Pub Date : 2024-03-07DOI: 10.1088/2058-6272/ad3131
Liang Qin, Yao Li, Hao Guo, Nan Jiang, Ying Song, Rui Jia, Xiongfeng Zhou, Hao Yuan, Dezheng Yang
In this paper, self-designed multi-hollow needle electrodes are used as a high-voltage electrode in the packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large volume stable discharge. The dynamic characteristics of the plasma, the generated active species, and the energy transfer mechanisms in both positive discharge (PD) and negative discharge (ND) are investigated by using fast exposure ICCD images and time-resolved optical emission spectra. The experimental results show that the discharge intensity, number of discharge channels, and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multi-hollow needle electrode. During a single voltage pulse period, PD mainly develops in a streamer mode, which results in stronger discharge current, luminous intensity, and E/N compared to the diffuse mode observed in ND. In PD, as the gap between dielectric beads changes from 0 to 250 μm, the discharge between the gap of dielectric beads changes from the partial discharge to the standing filamentary micro-discharge, which makes the plasma not stay in the local area and is conducive to the propagation of surface streamer. In ND, the discharge only appears as a diffusion-like mode between the gap of dielectric beads, regardless of whether there is a discharge gap. Moreover, the generation of excited states N2 +(B2Σu +) and N2(C3Πu) is mainly observed in PD, which is attributed to the higher E/N in PD than that in ND. However, the generation of radical OH(A2Σ+) in ND is higher than that in PD. It is not directly dominated by E/N, but mainly by the resonant energy transfer process between metastable N2(A3Σu +) and OH(X2Π). Furthermore, both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration, and no vibration-to-rotation energy relaxation process is observed.
{"title":"Time-resolved characteristics of nanosecond pulsed multi-hollow needle plate packed bed dielectric barrier discharge","authors":"Liang Qin, Yao Li, Hao Guo, Nan Jiang, Ying Song, Rui Jia, Xiongfeng Zhou, Hao Yuan, Dezheng Yang","doi":"10.1088/2058-6272/ad3131","DOIUrl":"https://doi.org/10.1088/2058-6272/ad3131","url":null,"abstract":"\u0000 In this paper, self-designed multi-hollow needle electrodes are used as a high-voltage electrode in the packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large volume stable discharge. The dynamic characteristics of the plasma, the generated active species, and the energy transfer mechanisms in both positive discharge (PD) and negative discharge (ND) are investigated by using fast exposure ICCD images and time-resolved optical emission spectra. The experimental results show that the discharge intensity, number of discharge channels, and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multi-hollow needle electrode. During a single voltage pulse period, PD mainly develops in a streamer mode, which results in stronger discharge current, luminous intensity, and E/N compared to the diffuse mode observed in ND. In PD, as the gap between dielectric beads changes from 0 to 250 μm, the discharge between the gap of dielectric beads changes from the partial discharge to the standing filamentary micro-discharge, which makes the plasma not stay in the local area and is conducive to the propagation of surface streamer. In ND, the discharge only appears as a diffusion-like mode between the gap of dielectric beads, regardless of whether there is a discharge gap. Moreover, the generation of excited states N2\u0000 +(B2Σu\u0000 +) and N2(C3Πu) is mainly observed in PD, which is attributed to the higher E/N in PD than that in ND. However, the generation of radical OH(A2Σ+) in ND is higher than that in PD. It is not directly dominated by E/N, but mainly by the resonant energy transfer process between metastable N2(A3Σu\u0000 +) and OH(X2Π). Furthermore, both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration, and no vibration-to-rotation energy relaxation process is observed.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"15 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140259933","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}
The configuration of electrode voltage and zero magnetic point position has a significant impact on the performance of the double-stage Hall effect thruster. A 2D-3V model is established based on the two-magnetic peak type double-stage Hall thruster configuration, and a particle-in-cell simulation is carried out to investigate the influences of both acceleration electrode voltage value and zero magnetic point position on the thruster discharge characteristics and performances. The results indicate that increasing the acceleration voltage leads to a larger potential drop in the acceleration stage, allowing ions to gain higher energy, while electrons are easily absorbed by the intermediate electrode, resulting in a decrease in the anode current and ionization rate. When the acceleration voltage reaches 500 V, the thrust and efficiency are maximized, resulting in a 15% increase in efficiency. After the acceleration voltage exceeds 500 V, a potential barrier forms within the channel, leading to a decrease in thruster efficiency. Further study shows that as the second zero magnetic point moves towards the outlet of the channel, more electrons easily traverse the zero magnetic field region, participating in the ionization. The increase in the ionization rate leads to a gradual enhancement in both thrust and efficiency.
