Pub Date : 2024-01-22DOI: 10.1088/1361-6595/ad211a
W. Khan, Pavel Dvorak, N. Bolouki, M. Mrkvičková
The absolute concentration and spatial distribution of ground-state atomic nitrogen (N) in an atmospheric pressure plasma jet were measured using the two-photon absorption laser-induced fluorescence (TALIF). The jet was ignited by radio frequency (RF) voltage in argon (or argon with nitrogen admixture) flowing through a silica tube. The spatially resolved measurements of atomic nitrogen concentration were realized in the effluent of the jet. In a pure argon plasma, the N concentration was increased with the distance from the silica tube and reached the maximum value (8*1014 cm-3) at the distance of 15 mm, and then sharply decreased at the end of the plume. On the contrary, plasma ignited in Ar with nitrogen admixture, the maximum N concentration was located directly at the end of the silica tube, where plasma starts to blow out into the ambient air. The highest N concentrations for 0.5 % and 2 % of N2 in the feed gas were 3*1015 cm-3 and 8*1015 cm-3, respectively.
{"title":"Concentration measurements of atomic nitrogen in an atmospheric-pressure RF plasma jet using a picosecond TALIF.","authors":"W. Khan, Pavel Dvorak, N. Bolouki, M. Mrkvičková","doi":"10.1088/1361-6595/ad211a","DOIUrl":"https://doi.org/10.1088/1361-6595/ad211a","url":null,"abstract":"\u0000 The absolute concentration and spatial distribution of ground-state atomic nitrogen (N) in an atmospheric pressure plasma jet were measured using the two-photon absorption laser-induced fluorescence (TALIF). The jet was ignited by radio frequency (RF) voltage in argon (or argon with nitrogen admixture) flowing through a silica tube. The spatially resolved measurements of atomic nitrogen concentration were realized in the effluent of the jet. In a pure argon plasma, the N concentration was increased with the distance from the silica tube and reached the maximum value (8*1014 cm-3) at the distance of 15 mm, and then sharply decreased at the end of the plume. On the contrary, plasma ignited in Ar with nitrogen admixture, the maximum N concentration was located directly at the end of the silica tube, where plasma starts to blow out into the ambient air. The highest N concentrations for 0.5 % and 2 % of N2 in the feed gas were 3*1015 cm-3 and 8*1015 cm-3, respectively.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"12 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139607410","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 : 2024-01-22DOI: 10.1088/1361-6595/ad2119
Liyang Zhang, Zhigang Liu, Yuntao Guo, Jinbao Liu, Kai Wang, Haiyun Luo, Yangyang Fu
This work proposes a coupled kinetic model to capture the spatiotemporal evolution behaviors of reactive species generated by a grating-like dielectric barrier discharge (DBD) operated in flowing humid air. The coupled model incorporates a zero-dimensional (0D) discharge model for the discharge filament and a 0D kinetic model or 2D fluid model for the afterglow region. The model is experimentally validated by the ozone measurements under different airflow rates and power levels. With the pseudo-1D plug flow approximation, the spatial distribution of species obtained by the 0D afterglow model agrees well with the 2D fluid model. The kinetics of reactive oxygen and nitrogen species (RONS) in the discharge and afterglow region and the underlying pathways are analyzed. It is predicted by the model that there exists an optimal discharge power or airflow rate to acquire a maximum density of short-lived species (OH, O2(a1Δ), HO2, etc.) delivered to a given location in the afterglow region. The key factor influencing the plasma chemistry is discharge power, regardless of initial species density, and less concerned with pulse width. The proposed model provides hints for a better understanding of DBD-relevant plasma chemistry operated in ambient air.
