Radial profiles of the parallel-radial Reynolds stress component, proportional to the cross correlation between parallel and radial fluctuating velocities, have been measured in the plasma boundary region of the TJ-II stellarator. Experimental results show the existence of significant parallel turbulent forces at plasma densities above the threshold value to trigger perpendicular E x B sheared flows. This finding provides the first experimental evidence of the role of parallel turbulence forces on edge momentum redistribution in fusion devices.
