Ambient gas; Magnetic field; LIBS; EAST; ICRF wall cleaning;TRANSVERSE MAGNETIC-FIELD; INDUCED PLASMA SPECTROSCOPY; OPTICAL-EMISSION; PLUME; PERFORMANCE

In this paper, laser-induced breakdown spectroscopy (LIBS) under magnetic field condition has been studied in laboratory and EAST tokamak. The experimental results reveal that in helium ambient gas, the magnetic field significantly enhances the LIBS signal intensity (similar to 3 times). The effect of time delay and laser fluence on the intensity of LIBS has been investigated for optimizing the signal to background ratio (S/B). The developed LIBS approach has been applied to monitor the cleaning performance of the first wall in the fusion device of EAST using the ion cyclotron range of frequency (ICRF). The experimental results demonstrate that the cleaning performance for Li/D co-deposition layer is effective under helium ambient gas. The removing rate of Li on the surface of W tile is faster than that on Mo tile in He-ICRF cleaning and the D/(D + H) ratio on Mo tile is higher by similar to 1.2 times than that on W tile. This work would indicate the feasibility of using LIBS to monitor the wall cleaning processes in EAST tokamak. (C) 2017 Elsevier B.V. All rights reserved.

LiSn alloy; CF LIBS; Surface analysis; Fusion; Liquid metal;LASER-INDUCED-BREAKDOWN; LIQUID LITHIUM; SPECTROSCOPY; DIAGNOSTICS; PLASMAS; LEAD

The difference between the composition of the surface and the inner part of the LiSn sample was studied using Calibration Free Laser Induced BreakdownSpectroscopy (CF-LIBS) method. The sample was analysed under the low pressure (1330 Pa) in Ar atmosphere. The spectra were record using Echelle spectrometer (Mechelle ME5000). Gate delay and gate width was optimised and set to 300 ns. In order to analyse depth profile the LIBS spectra was recorded after each laser shot. The electron density analysed by laser induced plasma was determined separately for each laser shot, which means for each ablated layer of investigated sample. The difference between the individual shots taken at distinct sites of the sample are shown. The CF-LIBS method was used to determine the elemental composition near the surface and in the central part of the LiSn sample. (C) 2016 Published by Elsevier B.V.

ITER relevant coatings; Laser induced breakdown spectroscopy; (LIBS) diagnostics; Ablation rate; Surface morphology;TILES; JET

Laser induced breakdown spectroscopy (LIBS) has been applied to study ITER-relevant coatings with different surface morphology and crystallinity. LIBS elemental depth profiles were compared with those obtained by secondary ion mass spectrometry (SIMS). Depending on surface morphology and crystallinity, the laser ablation rate of the coatings changed by an order of magnitude, the highest ablation rate had samples prepared by thermoionic vacuum discharge. The inclusion of aluminum (proxy for beryllium) increased the ablation rate by a factor of >6. In addition, for W-Al coatings the ablation was non-stoichiometric. (C) 2017 Elsevier B.V. All rights reserved.