Observation of internal transport barrier evolution in ELMy H-mode plasma on EAST tokamak

Research shows that there is an asynchronous evolution process between the internal transport barriers formed in three channels (ion temperature, electron temperature and density). Under the condition of low toroidal magnetic field (B_t ~ 1.6 T), the electron density ITB is the easiest to implement by the fueling effect of the first NBI with the least heating power. However, the n_e-ITB appear to be independent on heating power. The ion temperature ITB can be formed without reaching the threshold power under the condition of strong E×B shear flow while maintaining ITBs in ion and electron channels simultaneously requires higher heating power. Moreover, the foot of T_i-ITB formed in the strong E×B shear case is located outside that in the fishbone case, while the ITB strength remains almost unchanged. The fishbone activities do not always occur prior to ITBs formation as our previous results shown, suggesting that there may be no direct relationship between the physical process of ITBs triggering and fishbone activities.