Excitation of geodesic acoustic mode (GAM) by collisionless trapped electron mode (CTEM) is studied within the framework of nonlinear gyrokinetic theory. The dispersion relation describing GAM excitation by drift wave turbulence valid for arbitrary k⊥ρi is derived. Here, k⊥ and ρi are, respectively, perpendicular wave vector and thermal ion Larmor radius. It is found that the parametric decay process of CTEM into a GAM and a CTEM sideband is unstable in both small and large k⊥ρi regimes due to, respectively, ion and trapped electron nonlinearity. For moderate k⊥ρi, however, there exists a negligible-GAM-excitation state where ion and trapped electron nonlinearities cancel each other. © 2014 IAEA, Vienna.

Nonlinear excitation of geodesic acoustic mode by collisionless trapped electron mode

Zonca, F.
2014

Abstract

Excitation of geodesic acoustic mode (GAM) by collisionless trapped electron mode (CTEM) is studied within the framework of nonlinear gyrokinetic theory. The dispersion relation describing GAM excitation by drift wave turbulence valid for arbitrary k⊥ρi is derived. Here, k⊥ and ρi are, respectively, perpendicular wave vector and thermal ion Larmor radius. It is found that the parametric decay process of CTEM into a GAM and a CTEM sideband is unstable in both small and large k⊥ρi regimes due to, respectively, ion and trapped electron nonlinearity. For moderate k⊥ρi, however, there exists a negligible-GAM-excitation state where ion and trapped electron nonlinearities cancel each other. © 2014 IAEA, Vienna.
collisionless trapped electron mode;zonal structure;gyrokinetic theory;geodesic acoustic mode
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12079/2870
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