Pub Date : 2024-04-23DOI: 10.1088/1361-6595/ad4236
Raphaël Robert, Nader Sadeghi, Gerjan J M Hagelaar, L. Stafford, Françoise Massines
This work reports the results of an experimental and modelling study on dual-frequency Ar-NH3 dielectric barrier discharges (DBD) exhibiting the α – γ transition. A combination of space- and time-resolved optical absorption and emission spectroscopy is used to record spatio-temporal mappings of the Ar metastable number density, Ar 750.4 nm line emission intensity, and electron-Ar Bremsstrahlung continuum emission intensity. With the increase of the RF voltage amplitude in a 50 kHz-5 MHz DBD, maximum populations of Ar excited species (1s and 2p states, linked to the population of high-energy electrons) observed in the γ mode decrease and appear earlier in the low-frequency cycle. On the other hand, the density of the bulk electrons, monitored from the continuum emission intensity, increases, with a more prominent rise in the RF-α mode than in the γ regime. Such behaviors are consistent with the predictions of 1D fluid model and results from a decrease of the gas voltage required for self-maintenance of the cathode sheath in the γ breakdown.
{"title":"Influence of the RF voltage amplitude on the space- and time-resolved properties of RF-LF dielectric barrier discharges in α-γ mode","authors":"Raphaël Robert, Nader Sadeghi, Gerjan J M Hagelaar, L. Stafford, Françoise Massines","doi":"10.1088/1361-6595/ad4236","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4236","url":null,"abstract":"\u0000 This work reports the results of an experimental and modelling study on dual-frequency Ar-NH3 dielectric barrier discharges (DBD) exhibiting the α – γ transition. A combination of space- and time-resolved optical absorption and emission spectroscopy is used to record spatio-temporal mappings of the Ar metastable number density, Ar 750.4 nm line emission intensity, and electron-Ar Bremsstrahlung continuum emission intensity. With the increase of the RF voltage amplitude in a 50 kHz-5 MHz DBD, maximum populations of Ar excited species (1s and 2p states, linked to the population of high-energy electrons) observed in the γ mode decrease and appear earlier in the low-frequency cycle. On the other hand, the density of the bulk electrons, monitored from the continuum emission intensity, increases, with a more prominent rise in the RF-α mode than in the γ regime. Such behaviors are consistent with the predictions of 1D fluid model and results from a decrease of the gas voltage required for self-maintenance of the cathode sheath in the γ breakdown.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"24 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140665733","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 : 2024-04-18DOI: 10.1088/1361-6595/ad4054
Duarte Gonçalves, G. Bauville, P. Jeanney, M. Lino da Silva, Luis Alves, Stéphane Pasquiers, J. Santos Sousa
Atmospheric-pressure microplasma jets (μAPPJs) are versatile sources of reactive species with diverse applications. However, understanding the plasma chemistry in these jets is challenging due to plasma-flow interactions in heterogeneous gas mixtures. Spatial metastable density profiles help to understand these physical and chemical mechanisms. This work focuses on controlling the shielding gas around a μAPPJ. We use a dielectric barrier discharge co-axial reactor where a co-flow shields the pure argon jet with different N2-O2 gas mixtures. A voltage pulse (4 kV, 1 μs, 20 kHz) generates a first discharge at the pulse’s rising edge and a second discharge at the falling edge. Tunable diode laser absorption spectroscopy measures the local Ar(1s5) density. A pure N2 (100%N2-0%O2) co-flow leads to less reproducible and lower peak Ar(1s5) density (5.8 × 1013 cm−3). Increasing the O2 admixture in the co-flow yields narrower Ar(1s5) absorbance profiles and increases the Ar(1s5) density (6.9 × 1013 - 9.1 × 1013 cm−3). The position of the peak density is closer to the reactor for higher O2 fractions. Absence of N2 results in comparable Ar(1s5) densities between the first and second discharges (maxima of 9.1 × 1013 and 9.3 × 1013 cm−3, respectively). Local Ar(1s5) density profiles from pure N2 to pure O2 shielding provide insights into physical and chemical processes. The spatially-resolved data may contribute to optimising argon μAPPJ reactors across the various applications and to validate numerical models.
