ANALYSIS OF THE ION ENERGY-TRANSPORT IN OHMIC DISCHARGES IN THE ASDEXTOKAMAK

An analysis of the local ion energy transport is performed for more th an one hundred well documented ohmic ASDEX discharges. These are chara cterized by three different confinement regimes: the linear ohmic conf inement (LOG), the saturated ohmic confinement (SOC) and the improved ohmic confinement (IOC). All three are covered by this study. To ident ify the most important local transport mechanism of the ion heat, the ion power balance equation is analysed. Two methods are used: straight forward calculations with experimental data only, and a comparison of measured and calculated profiles of the ion temperature and the ion he at conductivity, respectively. A discussion of the power balance shows that conductive losses dominate the ion energy transport in all ohmic discharges of ASDEX. Losses due to sawtooth activity play a role only inside the q = 1 surface, while at the edge convective fluxes and CX losses influence the ion energy transport. Both methods lead to the re sult that both the ion temperature and the ion heat conductivity are c onsistent with predictions of neoclassical theory. Enhanced heat losse s as suggested by theories, e.g. on the basis of eta(i) modes, can be excluded.