Spatial analysis of impurities on the surface of flange and optical window of the tokamak using laser induced breakdown spectroscopy

• Identification of constituents of impurity layer on the surface of optical window and flange of Aditya tokamak.
• Spatial distribution of impurities on the optical window of the tokamak.
• Variation of spectral intensities of constituents with radial distance and color.
• Relative variation of spectral intensity of impurity constituents.

Laser induced breakdown spectroscopy (LIBS) spectra of optical window and flange of Aditya tokamak have been recorded in the spectral range of 200–500 nm in open atmosphere. For qualitative analysis of these samples, the intensity variation of elemental impurities (Fe, Cr, Ni, Mn, Mo, Cu and C) on the surface of optical window and flange with radial distance has been studied. Depending on thickness of thin films of impurity, four different concentric color rings are observed on the surface of the flange. On moving from reddish brown to indigo color ring, the trends in spectral intensity of these impurities are found in decreasing order. Comparative spectral intensity variation of impurities in both the samples reveals that the impurity deposition on the flange surface is more in comparison to the optical window. Our study demonstrates the capability of LIBS to analyze the spatial distribution of deposited impurities on window and flange samples.