{"title":"Ar(1s5) density in a co-axial argon plasma jet with N2-O2 shielding","authors":"Duarte Gonçalves, G. Bauville, P. Jeanney, M. Lino da Silva, Luis Alves, Stéphane Pasquiers, J. Santos Sousa","doi":"10.1088/1361-6595/ad4054","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4054","url":null,"abstract":"\u0000 Atmospheric-pressure microplasma jets (μAPPJs) are versatile sources of reactive species with diverse applications. However, understanding the plasma chemistry in these jets is challenging due to plasma-flow interactions in heterogeneous gas mixtures. Spatial metastable density profiles help to understand these physical and chemical mechanisms. This work focuses on controlling the shielding gas around a μAPPJ. We use a dielectric barrier discharge co-axial reactor where a co-flow shields the pure argon jet with different N2-O2 gas mixtures. A voltage pulse (4 kV, 1 μs, 20 kHz) generates a first discharge at the pulse’s rising edge and a second discharge at the falling edge. Tunable diode laser absorption spectroscopy measures the local Ar(1s5) density. A pure N2 (100%N2-0%O2) co-flow leads to less reproducible and lower peak Ar(1s5) density (5.8 × 1013 cm−3). Increasing the O2 admixture in the co-flow yields narrower Ar(1s5) absorbance profiles and increases the Ar(1s5) density (6.9 × 1013 - 9.1 × 1013 cm−3). The position of the peak density is closer to the reactor for higher O2 fractions. Absence of N2 results in comparable Ar(1s5) densities between the first and second discharges (maxima of 9.1 × 1013 and 9.3 × 1013 cm−3, respectively). Local Ar(1s5) density profiles from pure N2 to pure O2 shielding provide insights into physical and chemical processes. The spatially-resolved data may contribute to optimising argon μAPPJ reactors across the various applications and to validate numerical models.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":" 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140689294","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 : 2024-04-18DOI: 10.1088/1361-6595/ad4055
P. Viegas, Jorge Silveira, T. C. Dias, O. Guaitella, A. Morillo-Candas, V. Guerra
Surface recombination in an oxygen DC glow discharge in a Pyrex (borosilicate glass) tube is studied via mesoscopic modelling and comparison with measurements of recombination probability. A total of 106 experimental conditions are assessed, with discharge current varying between 10 and 40 mA, pressure values ranging between 0.75 and 10 Torr, and fixed outer wall temperatures (Tw) of −20, 5, 25 and 50 ºC. The model includes O+O and O+O2 surface recombination reactions and a Tw dependent desorption frequency. The model is validated for all the 106 studied conditions and intends to have predictive capabilities. The analysis of the simulation results highlights that for Tw = −20 ºC and Tw = 5 ºC the dominant recombination mechanisms involve physisorbed oxygen atoms (OF) in Langmuir-Hinshelwood (L-H) recombination OF + OF and in Eley-Rideal (E-R) recombination O2 + OF, while for Tw = 25 ºC and Tw = 50 ºC processes involving chemisorbed oxygen atoms (OS) in E-R O + OS and L-H OF + OS also play a relevant role. A discussion is taken on the relevant recombination mechanisms and on ozone wall production, with relevance for higher pressure regimes.
