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

Abstract

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.