Local transport in tokamaks with ohmic and injection heating

The anomalous electron heat diffusivity Χe is investigated by a power scan of the injection heating and by the time evolution of L (low confinement) discharges. It is shown that deviations from the ohmic scaling occur if the non-ohmic electron heating locally exceeds the ohmic power density. The change in scaling is attributed to the injection heating with its different dependence on the plasma parameters rather than to other instabilities or saturation effects. Constraints on Χe are derived from the electron and ion energy equations and the shape of the measured electron temperature profiles. For small injection power complex Χe scalings result which cannot be represented by superposing the ohmic and L scalings. (orig.)