通过介观建模以及与重组概率测量结果的比较，研究了派莱克斯（硼硅玻璃）管中氧气直流辉光放电的表面重组。共评估了 106 种实验条件，放电电流在 10 至 40 mA 之间变化，压力值在 0.75 至 10 托之间变化，外壁温度 (Tw) 固定为 -20、5、25 和 50 ºC。该模型包括 O+O 和 O+O2 表面重组反应以及与 Tw 有关的解吸频率。该模型针对所有 106 种研究条件进行了验证，并具有预测能力。对模拟结果的分析突出表明，在 Tw = -20 ºC 和 Tw = 5 ºC 条件下，主要的重组机制涉及物理吸附氧原子（OF）的朗缪尔-欣舍伍德（L-H）重组 OF + OF 和埃利-里达尔（E-R）重组 O2 + OF，而在 Tw = 25 ºC 和 Tw = 50 ºC 条件下，涉及化学吸附氧原子（OS）的 E-R O + OS 和 L-H OF + OS 过程也发挥了相关作用。本文讨论了相关的重组机制和臭氧壁的产生，以及与较高压力条件的相关性。
{"title":"Surface recombination in Pyrex in oxygen DC glow discharges: mesoscopic modelling and comparison with experiments","authors":"P. Viegas, Jorge Silveira, T. C. Dias, O. Guaitella, A. Morillo-Candas, V. Guerra","doi":"10.1088/1361-6595/ad4055","DOIUrl":"https://doi.org/10.1088/1361-6595/ad4055","url":null,"abstract":"\u0000 Surface recombination in an oxygen DC glow discharge in a Pyrex (borosilicate glass) tube is studied via mesoscopic modelling and comparison with measurements of recombination probability. A total of 106 experimental conditions are assessed, with discharge current varying between 10 and 40 mA, pressure values ranging between 0.75 and 10 Torr, and fixed outer wall temperatures (Tw) of −20, 5, 25 and 50 ºC. The model includes O+O and O+O2 surface recombination reactions and a Tw dependent desorption frequency. The model is validated for all the 106 studied conditions and intends to have predictive capabilities. The analysis of the simulation results highlights that for Tw = −20 ºC and Tw = 5 ºC the dominant recombination mechanisms involve physisorbed oxygen atoms (OF) in Langmuir-Hinshelwood (L-H) recombination OF + OF and in Eley-Rideal (E-R) recombination O2 + OF, while for Tw = 25 ºC and Tw = 50 ºC processes involving chemisorbed oxygen atoms (OS) in E-R O + OS and L-H OF + OS also play a relevant role. A discussion is taken on the relevant recombination mechanisms and on ozone wall production, with relevance for higher pressure regimes.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"164 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140686250","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 : 2024-04-16DOI: 10.1088/1361-6595/ad3f49
M. Benilov
When a hot arc spot has just formed on the cathode surface, e.g., in the course of arc ignition on a cold cathode, a significant part of the current still flows in the glow-discharge mode to the cold surface outside the spot. The near-cathode voltage continues to be high at all points of the cathode surface. The mean free path for collisions between the atoms and the ions within the plasma ball near the spot is comparable to, or exceeds, the thickness of the ionization layer, which is a part of the near-cathode non-equilibrium layer where the ion current to the cathode is generated. The evaluation of the ion current to the cathode surface under such conditions is revisited. A fluid description of the ion motion in the ionization layer is combined with a kinetic description of the atom motion. The resulting problem admits a simple analytical solution. Formulas for the evaluation of the ion current to the cathode for a wide range of conditions are derived and the possibilities of using these formulas to improve the accuracy of existing methods for modeling high-pressure arc discharges in relation to glow-to-arc transitions are discussed.
{"title":"Ionization layer with collision-free atoms at the edge of partially to fully ionized plasmas","authors":"M. Benilov","doi":"10.1088/1361-6595/ad3f49","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3f49","url":null,"abstract":"\u0000 When a hot arc spot has just formed on the cathode surface, e.g., in the course of arc ignition on a cold cathode, a significant part of the current still flows in the glow-discharge mode to the cold surface outside the spot. The near-cathode voltage continues to be high at all points of the cathode surface. The mean free path for collisions between the atoms and the ions within the plasma ball near the spot is comparable to, or exceeds, the thickness of the ionization layer, which is a part of the near-cathode non-equilibrium layer where the ion current to the cathode is generated. The evaluation of the ion current to the cathode surface under such conditions is revisited. A fluid description of the ion motion in the ionization layer is combined with a kinetic description of the atom motion. The resulting problem admits a simple analytical solution. Formulas for the evaluation of the ion current to the cathode for a wide range of conditions are derived and the possibilities of using these formulas to improve the accuracy of existing methods for modeling high-pressure arc discharges in relation to glow-to-arc transitions are discussed.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"6 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140697635","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 : 2024-04-16DOI: 10.1088/1361-6595/ad3f4a
Matthias Castor Karel Albrechts, Ivan Tsonev, A. Bogaerts
We have developed a comprehensive kinetic model to study the O atom kinetics in an O2 plasma and its afterglow. By adopting a pseudo-1D plug-flow formalism within the kinetic model, our aim is to assess how far the O atoms travel in the plasma afterglow, evaluating its potential as a source of O atoms for post-plasma gas conversion applications. Since we could not find experimental data for pure O2 plasma at atmospheric pressure, we first validated our model at low pressure (1-10 Torr) where very good experimental data are available. Good agreement between our model and experiments was achieved for the reduced electric field, gas temperature and the densities of the dominant neutral species, i.e. O2(a), O2(b) and O. Subsequently, we confirmed that the chemistry set is consistent with thermodynamic equilibrium calculations at atmospheric pressure. Finally, we investigated the O atom densities in the O2 plasma and its afterglow, for which we considered a microwave O2 plasma torch, operating at a pressure between 0.1 and 1 atm, for a flow rate of 20 slm and an SEI of 1656 kJ/mol. Our results show that for both pressure conditions, a high dissociation degree of ca. 92 % is reached within the discharge. However, the O atoms travel much further in the plasma afterglow for p = 0.1 atm (9.7 cm) than for p = 1 atm (1.4 cm), attributed to the longer lifetime (3.8 ms at 0.1 atm vs 1.8 ms at 1 atm) resulting from slower three-body recombination kinetics, as well as a higher volumetric flow rate.
