The link between edge sheared flows and turbulence is investigated in the plasma
edge region of the TJ-II stellarator and the results are compared with results
in other devices like JET tokamak. In the TJ-II stellarator there is a threshold
density to trigger the development of edge shear flows. During sheared flow
development the degree of turbulence anisotropy is modified. The
fact that different quadratic terms in fluctuating velocities
change during edge sheared flow generation means that shear flow physics
involves 3D physics phenomena in which both perpendicular and parallel
dynamics are involved. A new strategy has been recently applied to plasma
physics to quantify the local energy transfer between flows and turbulence by
computing the production term. Experimental results show that turbulence can
act as an energy sink and energy source for the mean flow near the shear layer.
Measurements of the turbulence production show the importance of 3D effects
on the energy transfer between flows and turbulence. |