Numerical modelling for divertor design of the WEST device with a focus on plasma–wall interactions

TLDR

Steady‑state operation of WEST requires understanding thermal loads on all plasma‑facing components and the dominant tungsten contamination from the main chamber. The study aims to enhance the plasma–wall interface model by incorporating sheath physics derived from 1D particle‑in‑cell simulations. The authors implemented and compared multiple prompt redeposition models, using the new SolEdge2D–EIRENE code to simulate plasma up to the first wall. The modelling demonstrates that redeposition significantly influences the balance between divertor and main‑chamber tungsten sources, validating the new code’s capability to capture edge plasma–wall interactions.

Abstract

In the perspective of operating tungsten monoblocks in WEST, the ongoing major upgrade of the Tore Supra tokamak, a dedicated modelling effort has been carried out to simulate the interaction between the edge plasma and the tungsten wall. A new transport code, SolEdge2D–EIRENE, has been developed with the ability to simulate the plasma up to the first wall. This is especially important for steady state operation, where thermal loads on all the plasma facing components, even remote from the plasma, are of interest. Moreover, main chamber tungsten sources are thought to dominate the contamination of the plasma core. We present here in particular new developments aimed at improving the description of the interface between the plasma and the wall, namely a way to treat sheath physics in a more faithful way using the output of 1D particle in cell simulations. Moreover, different models for prompt redeposition have been implemented and are compared. The latter is shown to play an important role in the balance between divertor and main chamber sources.