The corona bar induced pre-ionization is a crucial preliminary process in the operation of ArF excimer lasers, directly impacting the uniformity and stability of output laser. However, the ultraviolet corona pre-ionization, as the mainstream method, is tightly coupled with the main discharge process, which complicates analysis. Here, we establish a numerical model of a single pulse discharge incorporating an external circuit to analyze the pre-ionization process and its influence on the breakdown characteristics. (1) By adopting detailed input parameters of photoionization model, we observe uniform and dispersed plasma propagation from the corona bar to the main gap. (2) An artificial boundary condition is proposed to investigate the phenomenological effect of high-energy electrons emission, emphasizing the influence of surface discharge along the cathode. (3) The differences between the two pre-ionization setup methods, photoionization and background electron density, are compared numerically. This study enhances the understanding of the pre-ionization process in ArF excimer lasers and provides theoretical insights for their optimization and design.
{"title":"Numerical investigation of discharge evolution and breakdown characteristics of ArF excimer lasers","authors":"Xiaochi Ma, Luying Bai, Yifei Zhu, Xinxian Jiang, Yun Wu","doi":"10.1088/1361-6595/ad5df6","DOIUrl":"https://doi.org/10.1088/1361-6595/ad5df6","url":null,"abstract":"\u0000 The corona bar induced pre-ionization is a crucial preliminary process in the operation of ArF excimer lasers, directly impacting the uniformity and stability of output laser. However, the ultraviolet corona pre-ionization, as the mainstream method, is tightly coupled with the main discharge process, which complicates analysis. Here, we establish a numerical model of a single pulse discharge incorporating an external circuit to analyze the pre-ionization process and its influence on the breakdown characteristics. (1) By adopting detailed input parameters of photoionization model, we observe uniform and dispersed plasma propagation from the corona bar to the main gap. (2) An artificial boundary condition is proposed to investigate the phenomenological effect of high-energy electrons emission, emphasizing the influence of surface discharge along the cathode. (3) The differences between the two pre-ionization setup methods, photoionization and background electron density, are compared numerically. This study enhances the understanding of the pre-ionization process in ArF excimer lasers and provides theoretical insights for their optimization and design.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"8 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141685969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vacuum arc discharge with metal-deuteride cathode can generate supersonic deuterium ion jet, which finds important applications in vacuum arc ions sources. In this study, a 1D3V spherical PIC-DSMC cathode spot model with titanium-deuteride cathode is developed to investigate the ionization and acceleration of deuterium ions from vacuum breakdown to steady-arc stage. The effects of cathode deuteration concentration on the deuterium ion fraction and kinetic energy are also analyzed. The results show that the released deuterium atoms start to be ionized at about tens of nanometers far away from cathode and then be fully-ionized at about 2 μm as cathode potential drop gradually building up. The proportion of deuterium ions in plasma is approximately same as the proportion of deuterium atoms in cathode material. Velocity separation of deuterium and titanium ions occurs due to the acceleration of electric field during the vacuum breakdown stage, however, the predominant ion-ion coulomb collisions wipe out this separation at the steady-arc stage. Shifting the deuterium atoms concentration in cathode under the constant arc burning voltage produces an approximately equal current density, and increases the velocities of all ion species. The higher ion kinetic energy is gained by reducing the ohmic heating dissipation, which is facilitated by the lower plasma resistivity under the increased deuterium ion density.
