On the stability of interchange mode turbulence with respect to excitation of large-scale flows

Zhanna Andrushchenko (1) , Ingmar Sandberg (2) , Vladimir Pavlenko (3)

1 Department of Biometry and Engineering
2 Department of Electrical and Computer Engineering
3 Department of Physics and Astronomy [Uppsala]

The coupled dynamics of small- and large-scale flute type perturbations in a magnetized plasma is considered. It is shown that the small-scale wave packets are unstable with respect to the low frequency and long wavelength perturbations. These perturbations are accompanied by the excitation of the long wavelength modes of the density and velocity. One can distinguish two regimes of this parametric instability similar to the case of beam-plasma instability. The instability is of the resonant type (kinetic regime), when the instability growth rate is smaller than the spectral width of the small-scale flute fluctuations. In the opposite case, the instability becomes the coherent hydrodynamic type (hydrodynamic regime), so that all harmonics grow coherently. It is suggested this generic instability is responsible for the generation of mean flows, so called zonal flows and streamers, in magnetized plasma.

Mots clés: flute mode; turbulence.; zonal flow; streamer; turbulence

Domaines: Physique des plasmas [physics.plasm-ph]

Zhanna Andrushchenko, Ingmar Sandberg, Vladimir Pavlenko. On the stability of interchange mode turbulence with respect to excitation of large-scale flows. 2004. ⟨hal-00001857⟩