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High frequency geodesic acoustic modes in electron scale turbulence

Johan Anderson (Institutionen för teknisk fysik, Nukleär teknik) ; Andreas Skyman (Institutionen för rymd- och geovetenskap, Plasmafysik och fusionsenergi) ; Hans Nordman (Institutionen för rymd- och geovetenskap, Plasmafysik och fusionsenergi) ; Raghvendra Singh ; Predhiman Kaw
Nuclear Fusion (0029-5515). Vol. 53 (2013), 12, p. article nr. 123016.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: ETG, GAM, Zonal Flows, Transport Barriers



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Denna post skapades 2013-11-19. Senast ändrad 2016-10-18.
CPL Pubid: 187038

 

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