Pedestal and E r profile evolution during an edge localized mode cycle at ASDEX Upgrade.

The upgrade of the edge charge exchange recombination spectroscopy diagnostic at ASDEX Upgrade has enabled highly spatially resolved measurements of the impurity ion dynamics during an edge-localized mode cycle (ELM) with unprecedented temporal resolution, i.e. 65 μs. The increase of transport during an ELM induces a relaxation of the ion, electron edge gradients in impurity density and flows. Detailed characterization of the recovery of the edge temperature gradients reveals a difference in the ion and electron channel: the maximum ion temperature gradient is re-established on similar timescales as , which is faster than the recovery of . After the clamping of the maximum gradient, T_i and T_e at the pedestal top continue to rise up to the next ELM while n_e stays constant which means that the temperature pedestal and the resulting pedestal pressure widen until the next ELM. The edge radial electric field E_r at the ELM crash is found to reduce to typical L-mode values and its maximum recovers to its pre-ELM conditions on a similar time scale as for n_e and T_i. Within the uncertainties, the measurements of E_r align with their neoclassical predictions for most of the ELM cycle, thus indicating that E_r is dominated by collisional processes. However, between 2 and 4 ms after the ELM crash, other contributions to flow, e.g. zonal flows or ion orbit effects, could not be excluded within the uncertainties. [ABSTRACT FROM AUTHOR]