High-velocity dust impacts in plasma facing materials: Insights from molecular dynamics simulations

In fusion reactors, the integrity of plasma-facing components is critically challenged by high-velocity tungsten (W) dust impacts, particularly during events like runaway electron terminations [1]. These incidents can propel dust particles at velocities potentially exceeding several km/s, leading to severe material erosion and damage. Current models predominantly address only low-velocity impacts, revealing a significant gap in our understanding necessary for reactors such as ITER and DEMO [2]. To address this, our study employs large-scale molecular dynamics (MD) simulations to investigate the effects of high-velocity dust impacts on W walls. We analyze a broad range of impact velocities (2.5 to 4.5 km/s), angles (0° to 75°), and temperatures (300 to 3000 K). Our simulations, incorporating up to 300 million atoms, highlight how the impact angle and temperature predominantly dictate the morphology of impact craters and the distribution of ejecta. The detailed examination of sputtering, degradation, and deformation mechanisms provides crucial insights into the atomic-level dynamics of dust-wall interactions. Further, our MD results are in excellent agreement with experimental findings, affirming the reliability of the simulation approach. This research significantly advances our understanding and capability to design more resilient and efficient materials for future fusion energy systems [3-5].

References

[1] M. De Angeli et al. Nuclear Fusion, 63, 1 (2022)

[2] S. Ratynskaia et al. Reviews of Modern Plasma Physics. 6, 1 (2022).

[3] A. Fraile, et al. Analysis of hypervelocity impacts: The tungsten case. Nuclear Fusion. 62, 2 (2022)

[4] P. Dwivedi et al. Journal of Nuclear Materials. 594, 155042 (2024)

[5] P. Dwivedi et al. Journal of Nuclear Materials. 600, 155289 (2024)