Electromagnetic design of a 12 T twin-aperture dipole magnet

A 12 T twin-aperture subscale magnet is under development at the Institute of High Energy Physics (IHEP, Beijing, China), as the R&D of high-field accelerator magnet technology for SPPC (Super Proton–Proton Collider) pre-study. Four NbTi coils and two Nb3Sn coils will be fabricated firstly, to provide a 12 T dipole field in two apertures with the load line ratio of 20% at 4.2 K. After that, the HTS (ReBCO and Bi-2212) coils will be inserted between the Nb3Sn coils to realize a higher dipole field. The ReBCO coils with the block-type configuration will be inserted between the Nb3Sn coils with common-coil configuration (Combined Common-coil and Block type configuration, CCB), to make the broad plane of the tape parallel with the magnetic flux and maximize current-carrying capacity. The electromagnetic design, mechanical design and quench protection design have been completed. The fabrication is ongoing. The magnet will be assembled and tested in 2017.