First-principles based plasma profile predictions for optimized stellarators
Abstract
In the present Letter, first-of-its-kind computer simulations predicting plasma profiles for modern optimized stellarators -- while self-consistently retaining neoclassical transport, turbulent transport with 3D effects, and external physical sources -- are presented. These simulations exploit a newly developed coupling framework involving the global gyrokinetic turbulence code GENE-3D, the neoclassical transport code KNOSOS, and the 1D transport solver TANGO. This framework is used to analyze the recently observed degradation of energy confinement in electron-heated plasmas in the Wendelstein 7-X stellarator, where the central ion temperature was "clamped" to keV regardless of the external heating power. By performing first-principles based simulations, we provide key evidence to understand this effect, namely the inefficient thermal coupling between electrons and ions in a turbulence-dominated regime, which is exacerbated by the large ratios, and show that a more efficient ion heat source, such as direct ion heating, will increase the on-axis ion temperature. This work paves the way towards the use of high-fidelity models for the development of the next generation of stellarators, in which neoclassical and turbulent transport are optimized simultaneously.
Cite
@article{arxiv.2210.01667,
title = {First-principles based plasma profile predictions for optimized stellarators},
author = {A. Bañón Navarro and A. Di Siena and J. L. Velasco and F. Wilms and G. Merlo and T. Windisch and L. L. LoDestro and J. B. Parker and F. Jenko},
journal= {arXiv preprint arXiv:2210.01667},
year = {2023}
}