  This study traces the emergence of sheared axial flow from collisional drift
wave turbulence with broken symmetry in a linear plasma device---CSDX. As the
density profile steepens, the axial Reynolds stress develops and drives a
radially sheared axial flow that is parallel to the magnetic field. Results
show that the non-diffusive piece of the Reynolds stress is driven by the
density gradient and results from the spectral asymmetry of the turbulence and
thus is dynamical in origin. Taken together, these findings constitute the
first simultaneous demonstration of the causal link between the density
gradient, turbulence and stress with broken spectral symmetry, and the mean
axial flow.
