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P: Fachverband Plasmaphysik

P 5: Poster Session- Helmholtz Graduate School for Plasma Physics

P 5.17: Poster

Montag, 29. Februar 2016, 16:30–19:00, Empore Lichthof

Non-perturbative kinetic influences due to energetic particles on toroidicity-induced Alfvén eigenmodes — •Christoph Slaby, Axel Könies, and Ralf Kleiber — Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Deutschland

The resonant interaction of shear Alfvén waves with energetic particles is investigated numerically in tokamak and stellarator geometry using a non-perturbative magnetohydrodynamic-kinetic (MHD-kinetic) hybrid approach in the large-aspect-ratio approximation. The focus lies on toroidicity-induced Alfvén eigenmodes (TAEs), which are most easily destabilized by a fast-particle population in fusion plasmas.

While the background plasma is treated within the framework of ideal-MHD theory, the drive of the fast particles, as well as Landau damping of the background plasma, is modelled using the drift-kinetic Vlasov equation. A fast numerical tool, STAE-K, suitable for parameter scans has been developed to solve the resulting eigenvalue problem using a Riccati shooting method.

Energetic particle modes (EPMs) are found when the pressure of the energetic particles becomes comparable to the pressure of the background plasma. It is shown that the presence of energetic particles substantially deforms the continuum such that the mode frequency can leave the toroidicity-induced continuum gap. Furthermore, effects of a finite parallel electric field and of finite gyro-radii of the bulk-plasma ions leading to the so-called radiative damping have been included. As these terms introduce higher-order derivatives to the model, they have the potential to substantially change the nature of the solution.