A low-frequency turbulence feature appears in high-density ohmicallyheated plasma discharges in the DIII-D tokamak in which the iontemperature gradient (ITG) mode is predicted to be unstable. The featureis observed only when the density is greater than the linear ohmicconfinement saturation density. Gyrokinetic stability calculationsindicate that the ITG mode frequency is comparable to the measuredfrequency, the wavenumber measured is comparable to that predicted for theITG mode, and the linear growth rate is significantly greater in thehigh-density regime.
Density and magnetic fluctuations in type III-ELM pedestal evolution in JET: experimental and numerical characterization