Large-scale plasma flows destabilized by symmetric noise

Abstract

The spontaneous presence of large-scale plasma flows amid turbulence is studied by considering the stability of perturbations with small wave vector under the influence of noise. Noise represents the effect on large-scale fluctuations of micro-scale turbulence whose dynamics depend on a particular direction ŝ like drift-wave turbulence. It is shown that, if the noise spectra are symmetric and the anisotropic parts are nonzero, a new kind of kinetic response arises to destabilize perturbations mostly propagating along ŝ. If the renormalized dissipation does not overcome such destabilization, the perturbation of smallest wave vector is shown to be most unstable. Because of the incompressibility, the flow perpendicular to ŝ is, thus, the easiest to excite.

Keywords:

• electro- and magneto-hydro-dynamic turbulence

Acknowledgement

This work was supported by the National Research Foundation of Korea grant funded by the Korean Government (KRF-2008-313-C00210).