Experimental Observation of the Toroidal Flow Shear in the Edge of the SUNIST

Abstract

In the edge plasma of the SUNIST spherical tokamak, the toroidal flow velocity v_φ, the poloidal shear layer and the fluctuation-driven particle transport fluxes Γ_r have been simultaneously measured with Mach probe and Langmuir probe arrays, respectively. The results indicate that the v_φ has a radial gradient dv_φ/dr. The change of the dv_φ/dr positively correlates with both the poloidal shear and the suppression of the Γ_r. Such coincidence suggests that the toroidal sheared flow may play an important role in the suppression of the edge fluctuation-driven transport in STs.