The project proposes to perform the first global simulations of plasma fluid turbulence in the W7-AS stellarator.
The simulations will be performed with GBS, a three-dimensional turbulence code that solves the drift- reduced Braginskii equations in a toroidal domain and with first-principles sheath boundary conditions at the plasma-wall transition. GBS resolves the complex interplay between plasma sources, turbulent transport, equilibrium drifts, as well as parallel losses in the scrape-off-layer (SOL). Recently, GBS simulations were validated against experiments in the TJ-K, a small size stellarator.
The goal of this project is to scale up in size and relevance, and simulate the plasma dynamics in W7-AS, the first optimized stellarator in the Wendelstein line and the predecessor of the W7-X, the largest stellarator in the world. W7-AS was also equipped with a large set of edge diagnostics that allowed detailed measurement of fluctuations in the boundary of the device.
The results of the proposed GBS simulations will allow investigating and characterizing the role of turbulent transport in the island region of W7-AS, predict the level and nature of the fluctuations, as well as the SOL equilibrium profiles forming in different configurations, thereby promoting a validation of the model against experimental measurements.
Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.