电极电压和零磁点位置的配置对双级霍尔效应推进器的性能有重要影响。基于双磁峰型双级霍尔推进器构型，建立了 2D-3V 模型，并进行了粒子入胞仿真，研究了加速电极电压值和零磁点位置对推进器放电特性和性能的影响。结果表明，增加加速电压会导致加速级电位下降，使离子获得更高的能量，而电子则容易被中间电极吸收，导致阳极电流和电离率下降。当加速电压达到 500 V 时，推力和效率达到最大化，从而使效率提高 15%。加速电压超过 500 V 后，通道内形成势垒，导致推进器效率下降。进一步的研究表明，当第二个零磁点向通道出口移动时，更多的电子容易穿越零磁场区域，参与电离。电离率的增加导致推力和效率逐渐提高。
{"title":"Influence of acceleration stage electrode voltage on the performance of double-stage Hall effect thruster with adjustable zero magnetic point","authors":"Long Chen, Weifu Gao, Zuojun Cui, Ping Duan, Xuesong Xu, Zichen Kan, Congqi Tan, Junyu Chen","doi":"10.1088/2058-6272/ad2fac","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2fac","url":null,"abstract":"\u0000 The configuration of electrode voltage and zero magnetic point position has a significant impact on the performance of the double-stage Hall effect thruster. A 2D-3V model is established based on the two-magnetic peak type double-stage Hall thruster configuration, and a particle-in-cell simulation is carried out to investigate the influences of both acceleration electrode voltage value and zero magnetic point position on the thruster discharge characteristics and performances. The results indicate that increasing the acceleration voltage leads to a larger potential drop in the acceleration stage, allowing ions to gain higher energy, while electrons are easily absorbed by the intermediate electrode, resulting in a decrease in the anode current and ionization rate. When the acceleration voltage reaches 500 V, the thrust and efficiency are maximized, resulting in a 15% increase in efficiency. After the acceleration voltage exceeds 500 V, a potential barrier forms within the channel, leading to a decrease in thruster efficiency. Further study shows that as the second zero magnetic point moves towards the outlet of the channel, more electrons easily traverse the zero magnetic field region, participating in the ionization. The increase in the ionization rate leads to a gradual enhancement in both thrust and efficiency.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"11 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140080988","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 : 2024-03-01DOI: 10.1088/2058-6272/ad2f3b
Yizhuohang Liu, P. Zheng, Xueyu Gong, Lan Yin, Xiaochang Chen, Yijun Zhong, Wenjun Yang
According to the physics of tokamak start-up, this paper constructs a zero-dimensional (0D) model applicable to electron cyclotron (EC) wave assisted start-up in NCST spherical torus (spherical tokamak) and CN-H1 stellarators. Using the constructed zero-dimensional model, the results obtained in this paper under the same conditions are compared and validated against references results for pure hydrogen plasma start-up in tokamak. The results are in good agreement, especially regarding electron temperature, ion temperature and plasma current. In the presence of finite Ohmic electric field in the spherical tokamak, a study on the EC wave assisted start-up of the NCST plasma at frequency of 28 GHz is conducted. The impact of the vertical magnetic field B v on EC wave assisted start-up, the relationship between EC wave injection power P inj, Ohmic electric field E, and initial hydrogen atom density nH0 is explored separately. It is found that under conditions of Ohmic electric field lower than ITER (~ 0.3 V m-1), EC wave can expand the operational space to achieve better plasma parameters. Simulating the process of 28 GHz EC wave start-up in the CN-H1 stellarator plasma, the plasma current in the zero-dimensional model is replaced with the current in the poloidal coil of the stellarator. Plasma start-up can be successfully achieved at injection powers in the hundreds of kilowatts range, resulting in electron densities on the order of 1017 to 1018 m-3.