我们建立了一个综合动力学模型来研究 O2 等离子体及其余辉中的 O 原子动力学。通过在动力学模型中采用伪一维塞流形式主义，我们的目的是评估 O 原子在等离子体余辉中的移动距离，从而评估其作为等离子体后气体转换应用的 O 原子源的潜力。由于我们无法找到大气压下纯 O2 等离子体的实验数据，因此我们首先在低压（1-10 托）下验证了我们的模型，因为在低压下可以获得非常好的实验数据。在降低电场、气体温度和主要中性物种（即 O2(a)、O2(b) 和 O 的密度方面，我们的模型与实验之间取得了良好的一致性。最后，我们研究了 O2 等离子体及其余辉中的 O 原子密度，为此我们考虑了微波 O2 等离子体炬，其工作压力介于 0.1 和 1 atm 之间，流速为 20 slm，SEI 为 1656 kJ/mol。我们的研究结果表明，在这两种压力条件下，放电过程中的解离度都高达约 92%。然而，在 p = 0.1 atm（9.7 厘米）时，O 原子在等离子体余辉中的移动距离比 p = 1 atm（1.4 厘米）时要远得多，这是因为三体重组动力学速度较慢以及容积流速较高，导致 O 原子的寿命较长（0.1 atm 时为 3.8 毫秒，1 atm 时为 1.8 毫秒）。
{"title":"Investigation of O atom kinetics in O2 plasma and its afterglow","authors":"Matthias Castor Karel Albrechts, Ivan Tsonev, A. Bogaerts","doi":"10.1088/1361-6595/ad3f4a","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3f4a","url":null,"abstract":"\u0000 We have developed a comprehensive kinetic model to study the O atom kinetics in an O2 plasma and its afterglow. By adopting a pseudo-1D plug-flow formalism within the kinetic model, our aim is to assess how far the O atoms travel in the plasma afterglow, evaluating its potential as a source of O atoms for post-plasma gas conversion applications. Since we could not find experimental data for pure O2 plasma at atmospheric pressure, we first validated our model at low pressure (1-10 Torr) where very good experimental data are available. Good agreement between our model and experiments was achieved for the reduced electric field, gas temperature and the densities of the dominant neutral species, i.e. O2(a), O2(b) and O. Subsequently, we confirmed that the chemistry set is consistent with thermodynamic equilibrium calculations at atmospheric pressure. Finally, we investigated the O atom densities in the O2 plasma and its afterglow, for which we considered a microwave O2 plasma torch, operating at a pressure between 0.1 and 1 atm, for a flow rate of 20 slm and an SEI of 1656 kJ/mol. Our results show that for both pressure conditions, a high dissociation degree of ca. 92 % is reached within the discharge. However, the O atoms travel much further in the plasma afterglow for p = 0.1 atm (9.7 cm) than for p = 1 atm (1.4 cm), attributed to the longer lifetime (3.8 ms at 0.1 atm vs 1.8 ms at 1 atm) resulting from slower three-body recombination kinetics, as well as a higher volumetric flow rate.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"10 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696065","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 : 2024-04-11DOI: 10.1088/1361-6595/ad3d82
Fang-Jie Zhou, D. Wen, Jian-Kai Liu, Ziqing Su, Kai Zhao, Yu-Ru Zhang, You-Nian Wang
It is known that in very-high-frequency capacitively coupled plasmas (VHF CCPs), the higher harmonics generated by nonlinear sheath motion can enhance the standing wave effect (SWE), which can lead to center-peaked plasma density profiles. In this work, an improved nonlinear electromagnetic model incorporating a transmission line model, an electron momentum balance model, a bulk plasma model, a collisionless nonlinear numerical sheath model, and an ion Monte-Carlo collision (MCC) model is developed to study the effects of low-frequency (LF) voltage VL on the nonlinear standing wave excitation, plasma uniformity, and ion energy and angular distribution functions (IEDFs and IADFs) in dual-frequency (DF) asymmetric capacitive argon discharges at relatively low pressure of 3 Pa. The plasma diffusion in the radial direction and ion dynamics within the LF oscillating sheath are self-consistently considered. The LF voltage VL at 2 MHz varies from 0 to 700 V while the high-frequency (HF) voltage VH at 60 MHz is fixed at 100 V. Simulation results indicate that without the addition of an LF source (i.e. VL = 0 V), there are a considerable number of high-order harmonics with short wavelengths, leading to significant SWE and central peak in the radial plasma density profile. Nevertheless, the high-order harmonic excitations tend to be weakened and merely occur around the phase of the full LF sheath collapse due to a shorter characteristic damping time of the surface waves as VL increases. This, combined with