Application of Lagrangian techniques for calculating the on-axis rotational transform
Plasma Physics
2025-02-19 v1
Abstract
The Floquet exponents of periodic field lines are studied through the variations of the magnetic action on the magnetic axis, which is assumed to be elliptical. The near-axis formalism developed by Mercier, Solov'ev and Shafranov is combined with a Lagrangian approach. The on-axis Floquet exponent is shown to coincide with the on-axis rotational transform, and this is a coordinate-independent result. A discrete solution suitable for numerical implementation is introduced, which gives the Floquet exponents as solutions to an eigenvalue problem. This discrete formalism expresses the exponents as the eigenvalues of a matrix.
Keywords
Cite
@article{arxiv.2404.17531,
title = {Application of Lagrangian techniques for calculating the on-axis rotational transform},
author = {S. Guinchard and W. Sengupta and S. R. Hudson},
journal= {arXiv preprint arXiv:2404.17531},
year = {2025}
}