Speaker
Mr
Johan Anderson
(USA)
Description
There has been overwhelming evidence that coherent structures such as vortices, streamers and zonal flows (m = n = 0, where m and n are the poloidal and toroidal modenumbers respectively) play a critical role in determining the overall transport in magnetically confined plasmas [1]. Some of these coherent structures, so called streamers, are radially elongated structures that cause intermittent, bursty events, which can mediate significant transport of heat and particles, for instance, imposing a large heat load on container walls.
In this work the presence of a high frequency branch of the geodesic acoustic mode (GAM)driven by electron temperature gradient (ETG) modes is demonstrated. The work is based on a fluid description of the ETG mode retaining non-adiabatic ions and the dispersion relation for high frequency GAMs driven nonlinearly by ETG modes is derived. A new saturation mechanism for ETG turbulence through the interaction with high frequency GAMs is found, resulting in a significantly enhanced ETG turbulence saturation level compared to the mixing length estimate.
Country or International Organization of Primary Author
Sweden
Primary author
Mr
Johan Anderson
(USA)
Co-authors
Mr
Andreas Skyman
(Chalmers University of Technology)
Prof.
Hans Nordman
(Chalmers University of Technology)
Prof.
Predhiman Kaw
(IPR)
Prof.
Raghvendra Singh
(ITER/IPR)
