Speaker
Description
The US Magnet Development Program is leading the ambitious challenge of developing an accelerator dipole magnet targeting a bore field of 20 T. Among the explored designs is a 6-layer, cos-theta hybrid magnet, which includes low-temperature superconductor (LTS) and high-temperature superconductor (HTS) coils powered in series. The objective is to build a 1 m long demonstrator magnet with features that meet the operational requirements of a particle accelerator. This includes demonstrating effective magnet quench protection without relying on energy extraction, as well as scalability of the protection strategy up to a full-size, 15 m long magnet.
Protecting this high-field magnet after a quench is extremely challenging due to the high energy density, high current density, large margin to quench (particularly in the HTS coils), and highly non-uniform quench response of the HTS and LTS coils. A previous study showed that CLIQ-based protection relying on a 1 kV capacitive unit is effective in protecting such a magnet design only up to a magnetic length of about 5 m. While increasing the magnet coil size and the CLIQ charging voltage could extend this range, such approaches would have significant drawbacks, including higher costs and increased risk of electrical failure.
This study explores the application of the recently-developed Energy Shift with Coupling (ESC) technology to this magnet design. ESC relies on resistive coils integrated into the magnet cross-section, which are utilized to introduce high transient losses in the superconductor, hence quickly transitioning the superconductor to the normal state and transferring part of its stored energy to the ESC coils. Simulations performed with the STEAM-LEDET program show that a 15 m long, 20 T magnet can be effectively protected using six 1 kV ESC capacitive units powering six ESC coils, which can be integrated into the magnet without significantly altering its magnetic design. The successful application of ESC to this challenging magnet design marks a significant advancement in quench protection technology, enabling the development of next-generation high-field accelerator magnets.