{"title":"Kinetic model of grating-like DBD fed with flowing humid air","authors":"Liyang Zhang, Zhigang Liu, Yuntao Guo, Jinbao Liu, Kai Wang, Haiyun Luo, Yangyang Fu","doi":"10.1088/1361-6595/ad2119","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2119","url":null,"abstract":"\u0000 This work proposes a coupled kinetic model to capture the spatiotemporal evolution behaviors of reactive species generated by a grating-like dielectric barrier discharge (DBD) operated in flowing humid air. The coupled model incorporates a zero-dimensional (0D) discharge model for the discharge filament and a 0D kinetic model or 2D fluid model for the afterglow region. The model is experimentally validated by the ozone measurements under different airflow rates and power levels. With the pseudo-1D plug flow approximation, the spatial distribution of species obtained by the 0D afterglow model agrees well with the 2D fluid model. The kinetics of reactive oxygen and nitrogen species (RONS) in the discharge and afterglow region and the underlying pathways are analyzed. It is predicted by the model that there exists an optimal discharge power or airflow rate to acquire a maximum density of short-lived species (OH, O2(a1Δ), HO2, etc.) delivered to a given location in the afterglow region. The key factor influencing the plasma chemistry is discharge power, regardless of initial species density, and less concerned with pulse width. The proposed model provides hints for a better understanding of DBD-relevant plasma chemistry operated in ambient air.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"77 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139606392","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 : 2024-01-22DOI: 10.1088/1361-6595/ad2117
S. Raskar, I. V. Adamovich, K. Konina, M. Kushner
The electric field distribution in the ionization waves propagating over a microchannel array dielectric surface, with the channels either empty or filled with distilled water, is measured by ps Electric Field Induced Second Harmonic (EFISH) generation. The surface ionization wave is initiated by the atmospheric pressure N2-Ar plasma jet impinging on the surface vertically and powered by ns pulse discharge bursts. The results show that the electric field inside the microchannels, specifically its horizontal component, is enhanced by up to a factor of 2. The field enhancement region is localized within the channels. The vertical electric field inside the channels lags in time compared to the field measured at the ridges, indicating the transient reversal of the ionization wave propagation direction across the channels (toward the jet). This is consistent with the phase-locked plasma emission images and confirmed by the kinetic modeling predictions, which show that the ionization wave “jumps” over the empty channels and propagates into the channels only after the jump between the adjacent ridges. When the channels are filled with water, the wave speed increases by up to 50%, due to the higher effective dielectric constant of the surface. No evidence of a significant electric field enhancement near the dielectric surface (ceramic or water) has been detected, within the spatial resolution of the present diagnostic, ~100 μm.
{"title":"Spatio-temporal electric field distributions in an atmospheric plasma jet impinging on a microchannel array surface","authors":"S. Raskar, I. V. Adamovich, K. Konina, M. Kushner","doi":"10.1088/1361-6595/ad2117","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2117","url":null,"abstract":"\u0000 The electric field distribution in the ionization waves propagating over a microchannel array dielectric surface, with the channels either empty or filled with distilled water, is measured by ps Electric Field Induced Second Harmonic (EFISH) generation. The surface ionization wave is initiated by the atmospheric pressure N2-Ar plasma jet impinging on the surface vertically and powered by ns pulse discharge bursts. The results show that the electric field inside the microchannels, specifically its horizontal component, is enhanced by up to a factor of 2. The field enhancement region is localized within the channels. The vertical electric field inside the channels lags in time compared to the field measured at the ridges, indicating the transient reversal of the ionization wave propagation direction across the channels (toward the jet). This is consistent with the phase-locked plasma emission images and confirmed by the kinetic modeling predictions, which show that the ionization wave “jumps” over the empty channels and propagates into the channels only after the jump between the adjacent ridges. When the channels are filled with water, the wave speed increases by up to 50%, due to the higher effective dielectric constant of the surface. No evidence of a significant electric field enhancement near the dielectric surface (ceramic or water) has been detected, within the spatial resolution of the present diagnostic, ~100 μm.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139608489","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 : 2024-01-22DOI: 10.1088/1361-6595/ad2118
Hao Du, Masahiro Sato, A. Komuro, Ryo Ono
O and OH radicals are the most important reactive oxygen species (ROS) in the plasma treatment of polymer surfaces. In our previous studies, we found that the modification efficiency of polypropylene (PP) surface by O radicals was approximately four times higher than that by OH radicals. This observation contrasts with the well-established fact that the chemical reactivity of O radicals with saturated hydrocarbons (CnH2(n+1)) is 50–60 times lower than that of OH radicals. In this study, molecular dynamics (MD) simulations with a reactive force field (ReaxFF) were used to explain this contradiction. The results showed that both O and OH radicals penetrated into the bulk of PP, namely physical adsorption occurred. The surface penetration depth of O radicals was greater than that of OH radicals. Compared to the case of OH radicals, alkoxy radicals (RO·) are more readily formed on the interactions of the PP surface with O radicals. Furthermore, the β-scission (splitting the C–C bonds) of alkoxy radicals can be accelerated by the physically adsorbed O radicals, leading to earlier breakage of PP chains. The improved efficacy of surface modification of PP upon exposure to O radicals, in contrast to OH radicals, can be attributed to the distinctions observed in the above three crucial processes.
