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A theoretical study of the signal enhancement mechanism of coaxial DP-LIBS
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作者 宋震 王俊霄 +11 位作者 王钢 张雷 王树青 张婉飞 马晓飞 刘珍荣 罗学彬 马维光 叶泽甫 朱竹君 尹王保 贾锁堂 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第5期156-164,共9页
In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectra... In the field of dual-pulse laser-induced breakdown spectroscopy(DP-LIBS)research,the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectral signal enhancement is paramount.To aid researchers in identification of optimal signal enhancement conditions and more accurate interpretation of the underlying signal enhancement mechanisms,theoretical simulations of the spatiotemporal processes of coaxial DP-LIBS-induced plasma have been established in this work.Using a model based on laser ablation and two-dimensional axisymmetric fluid dynamics,plasma evolutions during aluminum–magnesium alloy laser ablation under single-pulse and coaxial dualpulse excitations have been simulated.The influences of factors,such as delay time,laser fluence,plasma temperature,and particle number density,on the DP-LIBS spectral signals are investigated.Under pulse intervals ranging from 50 to 1500 ns,the time evolutions of spectral line intensity,dual-pulse emission enhancement relative to the single-pulse results,laser irradiance,spatial distribution of plasma temperature and species number density,as well as laser irradiance shielded by plasma have been obtained.The study indicates that the main reason behind the radiation signal enhancement in coaxial DP-LIBS-induced plasma is attributed to the increased species number density and plasma temperature caused by the second laser,and it is inferred that the shielding effect of the plasma mainly occurs in the boundary layer of the stagnation point flow over the target surface.This research provides a theoretical basis for experimental research,parameter optimization,and signal enhancement tracing in DP-LIBS. 展开更多
关键词 laser-induced plasma radiation fluid dynamics model double pulse laser-induced breakdown spectroscopy(DP-LIBS) laser ablation signal enhancement mechanism
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Development of miniaturized SAF-LIBS with high repetition rate acousto-optic gating for quantitative analysis
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作者 陈斐 侯佳佳 +10 位作者 王刚 赵洋 李佳轩 王树青 张雷 张婉飞 马晓飞 刘珍荣 罗学彬 尹王保 贾锁堂 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第1期157-164,共8页
The self-absorption effect in laser-induced breakdown spectroscopy(LIBS)reduces the accuracy of quantitative measurement results.The self-absorption-free LIBS(SAF-LIBS)has been proved to directly capture the optically... The self-absorption effect in laser-induced breakdown spectroscopy(LIBS)reduces the accuracy of quantitative measurement results.The self-absorption-free LIBS(SAF-LIBS)has been proved to directly capture the optically thin plasma spectra by setting an appropriate exposure time.In this work,a novel SAF-LIBS technique with high repetition rate acousto-optic gating is developed,in which an acousto-optic modulator is used as the shutter to diffract the optically thin fluorescence,and a high repetition rate laser is used to produce quasi-continuous plasmas to enhance the integral spectral intensity,so that the CCD spectrometer can replace an intensified CCD(ICCD)and echelle spectrometer in SAF-LIBS.Experimental results show that the average absolute prediction error of aluminum is reduced to 0.18%,which is equivalent to that of traditional SAF-LIBS.This technique not only effectively shields continuous background radiation and broadened spectral lines in optically thick plasma,but also has advantages of miniaturization,low cost,convenience and reliability. 展开更多
关键词 self-absorption-free LIBS(SAF-LIBS) self-absorption effect optically thin plasma high repetition rate laser acousto-optic gating
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Mechanisms and efficient elimination approaches of self-absorption in LIBS 被引量:5
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作者 Jiajia HOU Lei ZHANG +7 位作者 Yang ZHAO Zhe WANG Yong ZHANG Weiguang MA Lei DONG wangbao yin Liantuan XIAO Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第3期125-139,共15页
Laser-induced breakdown spectroscopy(LIBS) is a promising analytical spectroscopy technology based on spectroscopic analysis of the radiation emitted by laser-produced plasma.However, for quantitative analysis by LIBS... Laser-induced breakdown spectroscopy(LIBS) is a promising analytical spectroscopy technology based on spectroscopic analysis of the radiation emitted by laser-produced plasma.However, for quantitative analysis by LIBS, the so-called self-absorption effects on the spectral lines, which affect plasma characteristics, emission line shapes, calibration curves, etc, can no longer be neglected. Hence, understanding and determining the self-absorption effects are of utmost importance to LIBS research. The purpose of this review is to provide a global overview of self-absorption in LIBS on the issues of experimental observations and adverse effects,physical mechanisms, correction or elimination approaches, and utilizations in the past century.We believe that better understanding and effective solving the self-absorption effect will further enhance the development and maturity of LIBS. 展开更多