increased surface wavelengths of both the driving frequency and the higher harmonics at a higher VL, leads to suppressed standing waves and improved plasma uniformity. Meanwhile, the simulations show that both the low and the high energy peaks of IEDF move towards higher energies, and the energy peak separation width ΔE becomes wider with the increase of VL. The IEDF at the radial center of the powered electrode exhibits a broader ΔE than that at the edge. For the IADF, an increased VL results in more ions incident on the electrode with a smaller deflection angle. Because of a thinner sheath and a higher sheath voltage at the electrode center, the peak value of IADF at the electrode center is greater than that at the edge.
{"title":"Effects of low-frequency voltage on nonlinear standing wave excitation, plasma uniformity, and ion dynamics in dual-frequency asymmetric capacitive discharges","authors":"Fang-Jie Zhou, D. Wen, Jian-Kai Liu, Ziqing Su, Kai Zhao, Yu-Ru Zhang, You-Nian Wang","doi":"10.1088/1361-6595/ad3d82","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3d82","url":null,"abstract":"\u0000 It is known that in very-high-frequency capacitively coupled plasmas (VHF CCPs), the higher harmonics generated by nonlinear sheath motion can enhance the standing wave effect (SWE), which can lead to center-peaked plasma density profiles. In this work, an improved nonlinear electromagnetic model incorporating a transmission line model, an electron momentum balance model, a bulk plasma model, a collisionless nonlinear numerical sheath model, and an ion Monte-Carlo collision (MCC) model is developed to study the effects of low-frequency (LF) voltage VL on the nonlinear standing wave excitation, plasma uniformity, and ion energy and angular distribution functions (IEDFs and IADFs) in dual-frequency (DF) asymmetric capacitive argon discharges at relatively low pressure of 3 Pa. The plasma diffusion in the radial direction and ion dynamics within the LF oscillating sheath are self-consistently considered. The LF voltage VL at 2 MHz varies from 0 to 700 V while the high-frequency (HF) voltage VH at 60 MHz is fixed at 100 V. Simulation results indicate that without the addition of an LF source (i.e. VL = 0 V), there are a considerable number of high-order harmonics with short wavelengths, leading to significant SWE and central peak in the radial plasma density profile. Nevertheless, the high-order harmonic excitations tend to be weakened and merely occur around the phase of the full LF sheath collapse due to a shorter characteristic damping time of the surface waves as VL increases. This, combined with increased surface wavelengths of both the driving frequency and the higher harmonics at a higher VL, leads to suppressed standing waves and improved plasma uniformity. Meanwhile, the simulations show that both the low and the high energy peaks of IEDF move towards higher energies, and the energy peak separation width ΔE becomes wider with the increase of VL. The IEDF at the radial center of the powered electrode exhibits a broader ΔE than that at the edge. For the IADF, an increased VL results in more ions incident on the electrode with a smaller deflection angle. Because of a thinner sheath and a higher sheath voltage at the electrode center, the peak value of IADF at the electrode center is greater than that at the edge.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"22 7‐8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140715524","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 : 2024-04-11DOI: 10.1088/1361-6595/ad3d83
N. Škoro, K. Kutasi, Marija Puač, Z. L. Petrović, N. Puač
