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 capabil ity of the system to resolve the abrupt gradient changes occurring in the e dge region during the L-H transition and in the presence of edge localized modes (ELMs). The temporal evolution of the density gradient could be obtai ned extending from the ohmic and L phases to the ELMy H phase. A new data a nalysis method that uses sets of consecutive sweeps to extract the group de lay 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. (C) 2001 American Inst itute of Physics.