{"title":"Study on the properties of deuterium ions in composite cathode vacuum arc discharge","authors":"Mengmeng Song, Q. Sun, Wei Yang, Ye Dong, Han-tian Zhang, Ziming Wang, Zhaohui Liu, Qian-hong Zhou","doi":"10.1088/1361-6595/ad57ec","DOIUrl":"https://doi.org/10.1088/1361-6595/ad57ec","url":null,"abstract":"\u0000 Vacuum arc discharge with metal-deuteride cathode can generate supersonic deuterium ion jet, which finds important applications in vacuum arc ions sources. In this study, a 1D3V spherical PIC-DSMC cathode spot model with titanium-deuteride cathode is developed to investigate the ionization and acceleration of deuterium ions from vacuum breakdown to steady-arc stage. The effects of cathode deuteration concentration on the deuterium ion fraction and kinetic energy are also analyzed. The results show that the released deuterium atoms start to be ionized at about tens of nanometers far away from cathode and then be fully-ionized at about 2 μm as cathode potential drop gradually building up. The proportion of deuterium ions in plasma is approximately same as the proportion of deuterium atoms in cathode material. Velocity separation of deuterium and titanium ions occurs due to the acceleration of electric field during the vacuum breakdown stage, however, the predominant ion-ion coulomb collisions wipe out this separation at the steady-arc stage. Shifting the deuterium atoms concentration in cathode under the constant arc burning voltage produces an approximately equal current density, and increases the velocities of all ion species. The higher ion kinetic energy is gained by reducing the ohmic heating dissipation, which is facilitated by the lower plasma resistivity under the increased deuterium ion density.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"35 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141348483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1088/1361-6595/ad57ee
Minyeul Lee, Sungyoung Yoon, Meehyun Lim, Sungyeol Kim, Jonghwa Shin
Precise control of electromagnetic fields is critical in many advanced manufacturing processes, such as those used in the semiconductor industry, where device performance relies on precision and uniformity. Varying the relative permittivity of adjacent materials effectively controls electromagnetic fields in a three-dimensional space. However, finding suitable low dielectric-loss materials with a large tunability is challenging. To overcome this, metamaterial-based approaches have been explored. While promising, further research is required to enlarge the frequency bandwidth, widen the achievable permittivity ranges, and find a simple tuning mechanism. Here, we propose a solution based on a geometrically-designable permittivity enhancement principle, free from the fundamental constraints on the frequency bandwidth and dispersion inherent in resonance-based tuning principles. We report an experimentally measured record-high broadband permittivity change over 250 %. The proposed structure includes a patterned semiconductor material that allows tuning the effective permittivity through carrier-density modulation. This carrier-responsive metamaterial (CRM) exhibits frequency-independent behavior over several decades of frequencies and a large tunability in the permittivities based on the dynamically controlled conductivity of the semiconductor region. We present an intuitive model that can explain the relationship between the CRM’s structure and properties including its effective permittivity and loss tangent. We also provide rigorous numerical simulations and experimental measurements to verify the concept. As an application, we explore CRM’s potential in plasma control, revealing its ability to influence plasma uniformity by over 10%. This research illuminates CRM’s versatile functionality and potential impact across diverse technological domains.
{"title":"Tunable metamaterials with carrier-induced effective permittivity for active control of electromagnetic fields in semiconductor manufacturing device","authors":"Minyeul Lee, Sungyoung Yoon, Meehyun Lim, Sungyeol Kim, Jonghwa Shin","doi":"10.1088/1361-6595/ad57ee","DOIUrl":"https://doi.org/10.1088/1361-6595/ad57ee","url":null,"abstract":"\u0000 Precise control of electromagnetic fields is critical in many advanced manufacturing processes, such as those used in the semiconductor industry, where device performance relies on precision and uniformity. Varying the relative permittivity of adjacent materials effectively controls electromagnetic fields in a three-dimensional space. However, finding suitable low dielectric-loss materials with a large tunability is challenging. To overcome this, metamaterial-based approaches have been explored. While promising, further research is required to enlarge the frequency bandwidth, widen the achievable permittivity ranges, and find a simple tuning mechanism. Here, we propose a solution based on a geometrically-designable permittivity enhancement principle, free from the fundamental constraints on the frequency bandwidth and dispersion inherent in resonance-based tuning principles. We report an experimentally measured record-high broadband permittivity change over 250 %. The proposed structure includes a patterned semiconductor material that allows tuning the effective permittivity through carrier-density modulation. This carrier-responsive metamaterial (CRM) exhibits frequency-independent behavior over several decades of frequencies and a large tunability in the permittivities based on the dynamically controlled conductivity of the semiconductor region. We present an intuitive model that can explain the relationship between the CRM’s structure and properties including its effective permittivity and loss tangent. We also provide rigorous numerical simulations and experimental measurements to verify the concept. As an application, we explore CRM’s potential in plasma control, revealing its ability to influence plasma uniformity by over 10%. This research illuminates CRM’s versatile functionality and potential impact across diverse technological domains.