Investigation of Debris Mitigation in Droplet-Based Terbium Plasma Sources Produced by Laser Ablation Under Varying Buffer Gas Pressures

The fragment suppression ability of terbium plasma generated by laser at different environmental pressures is investigated, with a focus on exploring the slowing effect of buffer gas on high-energy particles. Using two-dimensional radiation hydrodynamic simulations with the FLASH code, this study evaluates the debris mitigation efficiency of terbium plasma across a range of buffer gas pressures (50–1000 Pa). Key findings reveal that helium buffer gas exhibits a nonlinear pressure-dependent response in plasma dynamics and debris suppression. Specifically, at 1000 Pa helium, the plasma shockwave stops within stopping distance xst = 12.13 mm with an attenuation coefficient of b = 0.0013 ns−1, reducing radial expansion by 40% compared to 50 Pa (xst = 23.15 mm, b = 0.0010). This pressure scaling arises from enhanced collisional dissipation, confining over 80% of debris kinetic energy below 200 eV under 1000 Pa conditions. In contrast, argon exhibits superior stopping power within ion energy domains (≤1300 eV), attaining a maximum stopping power of 2000 eV·mm−1 at 1300 eV–a value associated with a 6.4-times-larger scattering cross-section compared to helium under equivalent conditions. The study uncovers a nonlinear relationship between kinetic energy and gas pressure, where the deceleration capability of buffer gases intensifies with increasing kinetic energy. This work demonstrates that by leveraging argon’s broadband stopping efficiency and helium’s confinement capacity, debris and high energy ions can be effectively suppressed, thereby securing mirror integrity and source efficiency at high repetition rates.