关键词 LASER-INDUCED BREAKDOWN spectroscopy(LIBS) SELF-ABSORPTION effect optically thin ELEMENTAL analysis
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Elemental and proximate analysis of coal by x-ray fluorescence assisted laser-induced breakdown spectroscopy 被引量:4
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作者 Zhihui TIAN Xiaolin LI +9 位作者 Gang WANG Lei ZHANG Jiaxuan LI Shuqing WANG Yu BAI Wanfei ZHANG Han YUE Xiaofei MA wangbao yin Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第8期55-63,共9页
Although laser-induced breakdown spectroscopy(LIBS),as a fast on-line analysis technology,has great potential and competitiveness in the analysis of chemical composition and proximate analysis results of coal in therm... Although laser-induced breakdown spectroscopy(LIBS),as a fast on-line analysis technology,has great potential and competitiveness in the analysis of chemical composition and proximate analysis results of coal in thermal power plants,the measurement repeatability of LIBS needs to be further improved due to the difficulty in controlling the stability of the generated plasmas at present.In this paper,we propose a novel x-ray fluorescence(XRF) assisted LIBS method for high repeatability analysis of coal quality,which not only inherits the ability of LIBS to directly analyze organic elements such as C and H in coal,but also uses XRF to make up for the lack of stability of LIBS in determining other inorganic ash-forming elements.With the combination of elemental lines in LIBS and XRF spectra,the principal component analysis and the partial least squares are used to establish the prediction model and perform multi-elemental and proximate analysis of coal.Quantitative analysis results show that the relative standard deviation(RSD) of C is 0.15%,the RSDs of other elements are less than 4%,and the standard deviations of calorific value,ash content,sulfur content and volatile matter are 0.11 MJ kg,0.17%,0.79% and 0.41%respectively,indicating that the method has good repeatability in determination of coal quality.This work is helpful to accelerate the development of LIBS in the field of rapid measurement of coal entering the power plant and on-line monitoring of coal entering the furnace. 展开更多
关键词 laser-induced breakdown spectroscopy(LIBS) x-ray fluorescence spectrometry(XRF) high repeatability measurement spectral calibration instability analysis
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Accurate quantitative CF-LIBS analysis of both major and minor elements in alloys via iterative correction of plasma temperature and spectral intensity 被引量:4
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作者 Shuxia ZHAO Lei ZHANG +6 位作者 Jiajia HOU Yang ZHAO wangbao yin Weiguang MA Lei DONG Liantuan XIAO Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第3期106-111,共6页
The chemical composition of alloys directly determines their mechanical behaviors and application fields.Accurate and rapid analysis of both major and minor elements in alloys plays a key role in metallurgy quality co... The chemical composition of alloys directly determines their mechanical behaviors and application fields.Accurate and rapid analysis of both major and minor elements in alloys plays a key role in metallurgy quality control and material classification processes.A quantitative calibration-free laser-induced breakdown spectroscopy(CF-LIBS)analysis method,which carries out combined correction of plasma temperature and spectral intensity by using a secondorder iterative algorithm and two boundary standard samples,is proposed to realize accurate composition measurements.Experimental results show that,compared to conventional CF-LIBS analysis,the relative errors for major elements Cu and Zn and minor element Pb in the copperlead alloys has been reduced from 12%,26%and 32%to 1.8%,2.7%and 13.4%,respectively.The measurement accuracy for all elements has been improved substantially. 展开更多
关键词 spectral intensity plasma temperature iterative correction calibration-free laserinduced breakdown spectroscopy(CF-LIBS)
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Measurement and analysis of species distribution in laser-induced ablation plasma of an aluminum–magnesium alloy 被引量:2
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作者 Junxiao WANG Shuqing WANG +6 位作者 Lei ZHANG Maogen SU Duixiong SUN Qi MIN Weiguang MA wangbao yin Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第3期51-60,共10页