In this paper we present electrical characterization of a dielectric barrier discharge (DBD) plasma jet operating with He (2 slm and 3 slm) as working gas and interacting with Cu, PET and distilled H2O targets. We used a plasma jet with two copper electrodes wrapped around a glass tube. One electrode was powered by a high-voltage sinusoidal signal of 30 kHz, whereas the other electrode and the target holder were grounded. We have performed detailed investigation of the voltage and current waveforms, phase differences, volt-current (V-I) characteristics, calculated impedances and power deposition. The aim was to determine the influence of different target materials and their conductivity on the plasma properties. We calculated the total harmonic distortion (THD) factor that showed that the current through grounded electrode depends on the conductivity of the target. We also calculated the power delivered to the plasma core and the plasma plume regions and observed that the change in the target conductance influenced the power in both plasma regions. The experimentally characterized electrical circuit was simulated by a model of equivalent electrical circuit corresponding to the plasma-off and plasma-on regime. Voltage controlled current source was added as model of a streamer formed in plasma-on regime.
{"title":"Effect of target material on electrical properties of a two-electrode dielectric barrier helium plasma jet","authors":"N. Škoro, K. Kutasi, Marija Puač, Z. L. Petrović, N. Puač","doi":"10.1088/1361-6595/ad3d83","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3d83","url":null,"abstract":"\u0000 In this paper we present electrical characterization of a dielectric barrier discharge (DBD) plasma jet operating with He (2 slm and 3 slm) as working gas and interacting with Cu, PET and distilled H2O targets. We used a plasma jet with two copper electrodes wrapped around a glass tube. One electrode was powered by a high-voltage sinusoidal signal of 30 kHz, whereas the other electrode and the target holder were grounded. We have performed detailed investigation of the voltage and current waveforms, phase differences, volt-current (V-I) characteristics, calculated impedances and power deposition. The aim was to determine the influence of different target materials and their conductivity on the plasma properties. We calculated the total harmonic distortion (THD) factor that showed that the current through grounded electrode depends on the conductivity of the target. We also calculated the power delivered to the plasma core and the plasma plume regions and observed that the change in the target conductance influenced the power in both plasma regions. The experimentally characterized electrical circuit was simulated by a model of equivalent electrical circuit corresponding to the plasma-off and plasma-on regime. Voltage controlled current source was added as model of a streamer formed in plasma-on regime.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"15 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140712591","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 : 2024-04-09DOI: 10.1088/1361-6595/ad3c69
R. Masheyeva, M. Vass, Xiao-Kun Wang, Yong-Xin Liu, A. Derzsi, Peter Hartmann, J. Schulze, Zoltán Donkó
The electron power absorption mechanisms in electronegative capacitively coupled plasmas in CF4 are investigated using PIC/MCC simulations at a pressure of p=60 Pa, a driving frequency of f= 13.56 MHz for voltage amplitudes in the interval of Φ0=100...300 V, where pronounced self-organized density variations, i.e., striations, develop. The calculations are based on the Boltzmann Term Analysis, a computational diagnostic method capable of providing a complete spatio-temporal description of electron power absorption. The discharge undergoes an electron power absorption mode transition from the drift-ambipolar- to the striation-mode at Φ0=180 V. Although Ohmic power absorption is found to be the dominant electron power absorption mechanism in the parameter range considered, the electron power absorption mode transition can be inferred from the behaviour of the spatio-temporally averaged ambipolar power absorption as a function of the voltage amplitude. Furthermore, it is shown, that as a consequence of the presence of striations, the temporal modulation of the electron density leads to a temporal modulation of the ambipolar electric field, which is responsible for the striated structures of various physical quantities related to electrons, such as the electron temperature and the ionization source function.