在聚合物表面的等离子处理过程中，O 自由基和 OH 自由基是最重要的活性氧（ROS）。在之前的研究中，我们发现 O 自由基对聚丙烯（PP）表面的改性效率大约是 OH 自由基的四倍。这一观察结果与公认的事实形成鲜明对比，即 O 自由基与饱和碳氢化合物（CnH2(n+1)）的化学反应活性比 OH 自由基低 50-60 倍。本研究采用反应力场（ReaxFF）进行分子动力学（MD）模拟来解释这一矛盾。结果表明，O 自由基和 OH 自由基都渗透到了 PP 的主体中，即发生了物理吸附。O 自由基的表面渗透深度大于 OH 自由基。与 OH 自由基相比，烷氧基自由基 (RO-) 更容易在 PP 表面与 O 自由基相互作用时形成。此外，物理吸附的 O 自由基会加速烷氧基自由基的 β 分裂（分裂 C-C 键），从而导致聚丙烯链提前断裂。与羟自由基相比，暴露于 O 自由基时聚丙烯表面改性的效果更好，这可归因于在上述三个关键过程中观察到的区别。
{"title":"Theoretical mechanism behind the higher efficiency of O than OH radicals in polypropylene surface modification: A molecular dynamics study","authors":"Hao Du, Masahiro Sato, A. Komuro, Ryo Ono","doi":"10.1088/1361-6595/ad2118","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2118","url":null,"abstract":"\u0000 O and OH radicals are the most important reactive oxygen species (ROS) in the plasma treatment of polymer surfaces. In our previous studies, we found that the modification efficiency of polypropylene (PP) surface by O radicals was approximately four times higher than that by OH radicals. This observation contrasts with the well-established fact that the chemical reactivity of O radicals with saturated hydrocarbons (CnH2(n+1)) is 50–60 times lower than that of OH radicals. In this study, molecular dynamics (MD) simulations with a reactive force field (ReaxFF) were used to explain this contradiction. The results showed that both O and OH radicals penetrated into the bulk of PP, namely physical adsorption occurred. The surface penetration depth of O radicals was greater than that of OH radicals. Compared to the case of OH radicals, alkoxy radicals (RO·) are more readily formed on the interactions of the PP surface with O radicals. Furthermore, the β-scission (splitting the C–C bonds) of alkoxy radicals can be accelerated by the physically adsorbed O radicals, leading to earlier breakage of PP chains. The improved efficacy of surface modification of PP upon exposure to O radicals, in contrast to OH radicals, can be attributed to the distinctions observed in the above three crucial processes.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"21 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139609061","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}
Non-thermal plasma catalysis is a promising way to achieve high efficiency in applications such as energy conversion and chemical engineering. Although synergistic effect between plasma and catalysts has been preliminarily considered as an underlying mechanism of this type of catalysis, the formation of discharges in small-size catalyst pores, which is possible a crucial factor in plasma-activated catalysis, is still not well understood. In this paper, investigations on the interactions between a helium atmospheric pressure plasma jet (APPJ) and catalysts with micrometer-size pores of different shapes and sizes are conducted with a 2D fluid model. Simulation results show that the existence of pores makes subtle difference to the APPJ by changing equivalent capacitance, indicating the potential to achieve moderate and stable APPJ-catalysts interactions. Trace of air impurity in helium can promote the discharges in catalyst pores, and thus allow discharges forming in smaller pores. In the case when a catalyst channel is too small for direct APPJ penetration, we propose a method by producing a prior discharge in a relatively large cavity to supply seed electron to ignite discharges inside the channel. The effects of channel and cavity sizes are discussed from perspectives of discharge behavior and plasma-surface interactions. This work will contribute to the preparation of structured catalysts to potentially achieve higher efficient plasma catalysis, and better understanding the physical processes in plasma-surface interactions inside micrometer pores.
