Localization of MHD and fast particle modes using reflectometry in ASDEX Upgrade.

The radial structure of toroidal Alfvén eigenmodes (TAEs) is of great importance for comparison with theoretical predictions. A dual-channel fast frequency hopping millimeter-wave reflectometer installed on the ASDEX Upgrade tokamak is capable of measuring density fluctuations from the plasma edge to core, allowing the radial eigenfunction of n = 4 TAE and edge MHD modes to be obtained using phase perturbation and coherence data analysis techniques. The two techniques reveal similar results, and in particular the radial structure of the n = 4 TAE is found to be in good agreement with numerical predictions from linear gyrokinetic simulations. The first results of the radial localization of Alfvén cascades are also presented. [ABSTRACT FROM AUTHOR]