Fourier-Hankel/Bessel space absolute equilibria of 2D gyrokinetics

TL;DR

This paper investigates the conserved invariants in 2D gyrokinetics under Fourier and Hankel/Bessel truncations, providing insights into spectral transfer processes in plasma turbulence.

Contribution

It demonstrates the ruggedness of two invariants in gyrokinetics under specific truncations and uses absolute equilibria to explain numerical turbulence results.

Findings

Identification of conserved invariants under truncations

Explanation of spectral transfer mechanisms in plasma turbulence

Clarification of recent numerical simulation results

Abstract

Two global invariants of two dimensional gyrokinetics are shown to be "rugged" (still conserved by the dynamics) concerning both Fourier and Hankel/Bessel Galerkin truncations. The truncations are made to keep only a finite range of wavenumber $\textbf{k}$ and the Hankel variable $b$ (or $z$ in the Bessel series). The absolute equilibria are used for the discussion of the spectral transfers in the configuration-velocity scale space of kinetic magnetized plasma turbulence. Some interesting aspects of recent numerical results, which were not well understood, are explained with more satisfaction.