Ion temperature profiles and thermal conductivity analysis for Ohmic plasmas in ASDEX

Ion temperature profiles from a neutral particle analyser are used for a thorough analysis of the ion thermal conductivity. In Ohmic ASDEX plasmas, two distinct regimes of energy confinement are possible which differ in the ion heat transport properties. The Improved Ohmic Confinement regime is reached through a transition from anomalous to neoclassical ion heat transport. The transition could be caused by a modification of the sawtooth behaviour.