Temporal and spatial dynamics of optical emission from laser ablation of the first wall materials of fusion device

De-you, Zhao; Liu, Cong; Wang, Yong; Wang, Zhiwei; Gao, Liang; Hu, Zhenhua; Wu, Jing; Luo, Guang-Nan; Ding, Hongbin

doi:10.1088/2058-6272/aa96a0

Cited by 8 publications

(5 citation statements)

References 30 publications

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“…Note that the units of w d and λ c in equation ( 10) are nm. According to our previous work, the v 0 of W I, Mo I and C II were about 16 km s −1 , 19 km s −1 and 30 km s −1 , respectively [41]. When the spectrum is collected in coaxial with the laser as shown in figure 1, the wavelength shift estimated by equation ( 9) of W, Mo and C were 0.027 nm, 0.035 nm and 0.066 nm, respectively.…”

Section: Influence Of Spectral Profile Broadening Mechanism On Magnet...mentioning

confidence: 59%

“…In our previous work, the temporal evolution of N e of W, Mo and C has been systematically studied [31,32]. Consequently, the gate delays for W, Mo and C were set to 400 ns, 500 ns and 250 ns according to the characteristics of the sample itself, respectively [41]. Under this condition, the Stark broadening of three elements were less than 0.008 nm, which is smaller than the instrument broadening.…”

Section: Influence Of Spectral Profile Broadening Mechanism On Magnet...mentioning

confidence: 99%

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A potential optical approach for diagnosis of the local magnetic field near the surface of the first wall/divertor tiles by Zeeman effect using polarization-resolved laser-induced breakdown spectroscopy

Wu,

et al. 2024

Nucl. Fusion

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Magnetic field measurement is the basic diagnosis to obtain the physical engineering parameters of magnetic confinement fusion device and the macro information of plasma discharge. The real-time diagnosis of magnetic field distribution near the plasma-facing components (PFCs) surface provides the important information on the migration and transport model of key elements. In this work, a remote, in-situ approach for the magnetic field measurement near the surface of PFCs by the polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) based on Zeeman effect is proposed and implemented. The Zeeman characteristics of the emission spectra of laser-induced W, Mo and C plasmas were verified in the laboratory by using different magnetic field configurations. According to the polarization characteristics of the Zeeman sublines of the LIBS spectrum, the intensity and direction of the external local magnetic field were successively identified by using a linear polarizer. Subsequently, a linear array fiber was utilized to determine the polarity of the external magnetic field. And finally, the magnetic field intensity near the lower edge surface of the tungsten baffle of the EAST upper divertor was measured when the field coils were demagnetized. This method can supplement the experimental data near the PFCs for the magnetic field configuration of the magnetic confinement fusion device and provide a reference for the wall element analysis model diagnosed by LIBS.

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Section: Influence Of Spectral Profile Broadening Mechanism On Magnet...mentioning

confidence: 59%

Section: Influence Of Spectral Profile Broadening Mechanism On Magnet...mentioning

confidence: 99%

A potential optical approach for diagnosis of the local magnetic field near the surface of the first wall/divertor tiles by Zeeman effect using polarization-resolved laser-induced breakdown spectroscopy

Wu,

et al. 2024

Nucl. Fusion

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“…The notable advantages of LIBS over common techniques available for elemental analysis, such as secondaryion mass spectrometry, inductively coupled plasma-optical emission spectroscopy/mass spectrometry and REM-EDX (Raster Electron Microscopic with Energy Dispersive X-ray detection), are suitability for in situ analysis, all-optical contact and real-time data collection. Due to these advantages, LIBS has been extensively used in the fields of public security [12][13][14], industrial monitoring [15][16][17][18][19], deep-sea exploration [20], environmental monitoring [21], etc. Recently, its application as an innovative method for in situ estimation of the surface hardness of a solid material has been constructed and validated [22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Estimating the grain size of microgranular material using laser-induced breakdown spectroscopy combined with machine learning algorithms

ZHANG 张,

LI 李,

YANG 杨

et al. 2024

Plasma Sci. Technol.

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Recent work validated a new method for estimating grain size of microgranular materials in the range of tens-to-hundreds micrometers using laser-induced breakdown spectroscopy (LIBS). In that situation, univariate analysis was performed and a piecewise model has to be constructed for achieving the estimation of the grain size within such a wide range. This is due to the fact that a complex dependence of plasma formation environment (i.e., the status of luminous plasma and therefore LIBS signal to be measured) on grain size occurs in the size range studied there. In the present work, we tentatively construct a unified calibration model suitable for LIBS-based estimation of those grain sizes. Specifically, two unified multivariate calibration models are constructed based on back-propagation neural network (BPNN) algorithms using the feature selection strategies with and without considering physical prior knowledge, respectively. By detailed analysis of the performances of the two multivariate models, it was found that, a unified calibration model can be constructed successfully based on BPNN algorithms for estimating the grain size in the range of tens-to-hundreds micrometers. It was also found that this model constructed with a physics-guided feature selection strategy has better prediction performances. This study has practical significance in developing the technology for material analysis using LIBS, especially in the case that LIBS signal exhibits a complex dependence on the material parameter to be estimated.

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“…As a diagnosis system, LIBS has a flexible design and can be integrated into all kinds of devices or production lines. According to the literature [19][20][21], LIBS has been used in the tokamak device's first wall composition monitoring applications where the test environment is relatively severe, so there is reason to expect the application of LIBS in exhaust gas monitoring.…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis and time-resolved characterization of simulated tokamak exhaust gas by laser-induced breakdown spectroscopy

He¹,

Xu²,

Zhang³

et al. 2022

Plasma Sci. Technol.

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Tokamak exhaust is an important part of the deuterium-tritium fuel cycle system in fusion reaction. In this work, we present a laser-induced breakdown spectroscopy (LIBS) based method to monitor the gas compositions from exhaust system in the Tokamak device. Helium (He), a main impurity in the exhaust gas, was mixed with hydrogen (H2) in different ratios through a self-designed gas distribution system, and sealed into a measurement chamber as a standard specimen. A 532 nm wavelength laser pulse with an output power of 100 mJ was used for plasma excitation. The time-resolved LIBS is used to study the time evolution characteristics of the signal strength, signal-to-background-ratio (SBR), signal-to-noise-ratio (SNR) and relative standard deviation (RSD) of the helium and hydrogen characteristic lines. The Boltzmann two-line method was employed to estimate the plasma temperature of laser-induced plasma (LIP). The Stark-broadened profile of He I 587.56 nm was exploited to measure the electron density. From these studies, an appropriate time was determined in which the low RSD% were consistent with the high signal-to-noise ratio. The He I 587.56 nm and Hα emission lines with good signal-to-noise ratio were extracted from the spectrum and used in the external standard method and internal standard method for quantitative analysis. The test results for mixed gas showed that the average relative error of prediction was less than 11.15%, demonstrating the great potential of LIBS in detecting impurities in plasma exhaust gas.

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Temporal and spatial dynamics of optical emission from laser ablation of the first wall materials of fusion device

Cited by 8 publications

References 30 publications

A potential optical approach for diagnosis of the local magnetic field near the surface of the first wall/divertor tiles by Zeeman effect using polarization-resolved laser-induced breakdown spectroscopy

A potential optical approach for diagnosis of the local magnetic field near the surface of the first wall/divertor tiles by Zeeman effect using polarization-resolved laser-induced breakdown spectroscopy

Estimating the grain size of microgranular material using laser-induced breakdown spectroscopy combined with machine learning algorithms

Quantitative analysis and time-resolved characterization of simulated tokamak exhaust gas by laser-induced breakdown spectroscopy

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