Resonant Laser Induced Breakdown Spectroscopy for quantitative elemental depth profile analysis of WTa coating

This work reports on the procedure of Resonant-LIBS, in which ablation and subsequent excitation is achieved by fine-tuning an Optical Parametric Oscillator (OPO) laser to the resonant transition of tungsten (W I) at 255.14 nm and analyzing the optical emission spectroscopy results. Compared to conventional LIBS, the ablation rate is significantly reduced in the resonant regime, resulting in finer resolution of depth profiles. This reduction in ablation rate can be attributed to a process called Resonance Laser Ablation (RLA) where a part of the laser energy is employed for ablation, while the rest is dedicated to resonant excitation. The sample under consideration is a WTa-coated (7 mu m) Mo substrate prepared by a dual magnetron sputtering system. These efforts are motivated by the need for improvement in quantitative depth analysis of W-based Plasma-Facing Components (PFC). Particularly to target the undesirable surface modifications due to the interaction with H isotopes in fusion plasma, such as fuel retention or erosion/deposition.