A new combined method for investigation of magnetohydrodynamic (MHD) activity in fusion experiments is proposed. The main advantages of this approach are the possibility of a direct comparison of theory predictions with experimental observations by the simultaneous use of several diagnostics. The method has been applied successfully to different types of instabilities in conventional and advanced tokamak scenarios in ASDEX Upgrade. As examples, double tearing mode as well as neoclassical tearing modes are considered. The combined use of different diagnostics allows an accurate determination of the mode's eigenfunction.
Chapter 3: MHD stability, operational limits and disruptions