{"title":"Electron power absorption in CF4 capacitively coupled RF plasmas operated in the striation mode","authors":"R. Masheyeva, M. Vass, Xiao-Kun Wang, Yong-Xin Liu, A. Derzsi, Peter Hartmann, J. Schulze, Zoltán Donkó","doi":"10.1088/1361-6595/ad3c69","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3c69","url":null,"abstract":"\u0000 The electron power absorption mechanisms in electronegative capacitively coupled plasmas in CF4 are investigated using PIC/MCC simulations at a pressure of p=60 Pa, a driving frequency of f= 13.56 MHz for voltage amplitudes in the interval of Φ0=100...300 V, where pronounced self-organized density variations, i.e., striations, develop. The calculations are based on the Boltzmann Term Analysis, a computational diagnostic method capable of providing a complete spatio-temporal description of electron power absorption. The discharge undergoes an electron power absorption mode transition from the drift-ambipolar- to the striation-mode at Φ0=180 V. Although Ohmic power absorption is found to be the dominant electron power absorption mechanism in the parameter range considered, the electron power absorption mode transition can be inferred from the behaviour of the spatio-temporally averaged ambipolar power absorption as a function of the voltage amplitude. Furthermore, it is shown, that as a consequence of the presence of striations, the temporal modulation of the electron density leads to a temporal modulation of the ambipolar electric field, which is responsible for the striated structures of various physical quantities related to electrons, such as the electron temperature and the ionization source function.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"56 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140727922","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 : 2024-04-09DOI: 10.1088/1361-6595/ad3c36
Arne Meindl, Ante Hecimovic, U. Fantz
A diagnostic setup for one-dimensionally spatially resolved TALIF detection of ground state oxygen atoms (2p4 3P2,1,0) is developed. The goal of this study is to investigate the evolution of temperatures and absolute number densities of oxygen atoms along the effluent of a low-pressure CO2 microwave discharge in order to gain insights into some of the mechanisms governing the post-discharge regime. The plasma source is operated at conditions of 600 W−1200 W of absorbed power with flow rates of 74 sccm and 370 sccm pure CO2 at pressures between 1.2 mbar and 5 mbar with specific energy inputs up to 111.9 eV/molecule. These operating conditions exhibit high CO2 conversions (up to 90 %) at low energy efficiencies (2−7.4 %), due to direct electron impact dissociation driving the conversion process resulting in splitting of CO2 into CO and metastable oxygen atoms. The TALIF measurements yield spatially resolved translational temperatures between 1000 K−1600 K for most operating conditions and axial positions along the effluent. Reference measurements with xenon 6p′ [3/2]2 are used for absolute number density calibration. The resulting axially resolved number density profiles of ground state atomic oxygen increase along the effluent, even at considerable distances of several centimeters from the active discharge, before they reach a maximum between 5×1020 m−3 and 2.2×1021 m−3 depending on the condition, and decrease after that. This behavior indicates the potential significance of quenching of metastable oxygen atoms within the post-discharge regime of the investigated CO2 discharges. The measured spatially resolved number density evolutions are qualitatively consistent with quenching via wall collisions being the dominant deactivation mechanism, underlining the importance of particle-wall interactions.
