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 ( and ) 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.
Sheared flows and transition to improved confinement regime in the TJ-II stellarator