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The edge turbulence characteristics and the induced radial transport have been investigated in edge localized mode (ELM) suppression by using the $n = $ 4 resonant magnetic perturbation coils on EAST, with ${q_{95}} = $ 3.6 and the electron collisionality $\nu _{\text{e}}^* \approx $ 0.5. During ELM suppression, the edge turbulence is enhanced dramatically, as measured by the reciprocating probe and the poloidal correlation reflectometry. In the near SOL, the low frequency turbulence (250 kHz), which could be beneficial to form the observed turbulent transport. The estimated upstream cross-field particle flux is consistent with the total particle flux deposited on divertor targets, demonstrating that the enhanced radial turbulent particle transport is an important mechanism for particle exhaust in ELM suppression.

A newly developed radial directional electron probe (DEP) has been applied to the unidirectional electron current measurement on EAST tokamak. The DEP consists of two radial arrays of channels which have opposite directions and align along the local magnetic field line. Each radial array has 6 holes with a radial interval of 5 mm. Every channel has a hole with 0.5 mm radial width, 3 mm depth and 15° poloidal opening angle. The graphite collector embedded inside the hole is biased to positive potential to repel low energy ions, and high energy ions are blocked by the hole surface because their Larmor radii are larger than the radial width of hole. In consequence, the ion current collected by the DEP collector can be ignored in contrast with the electron current, as demonstrated by the I-V characteristics in a DEP commissioning experiment. The difference of collected current between two opposite channels signifies the unidirectional electron current in the flux tube. In a lower hybrid wave (LHW) modulation experiment, the amplitude and radial structure of unidirectional electron current induced by LHW is measured directly by this radial DEP array, and the LHW filament current covers over 20 mm radial region with a maximum of 20 A/cm2.