On the gyrocenter transform implemented on Lagrangian differential 1-form with the existence of magnetic perturbation

TL;DR

This paper critiques the standard gyrocenter transform's physical accuracy, showing it introduces unphysical terms in orbit equations due to its non-near-identity coordinate transformation, especially in the presence of magnetic perturbations.

Contribution

It identifies limitations of the conventional gyrocenter transform and emphasizes the need for a near-identity transform to avoid unphysical artifacts in orbit equations.

Findings

Standard gyrocenter transform is not a near-identity transform.

Unphysical terms appear in orbit equations due to this transform.

Magnetic perturbations exacerbate these issues.

Abstract

This paper pointed out that the usual gyrocenter transform, which implements single-parameter Lie transform perturbation theory on Lagrangian differential 1-form of the orbit of charged particles immersed in a strong magnetic field, is not a near identical coordinate transform, and further causes some unphysical terms in the eventual orbit equations.