根据托卡马克启动的物理学原理，本文构建了一个零维（0D）模型，适用于 NCST 球形环（球形托卡马克）和 CN-H1 恒星器的电子回旋波辅助启动。利用所构建的零维模型，本文将在相同条件下获得的结果与托卡马克中纯氢等离子体启动的参考结果进行了比较和验证。结果非常吻合，尤其是在电子温度、离子温度和等离子体电流方面。在球形托卡马克中存在有限欧姆电场的情况下，对频率为 28 GHz 的 NCST 等离子体的欧共体波辅助启动进行了研究。分别探讨了垂直磁场 B v 对电子波辅助启动的影响、电子波注入功率 P inj、欧姆电场 E 和初始氢原子密度 nH0 之间的关系。研究发现，在欧姆电场低于国际热核聚变实验堆（约 0.3 V m-1）的条件下，EC 波可以扩大运行空间，获得更好的等离子体参数。模拟在 CN-H1 恒星器等离子体中启动 28 GHz EC 波的过程时，零维模型中的等离子体电流被替换为恒星器极性线圈中的电流。等离子体启动可在数百千瓦的注入功率范围内成功实现，电子密度约为 1017 至 1018 m-3。
{"title":"Numerical study of plasmas start-up by electron cyclotron waves in NCST spherical tokamak and CN-H1 stellarator","authors":"Yizhuohang Liu, P. Zheng, Xueyu Gong, Lan Yin, Xiaochang Chen, Yijun Zhong, Wenjun Yang","doi":"10.1088/2058-6272/ad2f3b","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2f3b","url":null,"abstract":"\u0000 According to the physics of tokamak start-up, this paper constructs a zero-dimensional (0D) model applicable to electron cyclotron (EC) wave assisted start-up in NCST spherical torus (spherical tokamak) and CN-H1 stellarators. Using the constructed zero-dimensional model, the results obtained in this paper under the same conditions are compared and validated against references results for pure hydrogen plasma start-up in tokamak. The results are in good agreement, especially regarding electron temperature, ion temperature and plasma current. In the presence of finite Ohmic electric field in the spherical tokamak, a study on the EC wave assisted start-up of the NCST plasma at frequency of 28 GHz is conducted. The impact of the vertical magnetic field B\u0000 v on EC wave assisted start-up, the relationship between EC wave injection power P\u0000 inj, Ohmic electric field E, and initial hydrogen atom density nH0 is explored separately. It is found that under conditions of Ohmic electric field lower than ITER (~ 0.3 V m-1), EC wave can expand the operational space to achieve better plasma parameters. Simulating the process of 28 GHz EC wave start-up in the CN-H1 stellarator plasma, the plasma current in the zero-dimensional model is replaced with the current in the poloidal coil of the stellarator. Plasma start-up can be successfully achieved at injection powers in the hundreds of kilowatts range, resulting in electron densities on the order of 1017 to 1018 m-3.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":" 1172","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140091990","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 : 2024-02-26DOI: 10.1088/2058-6272/ad2d10
Xue Liu, Jiawei Zhang, Yi He, Jiamin Huang, Xiaoping Ma, Xiaoman Zhang, M. Lu, Yu Xin
Highly efficient and green ammonia production is an important demand for modern agriculture. In this paper, a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu2O electrocatalysis. In this method, NOx is provided by the gliding arc discharge and then electrolyzed by Cu/Cu2O after alkaline absorption. The electrical characteristics, the optical characteristics and the NOx production are investigated in discharges at different input voltage and the gas flow. The dependence of ammonia production through Cu/Cu2O electrocatalysis on pH value and reduction potential are determined by colorimetric method. In our study, two discharge modes are observed. At high input voltage and low gas flow, the discharge is operated with a stable plasma channel which is called the steady arc gliding discharge mode (A-G mode). As lowering input voltage and raising gas flow, the plasma channel is destroyed and high frequency breakdown occurs instead, which is known as the breakdown gliding discharge mode (B-G mode). The optimal NOx production of 7.34 mmol/h is obtained in the transition stage of the two discharge modes. The ammonia yield reaches 0.402 mmol/h/cm2 at pH value of 12.7 and reduction potential of -1.0 V vs RHE.
