Complete suppression of flux instabilities in ramped superconducting magnets with synchronous temperature-modulated Jc

Abstract

Nonlinear multi-field coupling as an intrinsic property of complex physical systems often leads to abrupt and undesired instabilities. For current-ramped high-field Nb3Sn magnets, frequent flux jumps are observed, which easily causes premature quenches and requires prolonged and resource-intensive magnet training process. In this study, we propose a paradigm-shifting methodology framework that achieves complete suppression of thermomagnetic instabilities through synchronized temperature-modulated critical current density (Jc). Through numerical simulations of flux jumps in multifilamentary Nb3Sn wires at various temperatures, we construct thermomagnetic stability diagram in the Ha-T plane. The simulated results are in good agreement with experiments, confirming that the synchronized temperature ramp-down can fully eliminate flux jumps. We reveal the underlying mechanism of enhancing the thermomagnetic stability arises from that synchronized temperature ramp-down can continuously tune both Jc and its slope. Furthermore, we explore the thermomagnetic instabilities of current-ramped superconducting magnets through large-scale GPU-optimized algorithm. The flux jump and quench diagram in the Ia-T plane are obtained. It indicates that the temperature ramp-down can completely suppress flux jumps without compromising Jc at high magnetic fields. Importantly, this method does not require modifications to the superconducting microstructures or fabrication process, offering a practical and broadly applicable solution. The findings not only provide a robust method for stabilizing various superconducting magnet systems, including high-temperature superconducting magnets wound with second-generated (2G) coated tapes, but also suggest a generalizable strategy for controlling instability in other nonlinear non-equilibrium physical systems.