Representing the boundary of stellarator plasmas

TL;DR

This paper introduces a simple method to uniquely represent the plasma boundary in stellarator optimization, addressing the non-uniqueness of Fourier series descriptions.

Contribution

A novel approach to eliminate arbitrariness in Fourier series representation of stellarator plasma boundaries is proposed and validated.

Findings

Method effectively removes non-uniqueness in boundary representation

Improves consistency in stellarator boundary modeling

Facilitates more reliable stellarator optimization processes

Abstract

In stellarator optimization studies, the boundary of the plasma is usually described by Fourier series that are not unique: several sets of Fourier coefficients describe approximately the same boundary shape. A simple method for eliminating this arbitrariness is proposed and shown to work well in practice.