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"47 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141347199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1088/1361-6595/ad57ed
D. Lopaev, Y. Mankelevich, A. Kropotkin, D. Voloshin, T. V. Rakhimova
H- ion dynamics in the positive column of H2 dc glow discharge was studied by the laser photodetachment technique in a wide range of pressure, 0.1–3 Torr, and current, 1-30 mA which cover a range of E/N from ~ 40 Td up to ~ 170 Td. Using partial modulation of discharge current it is shown that the H– concentration follows H atom dynamics due to fast detachment reaction with the atoms: the higher H density, the lower H-/ne ratio. Dynamics of H atom density at discharge modulation was measured by the time-resolved actinometry on Ar atoms while H2vibrational temperature was estimated by comparing measured and simulated H2 VUV absorption spectra. The analysis of the experimental dependencies of H– and H/H2 on the discharge parameters allowed estimating the effective rate constant of H– production in the discharge as a function of the reduced electric field. For this the discharge model including self-consistently state-to-state vibrational kinetics as well as H2 highly excited electronic states was developed. The main processes, that contribute to H– production and loss, are discussed in detail. Dissociative attachment to vibrationally excited H2(v) molecules is the main channel of H- production but occurs via the excitation of the well-known low-energy (εth ≈ 3 eV) shape resonance of H2-(X2Σu+) only at low E/N. At high E/N, the H- production mostly occurs via the excitation of the high-energy H2- states, such as H2-(B2Σg+, A2Σg+, C2Πu) and Feshbach resonances similar to H2-(2Σg+) Rydberg state.
{"title":"H– production in hydrogen DC glow discharge.","authors":"D. Lopaev, Y. Mankelevich, A. Kropotkin, D. Voloshin, T. V. Rakhimova","doi":"10.1088/1361-6595/ad57ed","DOIUrl":"https://doi.org/10.1088/1361-6595/ad57ed","url":null,"abstract":"\u0000 H- ion dynamics in the positive column of H2 dc glow discharge was studied by the laser photodetachment technique in a wide range of pressure, 0.1–3 Torr, and current, 1-30 mA which cover a range of E/N from ~ 40 Td up to ~ 170 Td. Using partial modulation of discharge current it is shown that the H– concentration follows H atom dynamics due to fast detachment reaction with the atoms: the higher H density, the lower H-/ne ratio. Dynamics of H atom density at discharge modulation was measured by the time-resolved actinometry on Ar atoms while H2vibrational temperature was estimated by comparing measured and simulated H2 VUV absorption spectra. The analysis of the experimental dependencies of H– and H/H2 on the discharge parameters allowed estimating the effective rate constant of H– production in the discharge as a function of the reduced electric field. For this the discharge model including self-consistently state-to-state vibrational kinetics as well as H2 highly excited electronic states was developed. The main processes, that contribute to H– production and loss, are discussed in detail. Dissociative attachment to vibrationally excited H2(v) molecules is the main channel of H- production but occurs via the excitation of the well-known low-energy (εth ≈ 3 eV) shape resonance of H2-(X2Σu+) only at low E/N. At high E/N, the H- production mostly occurs via the excitation of the high-energy H2- states, such as H2-(B2Σg+, A2Σg+, C2Πu) and Feshbach resonances similar to H2-(2Σg+) Rydberg state.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"46 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141349720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1088/1361-6595/ad546b
J. Hnilica, M. Šlapanská, M. Kroker, P. Klein, Petr Vasina
Investigating spokes in high-power impulse magnetron sputtering discharge requires non-invasive diagnostic methods to characterise accurately spoke properties. A fast photodiode and a cylindrical Langmuir probe were employed to synchronise the moment of acquisition of the optical emission spectrum with the position of a passing spoke. This study provides statistical data analysis to bring insights into spoke characteristics in a non-reactive argon atmosphere, employing aluminium, chromium, copper, titanium, and tungsten targets. Utilising different target materials, the objective is to describe basic parameters such as shape, length, and propagation velocity of spokes and also analyse spoke inner parameters such as floating potential and spectral emission, under nearly identical experimental conditions. From the optical emission, the most prominent species within the spoke were determined. Additionally, the mechanism governing spoke movement was described using a phenomenological model.
