Survey of the Edge Radial Electric Field in L-mode Tcv Plasmas Using Doppler Backscattering

A Doppler backscattering (DBS) diagnostic has recently been installed on the Tokamak & agrave; Configuration Variable (TCV) to facilitate the study of edge turbulence and flow shear in a versatile experimental environment. The dual channel V-band DBS system is coupled to TCV's quasi-optical diagnostic launcher, providing access to the upper low-field side region of the plasma cross-section. Verifications of the DBS measurements are presented. The DBS equilibrium v perpendicular to profiles are found to compare favorably with gas puff imaging (GPI) measurements and to the Er inferred from the radial force balance of the carbon impurity. The radial structure of the edge ErxB equilibrium flow and its dependencies are investigated across a representative set of L-mode TCV discharges, by varying density, auxiliary heating and magnetic configuration.