{"title":"Gliding arc discharge in combination with CuCu2O electrocatalysis for ammonia production","authors":"Xue Liu, Jiawei Zhang, Yi He, Jiamin Huang, Xiaoping Ma, Xiaoman Zhang, M. Lu, Yu Xin","doi":"10.1088/2058-6272/ad2d10","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2d10","url":null,"abstract":"\u0000 Highly efficient and green ammonia production is an important demand for modern agriculture. In this paper, a two-step ammonia production method is developed using a gliding arc discharge in combination with Cu/Cu2O electrocatalysis. In this method, NOx is provided by the gliding arc discharge and then electrolyzed by Cu/Cu2O after alkaline absorption. The electrical characteristics, the optical characteristics and the NOx production are investigated in discharges at different input voltage and the gas flow. The dependence of ammonia production through Cu/Cu2O electrocatalysis on pH value and reduction potential are determined by colorimetric method. In our study, two discharge modes are observed. At high input voltage and low gas flow, the discharge is operated with a stable plasma channel which is called the steady arc gliding discharge mode (A-G mode). As lowering input voltage and raising gas flow, the plasma channel is destroyed and high frequency breakdown occurs instead, which is known as the breakdown gliding discharge mode (B-G mode). The optimal NOx production of 7.34 mmol/h is obtained in the transition stage of the two discharge modes. The ammonia yield reaches 0.402 mmol/h/cm2 at pH value of 12.7 and reduction potential of -1.0 V vs RHE.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"21 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140430035","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}
The ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency (RF) plasma, is proposed for functionalization and immobilization on polyethersulfone (PES) supports to form supported ionic liquid membranes (SILMs) for CO2 separation. The effects of treatment time and transmembrane pressure difference on CO2 permeance were evaluated. The best gas permeation performance is obtained when the treatment time is 10 min, and the transmembrane pressure difference is 0.25 MPa. Characterization of the materials by FTIR, XPS and NMR demonstrates that ILs is grafted with carboxyl groups and deprotonated through plasma treatment. A preliminary mechanism for the plasma treatment and facilitated transport of CO2 has been proposed based on this basis.
{"title":"Enhancing CO2 transport with plasma-functionalized ionic liquid membranes","authors":"Ruchen Shu, Hui Xu, Chenxiao Pei, Nan Wang, Xingang Liu, Jianyuan Hou, Yuan Yuan, Renxi Zhang","doi":"10.1088/2058-6272/ad2d0f","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2d0f","url":null,"abstract":"\u0000 The ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency (RF) plasma, is proposed for functionalization and immobilization on polyethersulfone (PES) supports to form supported ionic liquid membranes (SILMs) for CO2 separation. The effects of treatment time and transmembrane pressure difference on CO2 permeance were evaluated. The best gas permeation performance is obtained when the treatment time is 10 min, and the transmembrane pressure difference is 0.25 MPa. Characterization of the materials by FTIR, XPS and NMR demonstrates that ILs is grafted with carboxyl groups and deprotonated through plasma treatment. A preliminary mechanism for the plasma treatment and facilitated transport of CO2 has been proposed based on this basis.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"48 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140429372","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 : 2024-02-26DOI: 10.1088/2058-6272/ad2d0e
Yuanbo Li, Xing Liu, T. Ye
A three-dimensional, two-temperature (2T) model of a lamellar cathode arc is constructed, drawing upon the conservation equations for mass, momentum, electron energy, and heavy particle energy, in addition to Maxwell's equations. The model aims to elucidate how the physical properties of electrons and heavy particles affect heat transfer and fluid flow in a lamellar cathode arc. This is achieved by solving and comparing the fields of electron temperature, heavy particle temperature, fluid flow, current density, and Lorentz force distribution under varying welding currents. The results show that the guiding effect of the lamellar cathode on current density, the inertial drag effect of moving arc, and the attraction effect of Lorentz force at the lamellar cathode tip primarily govern the distribution of the arc's physical fields. The guiding effect localizes the current density to the front end of the lamellar cathode, particularly where the discharge gap is minimal. Both the inertial drag effect and the attraction effect of Lorentz force direct arc flow toward its periphery. Under the influence of the aforementioned factors, the physical fields of the lamellar cathode arc undergo expansion and shift counter to the arc's direction of motion. A reduction in welding current substantially weakens the guiding effect, causing the arc's physical fields to deviate further in the direction opposite to the arc motion. In comparison with a cylindrical cathode arc, the physical fields of the lamellar cathode arc are markedly expanded, leading to a reduction in current density, electron temperature, heavy particle temperature, cathode jet flow velocity, and Lorentz force.
