Deuterium detection and quantification by laser-induced breakdown spectroscopy and calibration-free analysis in ITER relevant samples

Tritium (T) inventory in Plasma Facing Components (PFCs) will be one of the critical issues for ITER because of the impact tritium can have on the machine operation and safety. Laser Induced Breakdown Spectroscopy (LIBS) is a promising technique to accomplish this task, providing both qualitative and quantitative composition of the chemical elements retained in PFCs. LIBS does not require sample pretreatment or manipulation, it can work in-situ between fusion discharges or during maintenance periods, it is suitable for measurements at different residual pressures, with different background gases. It can detect all the chemical elements through their spectral emission. This paper presents the results of LIBS measurements at 100 mbar nitrogen pressure on metallic coating (W-Al-D) simulating the superficial composition of ITER divertor PFCs contaminated with nuclear fuel and material eroded from the first wall. LIBS spectra showed clear W, Al, D emission lines. A quantitative estimation of their relative concentration was performed by applying the Calibration Free (CF) analysis. CF does not require reference samples, so ifs particularly suitable for this purpose. CF results were compared with the nominal concentrations and were found in good agreement with the latter.