Back to the Figure-8 Stellarator

TL;DR

This paper revisits the historic figure-8 stellarator design, proposing a modern, optimized version that offers high stability, simple construction, and planar coils, enabled by recent theoretical and numerical advances in stellarator physics.

Contribution

It introduces a novel, optimized figure-8 stellarator design with planar coils, leveraging recent theoretical and numerical progress in quasi-isodynamic stellarator research.

Findings

Potential for high plasma stability.

Design admits planar coils, simplifying construction.

First quasi-isodynamic stellarator with planar coil capability.

Abstract

The first stellarator design was a simple tube of plasma twisted and closed on itself in the form of a figure-8. The line of such devices, however, was quickly ended over concerns related to plasma stability. We revisit the figure-8 concept, re-imagined as a modern optimized stellarator, and find the potential for a high degree of stability, as well as exceptionally simple construction. In particular, the design that we find admits planar coils, and is the first quasi-isodynamic stellarator design to have this property. Our work is made possible by recent theoretical progress in the near-axis theory of quasi-isodynamic stellarators, combined with fundamental progress in the numerical solution of three-dimensional magnetohydrodynamic equilibria that cannot be well represented using traditional cylindrical coordinates.