A 10 T fast-ramping high-temperature superconducting (HTS) magnet will be designed to characterize new rare-earth permanent magnet materials. However, AC loss associated with the fast-ramping process is one of the critical issues. The primary goal of the 10 T magnet project is to find an effective way to reduce AC loss. One method is applying magnetic flux diverters (MFDs) to HTS magnets. However, the benefits of MFDs diminish in high magnetic fields that exceed the saturation field of the MFDs. To address this challenge, superconducting shielding coils (SSCs) can be an alternative solution due to their high-field diamagnetic properties.

In an initial step of this project, AC loss in a small-scale superconducting magnet was numerically studied using SSCs, MFDs, and a combination of SSCs and MFDs. The magnet consists of four double pancake coils (160 turns in total) and was wounded from 4 mm wide REBCO wire. The self-field critical current of the coil assembly is 51 A at 77 K. The simulated results show that SSCs can effectively reduce AC loss by 50% at a coil current of 50 A. This reduction can be further increased to 90% when combining SSCs and MFDs, providing an even more efficient solution.

This work was supported in “Fast-ramping superconducting magnets” funded by US Office of Naval Research under Grant award No. N629092412037.