X-point-position-dependent intrinsic rotation in the edge of TCV

A simple transport-based theoretical model predicts that intrinsic toroidal rotation in the tokamak edge should depend strongly on $R_X$, the major-radial position of the X-point, including a sign change to counter-current rotation for adequately outboard X-point. To test the prediction, an $R_X$ scan was conducted in Ohmic L-mode shots on TCV, in both USN and LSN configurations. The strong linear dependence on $R_X$ was experimentally observed, with quantitative magnitude corresponding to a realistic value for the theory's corresponding input parameter. Although peaked rotation profiles complicate the comparison of absolute rotation values, the data is consistent with the predicted sign change. The core rotation profile shifted fairly rigidly with the edge rotation value, maintaining a relatively constant core rotation gradient. Core rotation reversals, triggered accidentally in a few shots, had little effect on the edge rotation velocity. Edge rotation was modestly more counter-current in USN than LSN discharges.