{"title":"Numerical investigation on the discharge formation in micrometer pores in structured catalyst irradiated by a helium atmospheric pressure plasma jet","authors":"Wenjun Ning, Hao Shang, Xueming Shen, Saikang Shen, Xiaolong Huang, Lihua Zhao, Shenli Jia","doi":"10.1088/1361-6595/ad208f","DOIUrl":"https://doi.org/10.1088/1361-6595/ad208f","url":null,"abstract":"\u0000 Non-thermal plasma catalysis is a promising way to achieve high efficiency in applications such as energy conversion and chemical engineering. Although synergistic effect between plasma and catalysts has been preliminarily considered as an underlying mechanism of this type of catalysis, the formation of discharges in small-size catalyst pores, which is possible a crucial factor in plasma-activated catalysis, is still not well understood. In this paper, investigations on the interactions between a helium atmospheric pressure plasma jet (APPJ) and catalysts with micrometer-size pores of different shapes and sizes are conducted with a 2D fluid model. Simulation results show that the existence of pores makes subtle difference to the APPJ by changing equivalent capacitance, indicating the potential to achieve moderate and stable APPJ-catalysts interactions. Trace of air impurity in helium can promote the discharges in catalyst pores, and thus allow discharges forming in smaller pores. In the case when a catalyst channel is too small for direct APPJ penetration, we propose a method by producing a prior discharge in a relatively large cavity to supply seed electron to ignite discharges inside the channel. The effects of channel and cavity sizes are discussed from perspectives of discharge behavior and plasma-surface interactions. This work will contribute to the preparation of structured catalysts to potentially achieve higher efficient plasma catalysis, and better understanding the physical processes in plasma-surface interactions inside micrometer pores.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"93 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139612703","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 : 2024-01-16DOI: 10.1088/1361-6595/ad1f38
K. Urabe, Minami Toyoda, Yoshinori Matsuoka, Koji Eriguchi
In high-pressure plasmas using gases diluted via a rare gas, small-fraction impurities in the discharge space significantly impact the basic plasma parameters and excited-species generation processes. This study investigated the behaviors of molecular impurities in a dielectric barrier discharge (DBD) generated in a flow of high-purity He gas using optical plasma diagnostics methods. The optical emission spectra obtained under various discharge conditions (pressure, flow rate, and voltage frequency) indicated the major impurity species in the He DBD as the H2O molecule, and the DBD decomposed the H2O before reaching the measurement spot. To quantitatively analyze the H2O fraction, time-resolved laser absorption spectroscopy (LAS) was performed to measure the lifetime of He metastable (Hem) atoms in the He-DBD. The H2O fraction in the He gas flow was derived from the dependence of Hem lifetime on the voltage frequency. In addition, a model was proposed to estimate the H2O fraction under various He pressure and flow rate conditions from few reference data. The procedures to perform the optical plasma diagnostics and evaluate the fraction and behaviors of H2O impurity are expected to facilitate a better understanding and control of high-pressure plasmas.
在使用稀有气体稀释的高压等离子体中，放电空间中的小部分杂质会对基本等离子体参数和激发态生成过程产生重大影响。本研究利用光学等离子体诊断方法研究了在高纯度 He 气体流中产生的介质势垒放电（DBD）中分子杂质的行为。在不同放电条件（压力、流速和电压频率）下获得的光学发射光谱表明，He DBD 中的主要杂质为 H2O 分子，DBD 在到达测量点之前就分解了 H2O。为了定量分析 H2O 部分，采用了时间分辨激光吸收光谱（LAS）来测量 He-DBD 中 He 可转移（Hem）原子的寿命。根据 Hem 的寿命与电压频率的关系，得出了 He 气体流中的 H2O 分量。此外，还提出了一个模型，用于根据少量参考数据估算不同 He 压力和流速条件下的 H2O 分数。进行光学等离子体诊断和评估 H2O 杂质的比例和行为的程序有望促进更好地理解和控制高压等离子体。
{"title":"Investigation of small-fraction molecular impurities in high-pressure helium plasmas using optical plasma diagnostic methods","authors":"K. Urabe, Minami Toyoda, Yoshinori Matsuoka, Koji Eriguchi","doi":"10.1088/1361-6595/ad1f38","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1f38","url":null,"abstract":"\u0000 In high-pressure plasmas using gases diluted via a rare gas, small-fraction impurities in the discharge space significantly impact the basic plasma parameters and excited-species generation processes. This study investigated the behaviors of molecular impurities in a dielectric barrier discharge (DBD) generated in a flow of high-purity He gas using optical plasma diagnostics methods. The optical emission spectra obtained under various discharge conditions (pressure, flow rate, and voltage frequency) indicated the major impurity species in the He DBD as the H2O molecule, and the DBD decomposed the H2O before reaching the measurement spot. To quantitatively analyze the H2O fraction, time-resolved laser absorption spectroscopy (LAS) was performed to measure the lifetime of He metastable (Hem) atoms in the He-DBD. The H2O fraction in the He gas flow was derived from the dependence of Hem lifetime on the voltage frequency. In addition, a model was proposed to estimate the H2O fraction under various He pressure and flow rate conditions from few reference data. The procedures to perform the optical plasma diagnostics and evaluate the fraction and behaviors of H2O impurity are expected to facilitate a better understanding and control of high-pressure plasmas.