Properties of a new quasi-axisymmetric configuration

TL;DR

This paper introduces a new quasi-axisymmetric magnetic confinement configuration with low particle losses, stable MHD behavior, and promising transport properties, supported by equilibrium calculations and initial coil design analysis.

Contribution

It presents a novel, compact quasi-axisymmetric configuration with demonstrated stability, low particle losses, and comparable neoclassical transport to tokamaks, including initial coil feasibility assessment.

Findings

Fast-particle loss rates below 8% within half-radius

MHD stability limit at a normalized pressure of 3%

Neoclassical transport similar to tokamaks with a banana regime

Abstract

A novel, compact, quasi-axisymmetric configuration is presented which exhibits low fast-particle losses and is stable to ideal MHD instabilities. The design has fast-particle loss rates below 8\% for flux surfaces within the half-radius, and is shown to have an MHD-stability limit of a normalised pressure of $\langle\beta\rangle=3\%$ where $\langle\beta\rangle$ is volume averaged. The flux surfaces at various plasma betas and currents as calculated using the SPEC equilibrium code are presented. Neoclassical transport coefficients are shown to be similar to an equivalent tokamak, with a distinct banana regime at half-radius. An initial coil design study is presented to assess the feasibility of this configuration as a fusion-relevant experiment.