The radial structure of plasma fluctuations has been investigated in the plasma boundary region of the TJ-II stellarator. For density above the threshold for edge-sheared flow development potential fluctuations propagate predominantly radially outwards in the scrape-off-layer side of the shear layer, whereas in the edge region side the radial propagation is predominantly radially inwards with an effective velocity in the order of 1–10 km s−1. Results suggest that edge-sheared flows play a role as a source of inward and outward propagating plasma potential fluctuations.
Plasma fluctuations near the shear layer in the ATF torsatron