{"title":"Spatially resolved optical emission analysis of spokes in HiPIMS utilising Al, Cr, Cu, Ti, and W targets","authors":"J. Hnilica, M. Šlapanská, M. Kroker, P. Klein, Petr Vasina","doi":"10.1088/1361-6595/ad546b","DOIUrl":"https://doi.org/10.1088/1361-6595/ad546b","url":null,"abstract":"Investigating spokes in high-power impulse magnetron sputtering discharge requires non-invasive diagnostic methods to characterise accurately spoke properties. A fast photodiode and a cylindrical Langmuir probe were employed to synchronise the moment of acquisition of the optical emission spectrum with the position of a passing spoke. This study provides statistical data analysis to bring insights into spoke characteristics in a non-reactive argon atmosphere, employing aluminium, chromium, copper, titanium, and tungsten targets. Utilising different target materials, the objective is to describe basic parameters such as shape, length, and propagation velocity of spokes and also analyse spoke inner parameters such as floating potential and spectral emission, under nearly identical experimental conditions. From the optical emission, the most prominent species within the spoke were determined. Additionally, the mechanism governing spoke movement was described using a phenomenological model.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"50 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.1088/1361-6595/ad5400
Takuma Uemura, Hiroyuki Nishida, Ryo Ono, A. Komuro
Studies on the dielectric surface parameters and dielectric barrier discharges (DBD) characteristics considering the influence of gases in DBD on the surface charge distribution are scarce. Thus, to overcome this research gap, this study measured the potential distributions of AC-driven surface dielectric barrier discharges (SDBD) in oxygen (O2), synthetic air, and nitrogen (N2) as background gases using the Pockels effect. The results showed that the patterns of the filamentary discharges generated during the positive voltage polarity phase differed depending on the O2 ratio. In addition, the electrostatic repulsion forces between the residual charge and the newly created filament were analysed from the measured potential distribution, and the greatest effect was observed in air, rather than in N2 and O2. The potential distribution was transformed into a charge density distribution and compared with the discharge luminescence in air and N2. The results showed that the shape of the filament tip differed between the charge density and discharge luminescence only in the case of air, which was attributed to the effect of attachment reactions on the formation of residual charge. The measurements showed that in a surface discharge, similar to the case in a volume discharge, the photoionisation and ionisation coefficients significantly affected the geometrical properties of the discharges.
{"title":"Effect of nitrogen/oxygen ratios on surface charge distributions generated by repetitive surface dielectric barrier discharges","authors":"Takuma Uemura, Hiroyuki Nishida, Ryo Ono, A. Komuro","doi":"10.1088/1361-6595/ad5400","DOIUrl":"https://doi.org/10.1088/1361-6595/ad5400","url":null,"abstract":"\u0000 Studies on the dielectric surface parameters and dielectric barrier discharges (DBD) characteristics considering the influence of gases in DBD on the surface charge distribution are scarce. Thus, to overcome this research gap, this study measured the potential distributions of AC-driven surface dielectric barrier discharges (SDBD) in oxygen (O2), synthetic air, and nitrogen (N2) as background gases using the Pockels effect. The results showed that the patterns of the filamentary discharges generated during the positive voltage polarity phase differed depending on the O2 ratio. In addition, the electrostatic repulsion forces between the residual charge and the newly created filament were analysed from the measured potential distribution, and the greatest effect was observed in air, rather than in N2 and O2. The potential distribution was transformed into a charge density distribution and compared with the discharge luminescence in air and N2. The results showed that the shape of the filament tip differed between the charge density and discharge luminescence only in the case of air, which was attributed to the effect of attachment reactions on the formation of residual charge. The measurements showed that in a surface discharge, similar to the case in a volume discharge, the photoionisation and ionisation coefficients significantly affected the geometrical properties of the discharges.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"37 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141387571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-24DOI: 10.1088/1361-6595/ad5045
Minkeun Lee, Junbeom Park, Jiseong Nam, June Young Kim, Kyoung-Jae Chung
The generation of low-energy electrons is essential for the plasma source of the charge neutralizer system within the ion implanter process of semiconductors and displays, owing to their exceptional capability of being effectively transported along their ion beams. In this study, we propose a method to produce non-Maxwellian electron energy probability functions (eepfs) characterized by low-energy-abundant electrons, specifically below 5 eV, across an electron extraction system. In the electron transport region with an axial magnetic field under conditions of high discharge voltage and gas flow rate, we observed a significant increase in low-energy electrons in eepfs. The simple global model proposed to analyze these results demonstrated that the wall loss of electrons can be reduced by an elevated plasma potential, which is influenced by the ionization rate in the transport region. These results are consistent with the experimentally measured plasma potential and electron density. Additionally, the reduction in wall losses and increased ionization rate within the transport region resulted in the relaxation of the plasma potential gradient. This phenomenon effectively inhibited the cutting of low-energy electrons within the eepfs, thereby facilitating their consequential transport to the target. This study emphasizes the significance of increasing the ionization rate and minimizing the potential gradient for the dual purposes of generating low-energy electrons and directing them towards the target.
