Assessment of density profile automatic evaluation from broadband reflectometry data

Automatic evaluation of electron density profiles from frequency modulated continuous wave (FM–CW) broadband microwave reflectometry on ASDEX Upgrade has been achieved in all plasma regimes combining a high performance system and advanced analysis tools. The results presented demonstrate the capability of the system to resolve the abrupt gradient changes occurring in the edge region during the L–H transition and in the presence of edge localized modes (ELMs). The temporal evolution of the density gradient could be obtained extending from the ohmic and L phases to the ELMy H phase. A new data analysis method that uses sets of consecutive sweeps to extract the group delay is also presented and its use versus single sweep analysis is discussed. It is shown that local perturbations may appear and disappear during the sweep time reinforcing the need to obtain redundant data in very short time intervals and apply rejection/averaging techniques.