Integrated core-SOL modelling of JET baseline plasmas: the role of ELMs on Tungsten sputtering

At JET an experimental campaign in D-T (DTE2) was conducted in 2021 using a Beryllium(Be)-Tungsten(W) ITER-like wall (ILW) which increased significantly scenario complexities due to high-Z impurities accumulation which could lead to plasma disruptions. To achieve high-performance plasmas, two complementary scenarios were developed: the baseline scenario and the hybrid scenario. This study aims to characterize the sputtering of W in the baseline scenario of DTE2 (I_P ≥ 3.5 MA, β_N ∼ 1.8, q₉₅ ∼ 4)[1], considering: i) different isotopic mixtures for the main gas (D, T, and a 50\%-50\% D-T mix), and ii) the impact of ELMs dynamics in the inter- and intra-ELM phases. The study employed an integrated modelling approach core+edge+SOL using the JINTRAC suite of codes[2]. Initial results indicated significantly higher sputtering for Tritium compared to Deuterium and the D-T mixture. The study reveals the possibility for Tritium plasmas that the influx of W through the separatrix during an ELM, significantly exceeds the outgoing flux, with a consequent dangerous accumulation of impurities into the core. These results are currently under study for potential confirmation through transport studies and parameter scans. In the JINTRAC simulations, Be and W were initially prioritized as impurities; subsequently, the analysis extended to include the contribution of Nickel to the sputtering.

[1] L. Garzotti et al., Nuclear Fusion 59(7), 076037 (2019)

[2] M. Romanelli et al., Plasma and Fusion research 9, 3403023 (2014)