Description
The EAST superconducting tokamak, with Mo first walls and ITER-like W divertors, has developed and tested a Shattered Pellet Injection (SPI) system [1,2] and two Massive Gas Injection (MGI) systems [3] for disruption mitigation. Neon SPI experiments revealed key disruption dynamics including helical impurity transport and radiation evolution. Compared with MGI, SPI shows superior performance: a shorter TQ, longer CQ, stronger core radiation, and ~40% lower electron temperature with ~50% reduced divertor heat flux [4]. It also generates a more uniform poloidal radiation profile near the plasma core and avoids cold VDEs seen in MGI disruptions. Impurity injection, by either SPI or MGI, can trigger MHD mode switching from an inherent n=1/2 to a new n=1 with reversed rotation, attributed to impurity–plasma interactions [5]. SPI parameter scans showed smaller fragments ablate rapidly at the edge, while larger ones penetrate deeper and ablate slowly. Although ISPI generated more uniform TQ radiation, its poorer assimilation caused a longer pre-TQ phase and weaker halo current mitigation [6]. Finally, RE plateau formation was achieved with Ar-MGI, critically dependent on pre-disruption non-Maxwellian seed electrons and suppressed by MHD activity during TQ. These EAST results provide key data and insights for ITER disruption mitigation system design and operation.
Reference
[1] Yuan J.S. et al 2023 Fusion Eng. Des. 191 113567
[2] Yuan J.S. et al 2024 Fusion Eng. Des. 205 114551
[3] Zhuang H.D. et al 2015 Rev. Sci. Instrum. 86 053502
[4] Yuan J.S. et al 2023 Nucl. Fusion 63 106008
[5] Zhao S.B. et al 2024 Nucl. Fusion 65 016048
[6] Li L. et al 2025 Nucl. Fusion 65 086012