在半导体和显示器的离子注入器工艺中，低能电子的产生对于电荷中和系统的等离子体源至关重要，因为低能电子具有沿离子束有效传输的特殊能力。在这项研究中，我们提出了一种在电子萃取系统中产生非麦克斯韦电子能量概率函数（eepfs）的方法，其特点是低能量电子丰富，特别是低于 5 eV 的电子。在高放电电压和气体流速条件下的轴向磁场电子传输区域，我们观察到 eepfs 中的低能电子显著增加。为分析这些结果而提出的简单全局模型表明，电子的壁面损失可以通过提高等离子体电位来减少，而等离子体电位则受传输区电离率的影响。这些结果与实验测量的等离子体电位和电子密度一致。此外，传输区域内壁损耗的减少和电离率的增加导致了等离子体电位梯度的松弛。这一现象有效地抑制了低能电子在等离子体内的切割，从而促进了低能电子向目标的传输。这项研究强调了提高电离率和尽量减小电势梯度对产生低能电子并将其引向目标的双重目的的重要性。
{"title":"Generation of low-energy abundant electron energy probability functions using a magnetized plasma source","authors":"Minkeun Lee, Junbeom Park, Jiseong Nam, June Young Kim, Kyoung-Jae Chung","doi":"10.1088/1361-6595/ad5045","DOIUrl":"https://doi.org/10.1088/1361-6595/ad5045","url":null,"abstract":"\u0000 The generation of low-energy electrons is essential for the plasma source of the charge neutralizer system within the ion implanter process of semiconductors and displays, owing to their exceptional capability of being effectively transported along their ion beams. In this study, we propose a method to produce non-Maxwellian electron energy probability functions (eepfs) characterized by low-energy-abundant electrons, specifically below 5 eV, across an electron extraction system. In the electron transport region with an axial magnetic field under conditions of high discharge voltage and gas flow rate, we observed a significant increase in low-energy electrons in eepfs. The simple global model proposed to analyze these results demonstrated that the wall loss of electrons can be reduced by an elevated plasma potential, which is influenced by the ionization rate in the transport region. These results are consistent with the experimentally measured plasma potential and electron density. Additionally, the reduction in wall losses and increased ionization rate within the transport region resulted in the relaxation of the plasma potential gradient. This phenomenon effectively inhibited the cutting of low-energy electrons within the eepfs, thereby facilitating their consequential transport to the target. This study emphasizes the significance of increasing the ionization rate and minimizing the potential gradient for the dual purposes of generating low-energy electrons and directing them towards the target.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"10 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141098665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-20DOI: 10.1088/1361-6595/ad4ddc
Yuanyuan Xue, Ye Tian, Jiamin Li, M. Sui, Kezeng Pan, Shilei Zhong
Moving the laser focus to the vicinity of the gas-liquid interface is the key point for many new enhanced and new methods to improve the quality of spectral signals in water LIBS detection. Understanding the generation and evolution characteristics of the plasma induced by pulsed laser near the gas-liquid interface is of great significance for the establishment of evolution models and improvement of these new LIBS methods. In this paper, a set of slow horizontal flow auxiliary system is established to provide an ideal flat gas-liquid two-phase interface experimental condition. Experimental research on vertical incidence plane system was conducted using techniques such as time-resolved imaging, plasma characterization diagnosis, and spectral analysis. And the detection capabilities of the system were also tested. The characteristics and mechanisms of LIBS near the gas-liquid two-phase interface were investigated with the laser incident on the sample along the vertical direction. Simulation of the laser beam focusing process and observation of laser beam spot images show that the shift of plasma generation position relative to the focal point results from the refraction of the laser beam entering the solution from the air and the ‘interface effect’ of propagation on the vertical direction. Moreover, the plasma forms only the optical power density surpasses the breakdown threshold. In this work, plasma with smaller size, rounder shape, stronger radiation, higher temperature, and higher density can be produced when the focus position is in the liquid column 0.3 mm away from the upper interface. Simultaneously, for example, the Mg ion line at 285.213 nm, the obtained spectral intensity to signal-to-background ratio reaches the maximum value, and a better spectral signal can be obtained, which is 2-4 times of other positions, and the detection limits of the elements Na, Mg, and Ca also reach the lowest level, with 1.6-2.4 times of the detection limit of other focusing positions for Mg and 1.4-1.7 times for Ca, respectively.
