Edge localized modes suppression via edge E × B velocity shear induced by RF sheath of ion cyclotron resonance heating in EAST

The control of large edge localized modes (ELMs) is a critical issue for the successful operation of future burning plasma devices, such as the international thermonuclear experimental reactor (ITER) and China fusion engineering test reactor (CFETR). In this paper, we present a new active and effective means of ELM suppression using ion cyclotron resonant heating (ICRH) on the experimental advanced superconducting tokamak (EAST). We obtained the key role of the external E × B velocity shear near the pedestal top and the scrape-off-layer (SOL) induced by the RF sheath potential of ICRH in ELM suppression. The experimental results showed a positive correlation between the RF sheath and the E × B shear rate in SOL. BOUT++ simulations indicate that increased E × B velocity shear rates in the pedestal and SOL regions promote ELM suppression; thereby, supporting the experimental observations on EAST. These findings suggest a new simple approach to access the ELM suppressed regimes in plasma with low torque input as ITER baseline discharges.