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":" 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139619764","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 : 2024-01-16DOI: 10.1088/1361-6595/ad1f37
M. Vass, David Schulenberg, Zoltán Donkó, I. Korolov, Peter Hartmann, J. Schulze, T. Mussenbrock
A spatially two dimensional fluid-MC hybrid (fluid-kinetic) simulation method is developed and applied to the COST reference microplasma jet operated in helium with an oxygen admixture of 0.5%, excited by a single frequency voltage waveform with $f=13.56$~MHz and $V_{rm rms}=275$~V. The simulation approach is based on a fluid model augmented by a Monte Carlo module that generates electron impact rates for the continuity equations solved by the fluid module. This method is capable of providing the same level of accuracy as PIC/MCC simulations with an agreement within 5-10% at atmospheric pressure, while being significantly faster (with a speedup factor of 30 for serial to 50 for parallel implementation). The simulation results are compared to previous measurements of atomic oxygen densities (Steuer D et {it al.} 2021 {it J. Phys. D: Appl. Phys.} {bf 54} 355204), and show a very good agreement. It is found that the buildup and saturation of the atomic oxygen density distribution along the jet are due to the interplay of chemical and electron impact reactions as well as of the gas flow. Comparing the simulation results to that of Liu Y et {it al.} 2021 {it J. Phys. D: Appl. Phys.} {bf 54} 275204, it is inferred that fluid models where a 2-term BE solver is used, fail to describe the COST jet in an accurate manner due to the underestimation of the electron impact rates.
我们开发了一种空间二维流体-MC混合（流体-动力学）模拟方法，并将其应用于COST参考微等离子体射流，该射流在氦气中运行，氧气掺量为0.5%，由单频电压波形激励，电压波形为$f=13.56$~MHz和$V_{rm rms}=275$~V。模拟方法以流体模型为基础，并辅以蒙特卡罗模块，为流体模块求解的连续性方程生成电子冲击率。这种方法能够提供与 PIC/MCC 模拟相同的精度水平，在大气压下的吻合度在 5-10% 以内，同时速度明显更快（串行实施的加速因子为 30，并行实施的加速因子为 50）。模拟结果与之前的原子氧密度测定结果进行了比较（Steuer D et {it al.} 2021 {it J. Phys. D: Appl. Phys.} {bf 54} 355204），结果显示两者吻合得非常好。研究发现，沿射流原子氧密度分布的积累和饱和是化学反应、电子撞击反应以及气体流动相互作用的结果。将模拟结果与 Liu Y et {it al.｝2021 {it J. Phys：Appl.｝{bf 54}275204，可以推断出使用2项BE求解器的流体模型由于低估了电子撞击速率而无法准确描述COST射流。
{"title":"A new 2D fluid-MC hybrid approach for simulating nonequilibrium atmospheric pressure plasmas: density distribution of atomic oxygen in radio-frequency plasma jets in He/O2 mixtures","authors":"M. Vass, David Schulenberg, Zoltán Donkó, I. Korolov, Peter Hartmann, J. Schulze, T. Mussenbrock","doi":"10.1088/1361-6595/ad1f37","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1f37","url":null,"abstract":"\u0000 A spatially two dimensional fluid-MC hybrid (fluid-kinetic) simulation method is developed and applied to the COST reference microplasma jet operated in helium with an oxygen admixture of 0.5%, excited by a single frequency voltage waveform with $f=13.56$~MHz and $V_{rm rms}=275$~V. The simulation approach is based on a fluid model augmented by a Monte Carlo module that generates electron impact rates for the continuity equations solved by the fluid module. This method is capable of providing the same level of accuracy as PIC/MCC simulations with an agreement within 5-10% at atmospheric pressure, while being significantly faster (with a speedup factor of 30 for serial to 50 for parallel implementation). The simulation results are compared to previous measurements of atomic oxygen densities (Steuer D et {it al.} 2021 {it J. Phys. D: Appl. Phys.} {bf 54} 355204), and show a very good agreement. It is found that the buildup and saturation of the atomic oxygen density distribution along the jet are due to the interplay of chemical and electron impact reactions as well as of the gas flow. Comparing the simulation results to that of Liu Y et {it al.} 2021 {it J. Phys. D: Appl. Phys.} {bf 54} 275204, it is inferred that fluid models where a 2-term BE solver is used, fail to describe the COST jet in an accurate manner due to the underestimation of the electron impact rates.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":" 31","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139619077","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 : 2024-01-15DOI: 10.1088/1361-6595/ad1ece
