Experimental observation of the toroidal flow shear in the edge of the SUNIST

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