18th Technical Meeting on Energetic Particles in Magnetic Confinement Systems

Global calculation of shear Alfvén waves inside magnetic islands.

Not scheduled

20m

Oral Multiscale Physics and Instabilities involving Energetic Particles in Burning Plasmas

Speaker

Matthew Thomas (Australian National University)

Description

Recent work [1] has investigated the effect of a magnetic island chain modification on the shear Alfvén continuum for a large aspect tokamak using ideal MHD theory. By creating new flux based magnetic island coordinates, it was shown that the magnetic island chain reduces the width of the TAE gap in the shear Alfvén continuum.

This raises the possibility that a TAE, originally experiencing minimal damping, may experience significant continuum damping due to the island.
A major problem is the straight field line flux coordinates used in previous calculations. Due to the coordinate singularity at the sepratrix, these coordinates are not appropriate for studying a global mode.

We show that typical toroidal magnetic coordinates can be used to resolve the magnetic island SAW structure. These results are then compared to the SAW spectrum predicted using magnetic island coordinates [2].

[1] Z. S. Qu, M. J. Hole, Plasma Physics and Controlled Fusion 2023, 65, 025002
[2] A. Könies et al., Nuclear Fusion 2024, 64, 054001.