Extending near-axis equilibria in DESC

TL;DR

This paper introduces a new method to construct global stellarator equilibria from near-axis descriptions using the DESC code, ensuring correct asymptotic behavior and facilitating future optimization of magnetic confinement devices.

Contribution

A novel approach to generate global equilibria from near-axis models with guaranteed asymptotic properties using the DESC code.

Findings

Successfully constructed global equilibria with near-axis asymptotics

Benchmarking confirms the method's accuracy and consistency

Enables efficient coupling of near-axis and global equilibrium frameworks

Abstract

The near-axis description of optimised stellarator fields has proven to be a powerful tool both for design and understanding of this magnetic confinement concept. The description consists of an asymptotic model of the equilibrium in the distance from its centermost axis, and is thus only approximate. Any practical application therefore requires the eventual construction of a global equilibrium. This paper presents a novel way of constructing global equilibria using the \texttt{DESC} code that guarantees the correct asymptotic behaviour imposed by a given near-axis construction. The theoretical underpinnings of this construction are carefully presented, and benchmarking examples provided. This opens the door to an efficient coupling of the near-axis framework and that of global equilibria for future optimisation efforts.