Lawrence Berkeley National Laboratory

Protection against the effects of a quench is a crucial challenge for 16-T-class superconducting dipole magnets for a future 100-TeV Hadron collider. To avoid damage due to overheating of the coil's hot spot, heat generated during the quench has to be homogeneously distributed in the winding pack by quickly and uniformly transferring to the normal-state voluminous coil sections. Conventional protection systems rely on quench heaters placed on the outer surfaces of the coils. However, this technique has to confront significant challenges in order to achieve the fast transitions required by high magnetic field magnets. The recently developed coupling-loss-induced quench (CLIQ) utilizes interfilament coupling loss as an effective intrawire heat deposition mechanism, which, in principle, is faster than thermal diffusion. Furthermore, the CLIQ technology is based on simple and robust electrical components in contact with the coil only in a limited number of easily accessible and well-insulated points. Hence, expected occurrence of failure and electrical breakdown is significantly reduced. As a case study, the design of a CLIQ-based protection system for a 14-m-long 16-T Nb 3Sn block-coil dipole magnet is demonstrated here. Various magnet design features can be adjusted to improve CLIQ performance and optimize its integration in the magnet system. CLIQ provides future magnet designers with a solution for a very effective, yet electrically robust, quench protection system, resulting in better magnet performance and lower cost than would be possible with a traditional approach to magnet protection.