Evolution of turbulence characteristics in the pre-precursor phase of tearing mode included disruption in the core of EAST

Abstract

Avoiding the plasma instability, especially the disruption instability, is an important problem for the stable operation of tokamak. Large-scale instabilities driven by free energy evolve nonlinearly and lead to the disruption. The microscale turbulence is highly sensitive to the change of free energy. The paper show the electron-scale turbulence evolution in the pre-precursor phase of TMs included disruption with the CO2 laser coherent scattering system in EAST. In the pre-precursor phase of disruption, it is observed that the characteristics of turbulence (e.g. intensity, spatial correlation) have obviously changed for more than 30 ms. In addition, before TM (n = 1) included major disruption, the spatial-correlation of turbulence in two regions (ρ = 0 − 0.4 and ρ = 0.4 − 0.8) increase obviously, while opposite turbulence spatial-correlation evolution was observed before TM (n = 1) included minor disruption. The warning time for disruption with microscale turbulence is competitive while 30 ms for ITER[1]. According to the experimental results in EAST, it may provide a new experimental evidence for the method improvement of predicting disruption.