Erlangen 2026 – scientific programme

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P: Fachverband Plasmaphysik

P 7: Magnetic Confinement III

P 7.3: Talk

Tuesday, March 17, 2026, 17:10–17:35, KH 02.016

Reduced Models for Turbulent Transport in W7-X — •Don Lawrence Carl Agapito Fernando¹, Ionut-Gabriel Farcaş², Gabriele Merlo¹, Alejandro Bañón Navarro¹, and Frank Jenko¹ — ¹Max-Planck-Institut für Plasmaphysik, Garching, Germany — ²Virginia Tech, Blacksburg, Virginia, USA

High-fidelity, first-principles simulations have become indispensable for understanding the complex turbulence dynamics in fusion plasmas. However, their high computational cost limits their use for rapid profile prediction, parameter scans, and optimization studies. This motivates the development of reduced models with robust predictive accuracy.

Here, we present reduced models for turbulent heat and particle fluxes in W7-X. These models are constructed from a database of adiabatic-ion electron-scale and kinetic-electron ion-scale simulations generated with the GENE-KNOSOS-Tango framework, supplemented by a number of simulations driven by a structure-exploiting sparse grid approach. An active-learning algorithm was used to identify the most informative data points for model construction and regression.

The resulting models depend on key plasma parameters such as normalized temperature gradients, the ratio of temperature to density gradients, and the E × B shear. Model predictions show good agreement with reference gyrokinetic fluxes within the training domain and at additional test positions. We also investigate strategies to generalize the models across arbitrary radial positions. These turbulent transport models for W7-X paves the way for faster profile prediction and reduces the computational effort of simulation-heavy workflows.

Keywords: Turbulence; Gyrokinetics; Reduced Models