Gr Smith, Paola Diomede, A. Gibson, Scott J. Doyle, V. Guerra, M. Kushner, Timo Gans, J. Dedrick
Non-equilibrium inductively coupled plasmas (ICPs) operating in hydrogen are of significant interest for applications including large-area materials processing. The spatial distribution of the atomic hydrogen is of significant importance. Increasing control of spatial gas heating, which drives the formation of neutral species density gradients and the rate of gas-temperature-dependent reactions, is critical. In this study, we use 2D fluid-kinetic simulations with the Hybrid Plasma Equipment Model to investigate the spatially resolved production of atomic hydrogen in a low-pressure planar ICP operating in pure hydrogen (10 - 20 Pa or 0.075 - 0.15 Torr, 300 W). The reaction set incorporates self-consistent calculation of the spatially resolved gas temperature and 14 vibrationally excited states. We find that the formation of neutral-gas density gradients, which result from spatially non-uniform electrical power deposition at constant pressure, can drive significant variations in the vibrational distribution function and density of atomic hydrogen when gas heating is spatially resolved. This highlights the significance of spatial gas heating on the production of reactive species in relatively high-power-density plasma processing sources.
{"title":"Low-pressure inductively coupled plasmas in hydrogen: impact of gas heating on the spatial distribution of atomic hydrogen and vibrationally excited states","authors":"Gr Smith, Paola Diomede, A. Gibson, Scott J. Doyle, V. Guerra, M. Kushner, Timo Gans, J. Dedrick","doi":"10.1088/1361-6595/ad1ece","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1ece","url":null,"abstract":"\u0000 Non-equilibrium inductively coupled plasmas (ICPs) operating in hydrogen are of significant interest for applications including large-area materials processing. The spatial distribution of the atomic hydrogen is of significant importance. Increasing control of spatial gas heating, which drives the formation of neutral species density gradients and the rate of gas-temperature-dependent reactions, is critical. In this study, we use 2D fluid-kinetic simulations with the Hybrid Plasma Equipment Model to investigate the spatially resolved production of atomic hydrogen in a low-pressure planar ICP operating in pure hydrogen (10 - 20 Pa or 0.075 - 0.15 Torr, 300 W). The reaction set incorporates self-consistent calculation of the spatially resolved gas temperature and 14 vibrationally excited states. We find that the formation of neutral-gas density gradients, which result from spatially non-uniform electrical power deposition at constant pressure, can drive significant variations in the vibrational distribution function and density of atomic hydrogen when gas heating is spatially resolved. This highlights the significance of spatial gas heating on the production of reactive species in relatively high-power-density plasma processing sources.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":" 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139622671","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 : 2024-01-05DOI: 10.1088/1361-6595/ad1b6c
Congfu Ran, Xiongfeng Zhou, Zhiyong Wang, Kun Liu, K. Ostrikov
Despite the rapidly growing interest stemming from the broad-spectrum, high inactivation capacity, and environmental friendliness of the plasma-activated water (PAW), practical applications are limited because of the PAW’s short lifetime. While low-temperature storage can extend the lifetime, but the freezing and thawing processes are energy- and labor-intense and are generally not suitable for large-scale applications such as environmental and biomedical disinfection. This work addresses this issue by developing the ultra-long-life PAW at room temperature. The innovative approach is based on using DC needle-water discharges, wherein the gaseous products are blown out and absorbed separately by a gas flow. By simply adjusting the voltage and gas flow rates, two distinctive types of PAW with acidic hydrogen peroxide and nitrite as the main products are produced and separated in the discharge chamber and gas bubbling bottle. Intentional mixing of these two PAWs causes a chain chemical reaction dominated by peroxynitrite (ONOOH). This reaction can generate a variety of short-lived reactive species, thereby achieving the ultralong-lasting PAW with very stable inactivation ability. This study further demonstrates the ability to effectively control the reaction products in both chambers and provides insights into the secondary activation mechanism of short-lived reactive species stimulated by ONOOH.
