LIBS depth profiling of Be-containing samples with different gaseous impurity concentrations

Understanding the interaction between the fusion plasma and the plasma-facing materials (PFMs) is crucial for achieving the optimal performance, safety, and lifetime of the fusion devices. Relevant materials have been intensely studied to determine fuel retention and the composition of the co-deposited layers on the PFMs by depth profile analysis using Laser-Induced Breakdown Spectroscopy (LIBS) and Calibration-Free (CF)-LIBS. However, the comparison between the layers containing a mixture of different (seeding) gases using LIBS, has not been studied systematically. Consequently, the aim of this work is the LIBS depth profile analysis of Be-based samples containing the fuel (D) and one of the seeding gases (N, Ne, He) with variable concentrations to study the potential impact on fuel retention in the PFMs. The LIBS measurements were performed using Nd:YAG laser (1064 nm) under Ar atmosphere (at 2 and 100 mbar). In LIBS the ablation rate was evaluated, spectral lines of all relevant elements except N and Ne were detected and compared with the SIMS depth profiles. The reasons for the non-detectability of Ne are discussed in detail.