LIBS measurement of trace tantalum and rhenium in tungsten for in-situ diagnostic of nuclear transmutation

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) was applied to tungsten (W)- tantalum (Ta) alloy and W-rhenium (Re) alloy. In the W-Ta alloy measurement, an apparent Ta I line at 648.5 nm was found to be isolated from W I lines and used for the concentration determination. Accurate concentration measurements were achieved for a W - 2 at.% Ta specimen at the ambient gas pressure between 0.1 and 10 Torr of He, Ne and Ar gas. Within these ambient gas species, the highest line intensities were obtained by Ar gas. In the W-Re alloy measurement, the detection limit of trace Re in W-Re was investigated. CF-LIBS results agree well with the nominal concentration of Re down to W-0.5 at.% Re specimen which is better than the measurement accuracy of EDX (energy-dispersive X-ray micro-analysis). Further improvements are required in order to measure 0.2 at.% Re in W expected at ITER. (C) 2019 Elsevier B.V. All rights reserved.