Non-modal kinetic theory of the stability of the compressed-sheared plasma flows generated by the inhomogeneous microscale turbulence in the tokamak edge plasma

TL;DR

This paper develops a nonmodal kinetic theory to analyze the stability of compressed-sheared mesoscale plasma flows in tokamak edge plasma, revealing how microturbulence influences wave modes and potential evolution over time.

Contribution

It introduces a novel nonmodal kinetic framework for mesoscale plasma flow stability, accounting for inhomogeneous microturbulence effects in tokamak edge plasma.

Findings

Fourier modes are frame-dependent and appear as compressed-sheared modes in the lab frame.

An integral equation governing electrostatic potential responses is derived.

The theory shows potential transforming into zero-frequency perturbations over time.

Abstract

A nonmodal kinetic theory of the stability of the two-dimensional compressed-sheared mesoscale plasma flows, generated by the radially inhomogeneous electrostatic ion cyclotron parametric microturbulence in the pedestal plasma with a sheared poloidal flow, is developed. This theory reveals that the separate spatially uniform Fourier modes of the electrostatic responses of the ions and of the electrons on the mesoscale convective flows are determined only in the frames of references moved with velocities of the ion and electron convective flows. In the laboratory frame, these modes are observed as the compressed-sheared modes with time dependent wave numbers. The integral equation, which governs the separate Fourier mode of the electrostatic potential of the plasma species responses on the mesoscale convective flows, is derived. In this equation, the effects of the compressing and shearing of the convective flows are revealed as the time dependence of the finite ion Larmor radius effect. The solution of this equation for the kinetic drift instability displays the nonmodal transformation of the potential to the zero frequency cell-like perturbation when time elapsed.