Speaker
Description
High-temperature superconducting (HTS) coated conductor (CC) magnets have the potential to reach high fields for accelerators, fusion devices, and user magnets, but protecting them against quench-induced damage remains a central obstacle to their deployment. Compared with low-temperature superconductors (LTS), HTS combine slow normal-zone propagation and high minimum quench energy. Passive and active normal zone propagation that serve LTS magnets well are largely ineffective for HTS. Whereas for LTS limiting quench voltage and temperature during quench are important, for HTS CC also superconductor-level stresses due to the risk of delamination and, for no-insulation (NI) coils, the redistribution of current, energy, and force density bring additional challenges.
This talk provides an overview of strategies for protecting HTS magnets. The stored magnetic energy can be distributed (propagated) within the magnet or removed (extracted) from it by active or passive means through the conductor, coupled coils, structures, or power source. NI coils receive attention: current redistribution lowers the current density in the quenched region but has the potential to dramatically increase thermo-mechanical stress in other places of the magnet, and this is often hard to predict and design against. Energy extraction, quench heaters, coupling-loss-induced quench (CLIQ), the recent Energy Shift with Coupling (ESC), and the intrinsic current sharing of NI and metal-insulation windings are compared.
A recurring theme for HTS protection is that the quench analysis demands coupled magneto-thermal-mechanical modelling and constrains conductor and magnet design from the outset. The talk highlights where numerical modelling is decisive and current STEAM framework software capabilities, as well as the need for HTS-specific additional capabilities. Various tools will be presented with their differences highlighted. The impact and relevance of quench detection and protection for the cooling and cryogenics of HTS magnets will also be discussed.
| Submitters Country | Switzerland |
|---|---|
| Are you a student? | No |
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