Constructing precisely quasi-isodynamic magnetic fields

TL;DR

This paper introduces a new numerical method for designing quasi-isodynamic stellarator magnetic fields that exhibit excellent particle confinement and minimal neoclassical transport, especially effective in single-period configurations.

Contribution

A novel numerical approach for constructing quasi-isodynamic magnetic fields with improved confinement properties and analysis of their physical characteristics and stability.

Findings

Effective in single-field period configurations

Enhanced particle confinement and reduced transport

Insights into magnetic axis properties and stability

Abstract

We present a novel method for numerically finding quasi-isodynamic stellarator magnetic fields with excellent fast-particle confinement and extremely small neoclassical transport. The method works particularly well in configurations with only one field period. We examine the properties of these newfound quasi-isodynamic configurations, including their bootstrap currents, particle confinement, and available energy for trapped-electron driven turbulence, as well as the degree to which they change when a finite pressure profile is added. We finally discuss the differences between the magnetic axes of the optimized solutions and their respective initial conditions, and conclude with the prospects for future quasi-isodynamic optimization.