Effect of the angle of incidence of He, T, and D ions irradiation on physical and chemical sputtering of graphite targets in the near sputtering threshold energy regime

• Erosion is Angle Dependent: Maximum erosion (physical and chemical sputtering) occurs at grazing angles (60°- 80°). • Impact of Atomic Displacements: Chemical sputtering was found to be influenced by the kinetic part of radiation damage. • Chemical Sputtering Has Dual Thresholds: Chemical erosion starts with bond breaking at 5eV, and rises with physical displacement. • Implications for Fusion Reactors: The findings emphasize the importance of incident angle and ion energy in graphite erosion. This study presents a comprehensive Monte Carlo simulation-based investigation into the angle of incidence dependence of physical and chemical sputtering of graphite targets irradiated by He + , T + , and D + ions in the near-threshold energy regime. This investigation has been executed by utilizing two advanced simulation codes, RDS-BASIC and SDTrimSP. In this study, we assess sputtering yields and energy thresholds across incidence angles ranging from 0° to 80°. Results indicate that physical sputtering yields are maximized at grazing angles (60°–80°), accompanied by a systematic decrease in sputtering threshold energy with increasing angle. In contrast, chemical sputtering, modeled for T + and D + ions, reveals a two-step threshold behavior: an initial erosion onset at ∼ 5 eV, and a secondary enhancement between 8–13 eV driven by physical displacement effects. Which also was found to influence the angle og incidence dependence of the chemical sputtering. Thereby, to physical sputtering, chemical erosion exhibits a peak at intermediate angles (60°–70°). These findings offer key insights into the erosion mechanisms of plasma-facing components and support the optimized design of carbon-based materials for future nuclear fusion reactor applications.