On the existence of canonical gyrokinetic variables for chaotic magnetic fields

TL;DR

This paper investigates the conditions under which canonical gyrokinetic variables, including the gyrophase-angle and its conjugate momentum, can exist in chaotic magnetic fields, addressing a fundamental challenge in plasma physics.

Contribution

It provides a theoretical analysis of the existence conditions for gyrokinetic canonical variables in complex magnetic field configurations.

Findings

Identifies conditions necessary for the existence of gyrokinetic canonical variables.

Highlights limitations in defining these variables in chaotic magnetic fields.

Contributes to the theoretical foundation of gyrokinetic plasma modeling.

Abstract

The gyrokinetic description of particle dynamics faces a basic difficulty when a special type of canonical variables is sought, i.e., the so-called \textit{gyrokinetic canonical variables}. These are defined in such a way that two of them are respectively identified with the gyrophase-angle, describing the fast particle gyration motion around magnetic field lines, and its canonically conjugate momentum. In this paper we intend to discuss the conditions of existence for these variables.