{"title":"Ultralong-lasting plasma-activated water: production and control mechanisms","authors":"Congfu Ran, Xiongfeng Zhou, Zhiyong Wang, Kun Liu, K. Ostrikov","doi":"10.1088/1361-6595/ad1b6c","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1b6c","url":null,"abstract":"\u0000 Despite the rapidly growing interest stemming from the broad-spectrum, high inactivation capacity, and environmental friendliness of the plasma-activated water (PAW), practical applications are limited because of the PAW’s short lifetime. While low-temperature storage can extend the lifetime, but the freezing and thawing processes are energy- and labor-intense and are generally not suitable for large-scale applications such as environmental and biomedical disinfection. This work addresses this issue by developing the ultra-long-life PAW at room temperature. The innovative approach is based on using DC needle-water discharges, wherein the gaseous products are blown out and absorbed separately by a gas flow. By simply adjusting the voltage and gas flow rates, two distinctive types of PAW with acidic hydrogen peroxide and nitrite as the main products are produced and separated in the discharge chamber and gas bubbling bottle. Intentional mixing of these two PAWs causes a chain chemical reaction dominated by peroxynitrite (ONOOH). This reaction can generate a variety of short-lived reactive species, thereby achieving the ultralong-lasting PAW with very stable inactivation ability. This study further demonstrates the ability to effectively control the reaction products in both chambers and provides insights into the secondary activation mechanism of short-lived reactive species stimulated by ONOOH.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"25 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139383743","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 : 2024-01-05DOI: 10.1088/1361-6595/ad1b6d
Aymeric Bourlet, F. Tholin, Julien Labaune, F. Pechereau, A. Vincent‐Randonnier, Christophe O Laux
Direct current (DC) electric arcs are of particular interest because they can produce large volumes of thermal plasmas with controlled energy deposition. When such discharges are applied in a gas flow, convection displaces the top of the arc downstream while the arc roots remain attached to the electrodes, thus increasing the length of the arc over time. However, this growth is limited by a restrike phenomenon, which starts from streamers appearing in high electric field regions and shortcutting the long, stretched electric arc. From a numerical point of view, DC arcs can be efficiently simulated with a resistive magneto-hydrodynamics (MHD) model, with numerical requirements in terms of spatial and temporal discretization that are compatible with classic fluid dynamics and combustion simulations. However, arc restrikes rely on the propagation of streamer discharges that are highly non-neutral phenomena, whereas classical MHD assumes neutrality. To tackle this problem, we propose in this paper a model of restrike that can be used in an MHD approach. After describing the ideas of the model, we perform a parametric study of the input parameters to examine its influence on the discharge dynamics.
{"title":"Numerical model of restrikes in gliding arc discharges","authors":"Aymeric Bourlet, F. Tholin, Julien Labaune, F. Pechereau, A. Vincent‐Randonnier, Christophe O Laux","doi":"10.1088/1361-6595/ad1b6d","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1b6d","url":null,"abstract":"\u0000 Direct current (DC) electric arcs are of particular interest because they can produce large volumes of thermal plasmas with controlled energy deposition. When such discharges are applied in a gas flow, convection displaces the top of the arc downstream while the arc roots remain attached to the electrodes, thus increasing the length of the arc over time. However, this growth is limited by a restrike phenomenon, which starts from streamers appearing in high electric field regions and shortcutting the long, stretched electric arc. From a numerical point of view, DC arcs can be efficiently simulated with a resistive magneto-hydrodynamics (MHD) model, with numerical requirements in terms of spatial and temporal discretization that are compatible with classic fluid dynamics and combustion simulations. However, arc restrikes rely on the propagation of streamer discharges that are highly non-neutral phenomena, whereas classical MHD assumes neutrality. To tackle this problem, we propose in this paper a model of restrike that can be used in an MHD approach. After describing the ideas of the model, we perform a parametric study of the input parameters to examine its influence on the discharge dynamics.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"10 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139384085","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：