Simulation of Silicon Carbide as first wall material using GITR + Surface Model

Silicon Carbide(SiC) is a promising plasma-facing material for next generation fusion devices because of low hydrogenic diffusion, good mechanical and thermal properties under neutron irradiation and low Z contamination. The goal of this work is to estimate the performance of SiC as a plasma facing component by examining erosion and migration rates of silicon and carbon in the plasma and the evolution of the sub-surface concentrations. A semi-analytical surface model has been proposed that models surface material interactions (physical sputtering and reflections) with the main plasma ions and impurities. This is coupled with global particle tracking code (GITR [1]) to study erosion and transport of Si and C in the plasma. SiC samples were exposed to L-mode attached plasma using the Divertor Material Evaluation System (DiMES) on the DIII-D tokamak [2]. The coupled surface model with a homogeneous mixed material model and GITR simulations have been used to reproduce gross and net erosion rates of silicon carbide coatings in the lower divertor measured during this experiment. Improving upon that, a 1D surface mixing model is proposed to capture the dynamics in the implantation layer. This model is validated with experimental data [3] which measured stoichiometric ratio Si/C as a function of depth in the implantation layer which can be captured using a 1D model.

[1] Younkin et al Computer Physics Communications 2019

[2] Rudakov et al Physica Scripta 2020

[3] Sinclair et al 2021 Nuclear Materials and Energy