{"title":"Characteristics of laser induced plasma near a flat gas-liquid interface and its effect on the performance of Laser induced breakdown spectroscopy (LIBS) detection.","authors":"Yuanyuan Xue, Ye Tian, Jiamin Li, M. Sui, Kezeng Pan, Shilei Zhong","doi":"10.1088/1361-6595/ad4ddc","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4ddc","url":null,"abstract":"\u0000 Moving the laser focus to the vicinity of the gas-liquid interface is the key point for many new enhanced and new methods to improve the quality of spectral signals in water LIBS detection. Understanding the generation and evolution characteristics of the plasma induced by pulsed laser near the gas-liquid interface is of great significance for the establishment of evolution models and improvement of these new LIBS methods. In this paper, a set of slow horizontal flow auxiliary system is established to provide an ideal flat gas-liquid two-phase interface experimental condition. Experimental research on vertical incidence plane system was conducted using techniques such as time-resolved imaging, plasma characterization diagnosis, and spectral analysis. And the detection capabilities of the system were also tested. The characteristics and mechanisms of LIBS near the gas-liquid two-phase interface were investigated with the laser incident on the sample along the vertical direction. Simulation of the laser beam focusing process and observation of laser beam spot images show that the shift of plasma generation position relative to the focal point results from the refraction of the laser beam entering the solution from the air and the ‘interface effect’ of propagation on the vertical direction. Moreover, the plasma forms only the optical power density surpasses the breakdown threshold. In this work, plasma with smaller size, rounder shape, stronger radiation, higher temperature, and higher density can be produced when the focus position is in the liquid column 0.3 mm away from the upper interface. Simultaneously, for example, the Mg ion line at 285.213 nm, the obtained spectral intensity to signal-to-background ratio reaches the maximum value, and a better spectral signal can be obtained, which is 2-4 times of other positions, and the detection limits of the elements Na, Mg, and Ca also reach the lowest level, with 1.6-2.4 times of the detection limit of other focusing positions for Mg and 1.4-1.7 times for Ca, respectively.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"17 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141119596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the study of electronegative CF4 capacitively coupled plasmas (CCP), plasma modulation is typically achieved by varying parameters such as pressure and voltage, et al. In this work, the particle-in-cell/Monte Carlo (PIC/MC) method is used to simulate modulation of CF4 CCP with injection of anions (F-) ion beam (FB). The results demonstrate that FB injection effectively enhances the dissociation collision process between F- ions and neutral molecules, thus altering the densities of electrons and ions. An effective modulation of the characteristic parameters of the plasma of CF4 can be achieved by controlling the current and energy of FB. Particularly noteworthy is the transition of the heating mode from the DA mode to the dissociation mode as the FB current increases to 0.038 A (energy fixed at 10 keV) or when the FB energy exceeds 10 keV (current fixed on 0.038 A). This transition is attributed to the generation of a substantial number of electrons through dissociative collisions. This approach provides insight into the controlled modulation of plasma characteristics in CF4 CCP, offering potential applications in various plasma-based technologies.
