Method of Quench Detection in HTS Magnets

Commonwealth Fusion Systems (CFS) is the world leader in developing High Temperature Superconducting (HTS) magnet technology for high-field compact tokamaks, SPARC and next generation ARC. As part of these and associated energy generation related projects CFS achieved significant progress in developing, building, and testing several high-field magnets both using no-insulation winding technique and traditional winding using an insulated cable. One major takeaway is that to be quench-resilient high-field, high stored energy HTS magnets need quench detection (QD) and quench protection (QP) features. The general situation with HTS magnets indicates that traditional voltage-based QD methods are at least difficult, as for insulated magnets, or just impossible, as for the no-insulation magnets. Alternative methods of QD are considered. We are proposing an apparently universal conceptual approach to QD. It is based on voltage measurements, reliable, relatively simple, provides an exceptionally good noise rejection and can be used with all the above insulated and no-insulation magnets, as well as many other magnet designs, not only HTS but also Low Temperature Superconducting. QP is suggested but ls left mostly outside the scope of this study.