G. R. Tynan
University of California San Diego
Thursday, May 17, 2018
Intrinsic rotation in toroidal devices can play an important role in setting the overall beta limit due to resistive wall mode stabilization of MHD activity, and thus is of fundamental interest for magnetic fusion.Theory suggests that turbulent momentum transport can play a role in driving this rotation, but diagnostic limitations in tokamak experiments do not permit the underlying turbulence physics to be studied and thus experimental tests of theory have been limited. In this work, we present results from a cylindrical helicon plasma device that show evidence for turbulence-generated parallel flows. As the magnetic field is raised, electron pressure gradient driven collisional drift turbulence sets in and, simultaneously radially azimuthal and axial flows appear. Measurements of turbulent stress components indicate a similar onset, and the observed flows are generally consistent with the stresses and flow dissipationprofiles that are estimated from measured ion teperature profiles. A novel dynamical flow generation mechanism that does not require magnetic shear is proposed to explain the observations, and may have implications for results from tokamaks.