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  • Letter
  • Open Access

Prevention of core particle depletion in stellarators by turbulence

H. Thienpondt*, J. M. García-Regaña, I. Calvo, J. A. Alonso, J. L. Velasco, and A. González-Jerez

M. Barnes

K. Brunner, O. Ford, G. Fuchert, J. Knauer, E. Pasch, and L. Vanó

The Wendelstein 7-X Team

  • Laboratorio Nacional de Fusión, CIEMAT, 28040 Madrid, Spain

  • Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, United Kingdom

  • Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany

  • *Hanne.Thienpondt@ciemat.es
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Phys. Rev. Research 5, L022053 – Published 13 June, 2023

DOI: https://doi.org/10.1103/PhysRevResearch.5.L022053

Abstract

In reactor-relevant plasmas, neoclassical transport drives an outward particle flux in the core of large stellarators and predicts strongly hollow density profiles. However, this theoretical prediction is contradicted by experiments. In particular, in Wendelstein 7-X, the first large optimized stellarator, flat or weakly peaked density profiles are generally measured, indicating that neoclassical theory is not sufficient and that an inward contribution to the particle flux is missing in the core. In this Research Letter, it is shown that the turbulent contribution to the particle flux can explain the difference between experimental measurements and neoclassical predictions. The results of this Research Letter also prove that theoretical and numerical tools are approaching the level of maturity needed for the prediction of equilibrium density profiles in stellarator plasmas, which is a fundamental requirement for the design of operation scenarios of present devices and future reactors.

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Phys. Rev. Research 5, L022053– Published 13 June, 2023
  • Received 16 October 2022
  • Accepted 10 May 2023
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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.

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