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  • Letter
  • Open Access
  • Access by Xinjiang University

Optimizing particle transport for enhanced confinement in quasi-isodynamic stellarators

A. Bañón Navarro*,†, A. Di Siena*,‡, and F. Jenko

A. Merlo and E. Laude

  • Proxima Fusion, Flößergasse 2, 81369 Munich, Germany

  • *These authors contributed equally to this work.
  • †Contact author: alejandro.banon.navarro@ipp.mpg.de
  • ‡Contact author: alessandro.di.siena@ipp.mpg.de
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Phys. Rev. E 113, L043204 – Published 21 April, 2026

DOI: https://doi.org/10.1103/fbbl-ps5l

Abstract

Despite substantial advances in mitigating turbulent heat losses, including those achieved in the stable quasi-isodynamic design family [J. Plasma Phys. 89, 905890504 (2023); PRX Energy 3, 023010 (2024)], particle confinement remains a principal performance bottleneck in modern quasi-isodynamic stellarators, a challenge not fully addressed in previous optimization efforts. Using gyrokinetic simulations within the gene-Tango framework, we identify suppressed inward thermodiffusion, caused by unfavorable magnetic geometry, as the primary cause. To overcome this limitation, we design a new configuration with a reduced mirror ratio, which enhances the contribution of passing electrons to the inward particle flux. This facilitates the formation of strongly peaked density profiles, suppresses turbulence, and leads to a substantial improvement in confinement. Our optimized configuration achieves nearly a twofold increase in energy confinement compared to Stellaris, highlighting the crucial role of optimizing particle transport in next-generation stellarator designs.

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Phys. Rev. E 113, L043204– Published 21 April, 2026
  • Received 30 July 2025
  • Accepted 13 November 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

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