Fig. 5: Avoidance of ETB formation by optimizing error field correction.
From: Tailoring tokamak error fields to control plasma instabilities and transport
a, d (Top) Time evolution coherence measured with electron cyclotron emission imaging (ECEI), NBI power (PNBI), root sum squared coil current (I3D), and (bottom) perpendicular mode rotation (v⊥) measured with ECEI at the maximum coherence, and edge line averaged density (\({\bar{n}}_{{{{{{{{\rm{e}}}}}}}}}\)) with error field correction (EFC) to access H-mode (a #26026) and to avoid H-mode (d #26027). In order to obtain v⊥, the cross-phase was calculated using two channels in the vertical direction, and the speed was calculated using the slope of the coherent phase. The x-axis error bars in v⊥ represent the time window of data for cross-phase calculation, and the y-axis error bar in v⊥ represents 95% confidence limits for linear fitting. b, e Conditionally ensemble-averaged auto-bicoherence of the density fluctuations before the additional heating power with EFC to access H-mode (b #26026), and to avoid H-mode (e #26027). c, f Comparison of the Chirikov parameters of the island established with (c, total Chirikov) and without (f, vacuum Chirikov) 3D plasma response with EFC to access H-mode (red), to avoid H-mode (black), and proxy error field IT = 5 kA without error field correction (violet, dashed).
