A new combined method for an investigation of the MHD activities in fusion experiments has been developed. The main advantages of this approach are the simultaneous use of several diagnostics (magnetic probes, soft X-ray cameras, electron cyclotron emission and motional Stark effect diagnostics) and the possibility for a direct comparison of theory predictions with the experimental observations. This method has been implemented into the MHD Interpretation Code (MHD-IC) and allows to investigate complicated mode structures which are not resolved by the available tools (tomography etc.). The code simulates experimental observations related to a given plasma perturbation for the diagnostics mentioned above, accounting for real plasma geometry and for measured plasma parameters. Then the calculated values are compared with the corresponding experimental data. The method has been successfully applied to different types of MHD instabilities on ASDEX Upgrade. For example, the investigation of fishbone activities in the conventional scenario shows that the displacement eigenfunction is an ideal (1,1) kink mode which get a resistive character for $\beta_{N} > 1.8$. The main analysis efforts however were focused on more demanding examples due to the more complicated mode structure in advanced tokamak scenarios. As an example, in this case the displacement eigenfunction for double tearing modes (DTM) was obtained using MHD-IC code. The growth rate of the DTM calculated from the displacement eigenfunction agrees well with numerical MHD simulations and the experiment. The time evolution of a MHD instabilities which accompanies the formation of internal transport barriers was investigated as well. It shows the behavior of two coupled (2,1) modes. Furthermore, the MHD activity causing a disruption was investigated in typical reversed shear discharges on ASDEX Upgrade. The main reason for the disruptions is an external mode or an internal (3,1) tearing mode. In addition, the structure and the position of the observed MHD phenomena are applied to improve the equilibrium reconstruction. This betterment is especially important in the plasma core region where the large error bars of the MSE measurements do not allow for an accurate determination of the q-profile.     «

A new combined method for an investigation of the MHD activities in fusion experiments has been developed. The main advantages of this approach are the simultaneous use of several diagnostics (magnetic probes, soft X-ray cameras, electron cyclotron emission and motional Stark effect diagnostics) and the possibility for a direct comparison of theory predictions with the experimental observations. This method has been implemented into the MHD Interpretation Code (MHD-IC) and allows to investigate...     »