Reduction of sawtooth amplitude by resonant magnetic perturbation

Abstract

Sawtooth crashes of large amplitude are detrimental to tokamak plasma confinement, and the amplitude has to be reduced for a fusion reactor.A novel method, i.e., applying m/n=2/2 resonant magnetic perturbations (RMPs), is found to be able to reduce the sawtooth magnitude in J-TEXT tokamak experiments.The penetration of RMPs and formation of 2/2 locked island are found to be related to the reduction of sawtooth magnitude.With the available 2/2 RMP field, the sawtooth mitigation is reproducibly achieved with qa < 2.8 and ne < 2×10 19 m -3 in J-TEXT.