realized at CEA Saclay: the EuCARD block dipole magnet and the EuCARD2 cosine-theta dipole magnet. The EuCARD block dipole magnet, relying on 12-mm REBCO tapes, was the first step to demonstrate the potential of REBCO type HTS ceramic tapes to generate 5-T field. The magnet manufacturing was completed in 2016, and the magnet cold tests performed at CEA in 2017. Magnet design and manufacturing process, as well as first cold tests of the magnet have already been presented in 2018. Since then, additional cold tests have been carried out up to the nominal current and beyond, reaching a record induction field of 5.37 T without quench. The EuCARD2 cosine-theta dipole magnet, relying on REBCO HTS Roebel cable, aimed also to produce a central 5-T dipole field, but with an accelerator-type dipole design and accelerator magnet field quality. The detailed design and coil manufacturing process have already been presented in 2019. Between 2019 and 2020, three coils were built, with a SuperOx tape based Roebel cable. In 2021, the magnet has been assembled, at CEA Saclay, with the last two produced coils, and in 2022 it has been cold tested at CERN in self field configuration. Despite the degraded performance of one of the coils, directly linked to an overheating problem during its production, the cold tests made it possible to highlight the good potential of the cos-theta design with Roebel cable.