{"title":"Numerical characterization of capacitively coupled CF4 plasmas modulated by anion beam injection","authors":"Youyou Zhou, Jingwen Xu, Yu Wang, Hao Wu, Hongyu Wang, Wei Jiang, Ya Zhang","doi":"10.1088/1361-6595/ad4ddb","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4ddb","url":null,"abstract":"\u0000 In the study of electronegative CF4 capacitively coupled plasmas (CCP), plasma modulation is typically achieved by varying parameters such as pressure and voltage, et al. In this work, the particle-in-cell/Monte Carlo (PIC/MC) method is used to simulate modulation of CF4 CCP with injection of anions (F-) ion beam (FB). The results demonstrate that FB injection effectively enhances the dissociation collision process between F- ions and neutral molecules, thus altering the densities of electrons and ions. An effective modulation of the characteristic parameters of the plasma of CF4 can be achieved by controlling the current and energy of FB. Particularly noteworthy is the transition of the heating mode from the DA mode to the dissociation mode as the FB current increases to 0.038 A (energy fixed at 10 keV) or when the FB energy exceeds 10 keV (current fixed on 0.038 A). This transition is attributed to the generation of a substantial number of electrons through dissociative collisions. This approach provides insight into the controlled modulation of plasma characteristics in CF4 CCP, offering potential applications in various plasma-based technologies.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"27 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141120934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work numerically studies densities and mechanisms of OH species generated in atmospheric-pressure air dielectric barrier discharges with the model validated by experiments. The power consumption is measured, and the number of microdischarges (MDs) generated within a half period is captured by an intensified CCD camera. The OH densities of cases with various H2O concentrations are measured using ultraviolet absorption spectroscopy. The numerical model integrating the 1.5D discharge fluid model and 3D background gas model (BGM) is adopted to predict the MD behavior and the generation of species related to OH generation. The simulated OH densities cover the range of 1.1×10^19 and 1.6×10^19 m-3 in the cases studied, agreeing with those measured. The simulated results show that most OH radicals are generated in MDs, while the reactive section contributes around 2% of the total OH generation. The detailed analysis shows that atomic oxygen (O(1D) and O) and O3 contribute most of the OH generation in the MDs. In contrast, the self-association reactions (i.e., 2OH + M → H2O2 + M and 2OH → O + H2O) and NOx species consume more than 64% of OH radicals generated in MDs. In the BGM, it is interesting to find that reactive species NOx play significant roles in both the OH generation and depletion in the reactive section. The distributions of species related to the OH species obtained by the BGM are presented to elucidate the detailed chemistry of OH species in the reactive section.
{"title":"Characterization of OH species in kHz air/H2O atmospheric pressure dielectric barrier discharges","authors":"Cheng-Liang Huang, Tzu-Yi Liao, Yi-Ting He, Guan-Jung Lin, Wei-Hong Lai, Yi-Chi Chen, Kun-Mo Lin","doi":"10.1088/1361-6595/ad4ddd","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4ddd","url":null,"abstract":"\u0000 This work numerically studies densities and mechanisms of OH species generated in atmospheric-pressure air dielectric barrier discharges with the model validated by experiments. The power consumption is measured, and the number of microdischarges (MDs) generated within a half period is captured by an intensified CCD camera. The OH densities of cases with various H2O concentrations are measured using ultraviolet absorption spectroscopy. The numerical model integrating the 1.5D discharge fluid model and 3D background gas model (BGM) is adopted to predict the MD behavior and the generation of species related to OH generation. The simulated OH densities cover the range of 1.1×10^19 and 1.6×10^19 m-3 in the cases studied, agreeing with those measured. The simulated results show that most OH radicals are generated in MDs, while the reactive section contributes around 2% of the total OH generation. The detailed analysis shows that atomic oxygen (O(1D) and O) and O3 contribute most of the OH generation in the MDs. In contrast, the self-association reactions (i.e., 2OH + M → H2O2 + M and 2OH → O + H2O) and NOx species consume more than 64% of OH radicals generated in MDs. In the BGM, it is interesting to find that reactive species NOx play significant roles in both the OH generation and depletion in the reactive section. The distributions of species related to the OH species obtained by the BGM are presented to elucidate the detailed chemistry of OH species in the reactive section.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"17 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141120903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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