Development of laser-induced breakdown spectroscopy for analyzing deposited layers in ITER

Laser-induced breakdown spectroscopy (LIBS) experiments on different ITER-relevant beryllium-tungsten mixtures were performed to develop LIBS for tokamak applications. Some of the samples were doped or implanted with deuterium to simulate fuel retention. The results indicate that beryllium and tungsten have a number of distinguishable spectral lines for diagnostics purposes, but detection of deuterium is challenged by its low concentration and low fluences used. By studying the depth profiles of the coatings, the removal rates of the layers were observed to depend on the thickness, composition and deuterium content of the coating. Quantitative studies of the compositions were made by calibration-free LIBS, and the results agreed well with those given by ion-beam methods.