Empirical scaling laws for local transport in neutral beam heated plasmas

Empirical scaling relations for the electron heat diffusivity χ e , the diffusion coefficient D and the inward drift velocity v in in L and H plasmas of ASDEX are presented. They hold for injection powers which are high compared with the Ohmic input. Expressing χ e in dimensionless form reveals that particle orbit, collisionality and finite beta effects are involved in the anomalous transport. The empirical χ e scaling is incompatible with theoretical expressions derived from present drift wave models and from a non-linear gyrokinetic Vlasov equation. To reconcile empirical and theoretical scalings, it seems to be necessary to include effects due to finite beta and profile parameters.