High frequency geodesic acoustic modes in electron scale turbulence
Journal article, 2013

In this work the finite β-effects of an electron branch of the geodesic acoustic mode (el-GAM) driven by electron temperature gradient (ETG) modes is presented. The work is based on a fluid description of the ETG mode retaining non-adiabatic ions and the dispersion relation for el-GAMs driven non-linearly by ETG modes is derived. The ETG growth rate from the fluid model is compared with the results found from gyrokinetic simulations with good agreement. A new saturation mechanism for ETG turbulence through the interaction with el-GAMs is found, resulting in a significantly enhanced ETG turbulence saturation level compared with the mixing length estimate. It is shown that the el-GAM may be stabilized by an increase in finite β as well as by increasing non-adiabaticity. The decreased GAM growth rates is due to the inclusion of the Maxwell stress.


Transport Barriers


Zonal Flows


Johan Anderson

Chalmers, Applied Physics, Nuclear Engineering

Andreas Skyman

Chalmers, Earth and Space Sciences, Plasma Physics and Fusion Energy

Hans Nordman

Chalmers, Earth and Space Sciences, Plasma Physics and Fusion Energy

Raghvendra Singh

Institute for Plasma Research India


P.K. Kaw

Institute for Plasma Research India

Nuclear Fusion

0029-5515 (ISSN)

Vol. 53 12 article nr. 123016- 123016

Subject Categories

Physical Sciences

Fusion, Plasma and Space Physics

Areas of Advance



Basic sciences


C3SE (Chalmers Centre for Computational Science and Engineering)



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