{"title":"Spatially resolved TALIF investigation of atomic oxygen in the effluent of a CO2 microwave discharge","authors":"Arne Meindl, Ante Hecimovic, U. Fantz","doi":"10.1088/1361-6595/ad3c36","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3c36","url":null,"abstract":"\u0000 A diagnostic setup for one-dimensionally spatially resolved TALIF detection of ground state oxygen atoms (2p4\u0000 3P2,1,0) is developed. The goal of this study is to investigate the evolution of temperatures and absolute number densities of oxygen atoms along the effluent of a low-pressure CO2 microwave discharge in order to gain insights into some of the mechanisms governing the post-discharge regime. The plasma source is operated at conditions of 600 W−1200 W of absorbed power with flow rates of 74 sccm and 370 sccm pure CO2 at pressures between 1.2 mbar and 5 mbar with specific energy inputs up to 111.9 eV/molecule. These operating conditions exhibit high CO2 conversions (up to 90 %) at low energy efficiencies (2−7.4 %), due to direct electron impact dissociation driving the conversion process resulting in splitting of CO2 into CO and metastable oxygen atoms. The TALIF measurements yield spatially resolved translational temperatures between 1000 K−1600 K for most operating conditions and axial positions along the effluent. Reference measurements with xenon 6p′ [3/2]2 are used for absolute number density calibration. The resulting axially resolved number density profiles of ground state atomic oxygen increase along the effluent, even at considerable distances of several centimeters from the active discharge, before they reach a maximum between 5×1020 m−3 and 2.2×1021 m−3 depending on the condition, and decrease after that. This behavior indicates the potential significance of quenching of metastable oxygen atoms within the post-discharge regime of the investigated CO2 discharges. The measured spatially resolved number density evolutions are qualitatively consistent with quenching via wall collisions being the dominant deactivation mechanism, underlining the importance of particle-wall interactions.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"97 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140723124","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 : 2024-04-09DOI: 10.1088/1361-6595/ad3c6a
Guoqiang Liu, Jiateng Zhou, Yang Xia, Y. X. Wang, Dongping Liu
Most surfaces treated by atmospheric pressure plasma jets (APPJs) in practical applications are notably three-dimensional. However, non-planar surfaces exhibit a diverse array of geometries, such as variations in curvature, roughness, and texture, complicating the prediction of surface ionization waves (SIW) propagation behavior across varied surface shapes, in the absence of sufficient experimental data. In this study, we made measurements of APPJ interactions with the non-planar substrates using the spatio-temporal resolved image method. Non-planar substrates encompassed wavy surfaces, arrayed hemispheres, and randomly textured raised surfaces. We tracked the morphology and velocity of SIW propagation over these surfaces. The results indicate that the SIW propagation on non-planar surfaces is significantly influenced by surface geometry and displays path selectivity, i.e., the SIW tends to propagate along valleys. The average propagation velocity of the SIW increases with the increasing radius of the wavy surface, as well as with the increased height of the arrayed hemispheres. This is attributable to the surface geometry constraining the dispersion of the SIW, causing it to concentrate and propagate in a singular direction. Moreover, the surface geometry markedly affects the distribution of the plasma treatment area, with the plasma inclined to enter valleys (where the light emission is significantly stronger than that of peaks) and to closely adhere to hemispherical surfaces. These patterns suggest a potential positive impact on treating skin surfaces such as pores, reducing bacteria in wrinkles, and addressing pimples.
{"title":"Interaction of atmospheric pressure helium plasma jet with non-planar substrates: path selectivity of surface ionization wave","authors":"Guoqiang Liu, Jiateng Zhou, Yang Xia, Y. X. Wang, Dongping Liu","doi":"10.1088/1361-6595/ad3c6a","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3c6a","url":null,"abstract":"\u0000 Most surfaces treated by atmospheric pressure plasma jets (APPJs) in practical applications are notably three-dimensional. However, non-planar surfaces exhibit a diverse array of geometries, such as variations in curvature, roughness, and texture, complicating the prediction of surface ionization waves (SIW) propagation behavior across varied surface shapes, in the absence of sufficient experimental data. In this study, we made measurements of APPJ interactions with the non-planar substrates using the spatio-temporal resolved image method. Non-planar substrates encompassed wavy surfaces, arrayed hemispheres, and randomly textured raised surfaces. We tracked the morphology and velocity of SIW propagation over these surfaces. The results indicate that the SIW propagation on non-planar surfaces is significantly influenced by surface geometry and displays path selectivity, i.e., the SIW tends to propagate along valleys. The average propagation velocity of the SIW increases with the increasing radius of the wavy surface, as well as with the increased height of the arrayed hemispheres. This is attributable to the surface geometry constraining the dispersion of the SIW, causing it to concentrate and propagate in a singular direction. Moreover, the surface geometry markedly affects the distribution of the plasma treatment area, with the plasma inclined to enter valleys (where the light emission is significantly stronger than that of peaks) and to closely adhere to hemispherical surfaces. These patterns suggest a potential positive impact on treating skin surfaces such as pores, reducing bacteria in wrinkles, and addressing pimples.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"17 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140723158","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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