First-principles based plasma profile predictions for optimized stellarators

Nuclear Fushion

article

A. Bañón Navarro¹  A. Di Siena¹  J.L. Velasco²  F. Wilms¹  G. Merlo³  T. Windisch¹  L.L. LoDestro⁴  J.B. Parker⁴  F. Jenko¹ 

[1] Max Planck Institute for Plasma Physics;Laboratorio Nacional de Fusión CIEMAT;The University of Texas at Austin;Lawrence Livermore National Laboratory

关键词: plasma transport;    stellarators;    gyrokinetics;   

DOI  :  10.1088/1741-4326/acc3af

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

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 T_extrm i approx 1.5keV 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 T_extrm e/T_extrm iratios, 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.

【 授权许可】

Unknown