Avoiding Tokamak disruptions by applying static magnetic fields that align locked modes with stabilizing wave-driven currents

TL;DR

This paper demonstrates a novel method to prevent tokamak disruptions by using static magnetic fields and millimetre waves to control and stabilize locked magnetic islands, thereby maintaining plasma confinement.

Contribution

The study introduces a new technique combining 3D magnetic fields and wave-driven currents to suppress locked islands and avoid major disruptions in tokamak plasmas.

Findings

Locked islands were successfully suppressed for the first time.

Disruption was avoided, restoring high confinement and pressure.

Stabilization depended on wave power and phase alignment.

Abstract

Non-rotating (`locked') magnetic islands often lead to complete losses of confinement in tokamak plasmas, called major disruptions. Here locked islands were suppressed for the first time, by a combination of applied three-dimensional magnetic fields and injected millimetre waves. The applied fields were used to control the phase of locking and so align the island O-point with the region where the injected waves generated non-inductive currents. This resulted in stabilization of the locked island, disruption avoidance, recovery of high confinement and high pressure, in accordance with the expected dependencies upon wave power and relative phase between O-point and driven current.