Measurements of Reynolds stress and turbulent transport in the plasma boundary during the static dynamic ergodic divertor operation on TEXTOR

The radial profiles of electrostatic Reynolds stress and fluctuation-driven particle flux have been measured in the plasma boundary using a multi-array of fast reciprocating Langmuir probes during the static 6/2 and 3/1 mode dynamic ergodic divertor (DED) operation on TEXTOR. In the ohmic discharge phase before DED, a large radial gradient of Reynolds stress is observed around the flow shear region, suggesting the importance of turbulence-driven flows in the plasma edge. With DED, it is shown that the magnetic ergodization may suppress the Reynolds stress at the plasma boundary and thus rearrange the profile of poloidal momentum. Before DED, the local turbulent flux displays a reduction in the sheared flow layer. During the static DED phase, it is generally seen that the flux reverses direction from radially outwards to inwards in the ergodic zone. At the high DED current operation in the 3/1 configuration, a strong modification on the radial profile of the turbulent flux is observed. The results may have significant implications for the understanding of the electrostatic turbulence, fluctuation-induced flows and associated transport with magnetic stochastization.