We proposed a theoretical spatio-temporal imaging method,which was based on the thermal model of laser ablation and the two-dimensional axisymmetric multi-species hydrodynamics model.By using the intensity formula,the... We proposed a theoretical spatio-temporal imaging method,which was based on the thermal model of laser ablation and the two-dimensional axisymmetric multi-species hydrodynamics model.By using the intensity formula,the integral intensity of spectral lines could be calculated and the corresponding images of intensity distribution could be drawn.Through further image processing such as normalization,determination of minimum intensity,combination and color filtering,a relatively clear species distribution image in the plasma could be obtained.Using the above method,we simulated the plasma ablated from Al-Mg alloy by different laser energies under 1 atm argon,and obtained the theoretical spatio-temporal distributions of Mg I,Mg II,Al I,Al II and Ar I species,which are almost consistent with the experimental results by differential imaging.Compared with the experimental decay time constants,the consistency is higher at low laser energy,indicating that our theoretical model is more suitable for the plasma dominated by laser-supported combustion wave. 展开更多
关键词 laser-induced plasma theoretical imaging species distribution
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Numerical simulation of laser-induced plasma in background gas considering multiple interaction processes
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作者 Junxiao WANG Lei ZHANG +11 位作者 Shuqing WANG Maogen SU Duixiong SUN Jianghua HAN Guofu XIA Chenzhong DONG Qi MIN Weiguang MA Lei DONG wangbao yin Liantuan XIAO Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第3期1-10,共10页
Laser-induced plasma is often produced in the presence of background gas,which causes some new physical processes.In this work,a two-dimensional axisymmetric radiation fluid dynamics model is used to numerically simul... Laser-induced plasma is often produced in the presence of background gas,which causes some new physical processes.In this work,a two-dimensional axisymmetric radiation fluid dynamics model is used to numerically simulate the expansion process of plasma under different pressures and gases,in which the multiple interaction processes of diffusion,viscosity and heat conduction between the laser ablated target vapor and the background gas are further considered,and the spatio-temporal evolutions of plasma parameters(species number density,expansion velocity,size and electron temperature)as well as the emission spectra are obtained.The consistency between the actual and simulated spectra of aluminum plasma in 1 atm argon verifies the correctness of the model and the numerical simulation,thus providing a refinement analysis method for the basic research of plasma expansion in gases and the application of laser-induced breakdown spectroscopy. 展开更多
关键词 laser-induced plasma radiation fluid dynamics model DIFFUSION VISCOSITY heat conduction
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Theoretical simulation study of laser-induced plasma bombardment on bacteria
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作者 Junxiao WANG Yan ZHANG +6 位作者 Wanfei ZHANG Yong GUO Lei ZHANG Zefu YE Zhujun ZHU wangbao yin Suotang JIA 《Plasma Science and Technology》 SCIE EI CAS 2024年第10期101-107,共7页
With the rapid advancement of laser decontamination technology and growing awareness of microbial hazards,it becomes crucial to employ theoretical model to simulate and evaluate decontamination processes by laser-indu... With the rapid advancement of laser decontamination technology and growing awareness of microbial hazards,it becomes crucial to employ theoretical model to simulate and evaluate decontamination processes by laser-induced plasma.This study employs a two-dimensional axisymmetric fluid dynamics model to simulate the power density of plasma bombardment on bacteria and access its decontamination effects.The model considers the transport processes of vapor plasma and background gas molecules.Based on the destructive impact of high-speed moving particles in the plasma on bacteria,we investigate the bombardment power density under various conditions,including different laser spot sizes,wavelengths,plate's tilt angles,and plate-target spacing.The results reveal that the bombardment power density increases with a decrease in laser spot size and wavelength.For instance,when the plate is parallel to the target surface with a 1 mm spacing,the bombardment power density triples as the laser spot size decreases from 0.8 mm to 0.5 mm and quadruples as the wavelength decreases from 1064 nm to 266 nm.Notably,when the plate is parallel to the target with a relatively close spacing of 0.5 mm,the bombardment power density at 0°inclination increases sevenfold compared to 45°.This simulation study is essential for optimizing optical parameters and designing component layouts in decontamination devices using laser-induced plasma.The reduction of laser spot size,wavelength,plate-target spacing and aligning the plate parallel to the target,collectively contribute to achieving precise and effective decontamination. 展开更多
关键词 laser-induced breakdown spectroscopy fluid dynamics model bacterial decontamination
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