Erlangen 2018 – scientific programme
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P: Fachverband Plasmaphysik
P 11: Helmholtz Graduate School - Poster
P 11.18: Poster
Tuesday, March 6, 2018, 16:15–18:15, Redoutensaal
Power balance analysis of the geodesic acoustic modes. — •Ivan Novikau1, Alessandro Biancalani1, Alberto Bottino1, Garrard D. Conway1, Peter Manz1, Pierre Morel2, Özgür D. Gürcan2, and Emanuele Poli1 — 1Max-Planck-Institut für Plasmaphysik, 85748 Garching Germany — 2LPP, CNRS, École polytechnique, UPMC Univ. Paris 06, Univ. Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Universités, PSL Research University, F-91128 Palaiseau, France
Turbulence in tokamaks generates radially sheared zonal flows (ZFs). ZFs are zero frequency electrostatic ExB modes, damped mainly by collisional processes.The action of the magnetic field curvature on the ZFs gives rise to oscillations of radial electric field called the geodesic acoustic modes (GAMs). GAMs are mainly damped by collisionless wave-particle resonance, i.e, Landau damping. Zonal structures can regulate and suppress turbulence, thus reducing the radial transport. Collisional ZF and collisionless GAM damping rates constitute crucial linear parameters in the nonlinear interaction between the zonal structures and the turbulence.
In this work, the dynamics of linear and turbulence-driven GAMs is investigated with the GK electromagnetic particle-in-cell code ORB5. The development and extension of the power balance diagnostics for the contribution of different particle species in ORB5 are described. Moreover, different reduced models derived from the GK theory are used to study the efficiency of the zero-frequency zonal structures, ZFs, and their oscillatory part, GAMs, in the turbulence suppression.