A neoclassically optimized compact stellarator with four planar coils

TL;DR

This paper presents a neoclassically optimized, compact stellarator design with only four simple planar coils, achieving excellent confinement by minimizing effective ripple and significantly reducing particle diffusion compared to CNT.

Contribution

It introduces a novel stellarator configuration with a minimal coil set and optimized coil shapes for improved neoclassical confinement.

Findings

Effective ripple is minimized in the plasma core.

Particle diffusion coefficient is ten times lower than CNT.

Design uses only four planar coils, including interlocking elliptical and circular coils.

Abstract

A neoclassically optimized compact stellarator with simple coils has been designed. The magnetic field of the new stellarator is generated by only four planar coils including two interlocking coils of elliptical shape and two circular poloidal field coils. The interlocking coil topology is the same as that of the Columbia Non-neutral Torus (CNT). The new configuration was obtained by minimizing the effective helical ripple directly via the shape of the two interlocking coils. The optimized compact stellarator has very low effective ripple in the plasma core implying excellent neoclassical confinement. This is confirmed by the results of the drift-kinetic code SFINCS showing that the particle diffusion coefficient of the new configuration is one order of magnitude lower than CNT's.