Laser-induced breakdown spectroscopic characterization of impurity deposition on the first wall of a magnetic confined fusion device: Experimental Advanced Superconducting Tokamak

•LIBS is proposed as an in-situ diagnostic technique to monitor impurities on PFCs.•The depth profile of the deposited layer is explored by the LIBS technique.•The effect of ambient pressure at the LIBS signal is studied.•Linear correlation method is applied to determine the thickness of deposited layer.

Our recent investigations have indicated the potential of laser-induced breakdown spectroscopy (LIBS) for analysis of the co-deposited layers on the first wall in the Experimental Advanced Superconducting Tokamak (EAST) in the vacuum environment. Detailed information of compositions at the superficial and in-depth positions of the first wall of divertor tiles can be obtained by analyzing the spectra from 200 to 980 nm. The decrease in concentrations of the depositional elements (such as D, Li) was clearly observed in the depth from 0 to 100 μm, but the concentrations of the substrate elements were found to be relatively uniform in the depth after dozens of laser pulses. The linear correlation approach has been applied for improving the impurity depth profile accuracy and identifying the interface boundary between the deposition layer and the substrate for the first time. This would help us to develop LIBS technique to monitor the fuel retention and impurity deposition on the first wall of EAST.