Edge turbulence characteristics and transport during the ELM mitigation with n=1 resonant magnetic perturbation on EAST

The edge localized mode (ELM) has been mitigated by n=1 resonant magnetic perturbation (RMP) in EAST tokamak. The turbulence characteristics and transport during the ELM mitigation have been measured by a series of diagnostics. The edge coherent mode (ECM) with a frequency about 25 kHz almost disappears when ELM is mitigated. The scrape-off layer (SOL) radial turbulent transport is measured by a four-tip Langmuir probe mounted on the manipulator at the outer midplane, exhibiting a strong enhancement of outward particle during the ELM mitigation in the SOL region (3-25 mm outside the LCFS). This enhanced outward radial transport is mainly driven by the low frequency turbulence (<50 kHz), and is compared with the particle flux deposited on divertor targets quantitatively, revealing a good agreement with each other. It is suggested that a new channel for particle exhaust induced by the low frequency turbulence is beneficial to maintain the ELM mitigation by RMP.