Development of an <i>in situ</i> diagnostic system for mapping the deposition distribution on plasma facing components of the HL-2M tokamak

Cai, Laizhong; Wang, Zhenzhong; Li, Cong; Huang, Xiangmei; De-you, Zhao; Ding, Hongbin

doi:10.1063/1.5082630

Cited by 13 publications

(4 citation statements)

References 13 publications

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“…Moreover, LIBS also has great potential for depth analysis of multilayer samples based on laser ablation and atomic emission spectroscopy [10]. With these special benefits, LIBS had been installed in several tokamak devices and proposed for future application in W7-X for PWI research including fuel retention and erosion/deposition studies [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Quantification of erosion pattern using picosecond-LIBS on a vertical divertor target element exposed in W7-X

De-you¹,

Yi²,

Eksaeva³

et al. 2020

Nucl. Fusion

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A set of dedicated marker samples consisting of fine-grain graphite as substrate, an interlayer of 0.2–0.4 μm molybdenum (Mo) employed as marker, and a 5–10 μm thick carbon (C) marker layer on top were installed in Wendelstein 7-X (W7-X) to investigate locally the C erosion and deposition. In this study, a set of five individual marker tiles, installed in a vertical divertor element of the test divertor unit in half-module 50, and exposed to about 40 min of plasma predominant in the standard magnetic divertor configuration in the first year of divertor operation in W7-X (OP1.2A), were retrieved from the vessel for post-mortem analysis. Picosecond laser induced breakdown spectroscopy (ps-LIBS) was applied on these marker tiles in order to determine the local erosion/deposition pattern caused by plasma impact. The general erosion/deposition pattern on the vertical target element was studied with the aid of depth-profiling by Mo line emission due to ps-LIBS with the number of applied laser pulses (355 nm, 2.3 J cm−2, 35 ps) at one probing location. Several potential asymmetry factors which avoid a perfect layer-by-layer ablation process in the laser ablations are proposed and discussed when a rough layered structure sample with a rough surface is analysed by the ps-LIBS technique. Thereby, a simulation model was developed to correct the measurement error of the ps-LIBS method caused by the non-perfect rectangle profile of the applied laser beam. The depth resolution of the applied ps-LIBS system was determined by quantification of the laser ablation rates of the different layers and the C substrate which were measured utilising profilometry and cross comparison with the thicknesses of the C and Mo marker layers determined by a combined focused ion beam and scanning electron microscopy technique. For the first time, the erosion/deposition pattern on the vertical target was mapped and quantified by ps-LIBS technique. A relatively wide net erosion zone with a poloidal extend of about 200 mm was identified which can be correlated to the main particle interaction zone at the magnetic strike-line of the dominantly applied standard magnetic divertor configuration. At the position of peak erosion, not only 7.6 × 1019 C atoms/cm2 but also 2 × 1018 Mo atoms/cm2 which results can be extrapolated to total 15 × 1019 C atoms/cm2, were eroded due to plasma fuel particle (H, He) and impurity (O, C) ion impact.

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Section: Introductionmentioning

confidence: 99%

Quantification of erosion pattern using picosecond-LIBS on a vertical divertor target element exposed in W7-X

De-you¹,

Yi²,

Eksaeva³

et al. 2020

Nucl. Fusion

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“…Another study outlined an in situ diagnostic for mapping the deposition distribution (IMap) on plasma facing components for assessing material deposition and fuel retention. 172 The IMap system was built using LIBS and was capable of remote scanning and automatic adjustment of lenses, mirrors and fibres to enable measurement of wall properties over a wide area. Hydrogen and deuterium, along with elements with emission lines between 380 and 850 nm could be identified, along with depth profiles and fuel retention.…”

Section: Inorganic Chemicals and Materialsmentioning

confidence: 99%

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

Carter

Clough

Fisher

et al. 2020

J. Anal. At. Spectrom.

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“…Laser-induced breakdown spectroscopy (LIBS) is a promising technique for elemental analysis. Its advantages of high analytical speed, low cost, simultaneous multi-elemental capacity, in-situ, and real-time analysis ability make it suitable for a wide field of applications, such as space exploration [1], environmental monitoring [2], energy [3], biomedicine [4], and other fields [5][6][7][8]. The use of LIBS in coal quality analysis has also been studied for several years.…”

Section: Introductionmentioning

confidence: 99%

Accuracy Enhancement of LIBS-XRF Coal Quality Analysis Through Spectral Intensity Correction and Piecewise Modeling

Bai

Zhang³

et al. 2022

Front. Phys.

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The combination of laser-induced breakdown spectroscopy and energy dispersive X-ray fluorescence spectroscopy in the coal quality analysis was reported formerly. But in the practical test of the prototype instrument in the real power plant, the X-ray fluorescence signals suffered from intensity fluctuations over long-time measurements. The long-term signal fluctuations cause lower efficiency on the establishment of the calibration model and relatively larger root-mean-squared error of prediction (RMSEP) for unknown samples. Therefore, the spectral intensity correction was performed in the measurements; a randomly selected sample was measured several times in the whole measurements, including the modeling samples and unknown samples, recording the signal fluctuations and searching for a set of factors suitable for the intensity correction of a full-spectrum–based partial least square calibration model. In addition, as the signals of the coal samples of the power plant showed the potential of classification, the piecewise models were also established in case of further enhancement of the model or prediction accuracy. The RMSEPs of the calorific value, ash, volatile, and sulfur were lowered from 0.68 MJ/kg, 1.62%, 0.32%, and 0.24% to 0.51 MJ/kg, 1.34%, 0.16%, and 0.14% after spectral intensity correction, respectively. The piecewise modeling with spectral intensity correction achieved similar RMSEP for volatile and sulfur prediction but with more accurate models. The spectral intensity correction showed the ability to reduce the long-term signal fluctuation, and piecewise modeling also showed more efficiency in the model establishments for volatile and ash determination.

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Development of an in situ diagnostic system for mapping the deposition distribution on plasma facing components of the HL-2M tokamak

Cited by 13 publications

References 13 publications

Quantification of erosion pattern using picosecond-LIBS on a vertical divertor target element exposed in W7-X

Quantification of erosion pattern using picosecond-LIBS on a vertical divertor target element exposed in W7-X

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

Accuracy Enhancement of LIBS-XRF Coal Quality Analysis Through Spectral Intensity Correction and Piecewise Modeling

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