Symmetries of the Electromagnetic Turbulence in a Tokamak Edge

TL;DR

This paper develops a simplified model for electromagnetic turbulence in a Tokamak edge, revealing a dominant Fourier mode and the stability of two-dimensional turbulence despite magnetic fluctuations.

Contribution

It introduces a reduced single-equation model capturing key turbulence features, including symmetry properties and the behavior of non-axisymmetric modes.

Findings

Existence of a specific Fourier branch in turbulence dynamics

Two distinct physical regimes identified for non-axisymmetric fluctuations

Reduced model effectively describes turbulence with magnetic fluctuations

Abstract

We construct the low-frequency formulation of the turbulence characterizing the plasma in a Tokamak edge. Under rather natural assumptions we demonstrate that, even in the presence of poloidal magnetic fluctuations, it is possible to deal with a reduced model for the turbulence dynamics. This model relies on a single equation for the electric potential, from which all the physical turbulent properties can be calculated. The main result of the present analysis concerns the existence of a specific Fourier branch for the dynamics which demonstrate the attractive character of the two-dimensional turbulence with respect to non-axisymmetric fluctuations. The peculiar nature of this instability, affecting the non-axially symmetric modes, is discussed in some detail, by recovering two different physical regimes.