{"title":"Two-temperature modeling of lamellar cathode arc","authors":"Yuanbo Li, Xing Liu, T. Ye","doi":"10.1088/2058-6272/ad2d0e","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2d0e","url":null,"abstract":"\u0000 A three-dimensional, two-temperature (2T) model of a lamellar cathode arc is constructed, drawing upon the conservation equations for mass, momentum, electron energy, and heavy particle energy, in addition to Maxwell's equations. The model aims to elucidate how the physical properties of electrons and heavy particles affect heat transfer and fluid flow in a lamellar cathode arc. This is achieved by solving and comparing the fields of electron temperature, heavy particle temperature, fluid flow, current density, and Lorentz force distribution under varying welding currents. The results show that the guiding effect of the lamellar cathode on current density, the inertial drag effect of moving arc, and the attraction effect of Lorentz force at the lamellar cathode tip primarily govern the distribution of the arc's physical fields. The guiding effect localizes the current density to the front end of the lamellar cathode, particularly where the discharge gap is minimal. Both the inertial drag effect and the attraction effect of Lorentz force direct arc flow toward its periphery. Under the influence of the aforementioned factors, the physical fields of the lamellar cathode arc undergo expansion and shift counter to the arc's direction of motion. A reduction in welding current substantially weakens the guiding effect, causing the arc's physical fields to deviate further in the direction opposite to the arc motion. In comparison with a cylindrical cathode arc, the physical fields of the lamellar cathode arc are markedly expanded, leading to a reduction in current density, electron temperature, heavy particle temperature, cathode jet flow velocity, and Lorentz force.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"138 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140429275","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 : 2024-02-25DOI: 10.1088/2058-6272/ad2ce0
Lanping Wang, L. Nie, Xinpei Lu
OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma (NAPP), which plays important role in applications such as plasma medicine. However, the experimental studies on how the gas content affects the post-discharge temporal evolution of OH and O in the noble gas ns-NAPP are very limit. In this paper, the effect of the percentage of O2, N2, and H2O on the amount of OH and O production and their post-discharge temporal behavior in ns-NAPP is investigated by Laser-induced fluorescence (LIF) method. The results show that the production of OH and O increases and then decreases with the increase of O2 percentage. Both OH and O densities reach their maximum when about 0.8% O2 is added. Further increase the O2 concentration results in the decrease of the initial densities of both OH and O, and leads to their faster decay. With the increase of N2 percentage, it also results in the increase and then decrease of the OH and O densities, but the change is smaller. Furthermore, when the H2O concentration is increased from 100 ppm to 3000 ppm, the initial OH density increases slightly, but the OH density decays much faster. While the initial density of O decreases with the increase of the H2O concentration. After analysis, it is found that OH and O are mainly produced through electron collisional dissociation. O (1D) is critical for OH generation. O3 accelerates the consumption process of OH and O at high O2 percentage. The addition of H2O in the NAPP considerably enhances the electronegativity, while it decreases the overall plasma reactivity, accelerates the decay of OH and reduces the O atom density.
OH自由基和O原子是非平衡常压等离子体（NAPP）中最重要的两种反应物，在等离子体医学等应用中发挥着重要作用。然而，关于气体含量如何影响惰性气体 ns-NAPP 中 OH 和 O 的放电后时间演化的实验研究非常有限。本文采用激光诱导荧光（LIF）方法研究了 O2、N2 和 H2O 的比例对 ns-NAPP 中 OH 和 O 生成量及其放电后时间行为的影响。结果表明，随着 O2 比例的增加，OH 和 O 的产生量先增加后减少。当加入约 0.8% 的氧气时，OH 和 O 的密度都达到最大值。进一步增加氧气浓度会导致 OH 和 O 的初始密度降低，并加速其衰减。随着 N2 百分比的增加，也会导致 OH 和 O 的密度先增大后减小，但变化较小。此外，当 H2O 浓度从 100 ppm 增加到 3000 ppm 时，初始 OH 密度略有增加，但 OH 密度的衰减速度更快。而 O 的初始密度则随着 H2O 浓度的增加而降低。经过分析发现，OH 和 O 主要是通过电子碰撞解离产生的。O (1D) 是产生 OH 的关键。在 O2 比例较高时，O3 会加速 OH 和 O 的消耗过程。在 NAPP 中加入 H2O 会大大提高电负性，同时降低整个等离子体的反应性，加速 OH 的衰变并降低 O 原子密度。
{"title":"Effect of gas components on the post-discharge temporal behavior of OH and O of a non-equilibrium atmospheric pressure plasma driven by nanosecond voltage pulses","authors":"Lanping Wang, L. Nie, Xinpei Lu","doi":"10.1088/2058-6272/ad2ce0","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2ce0","url":null,"abstract":"\u0000 OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma (NAPP), which plays important role in applications such as plasma medicine. However, the experimental studies on how the gas content affects the post-discharge temporal evolution of OH and O in the noble gas ns-NAPP are very limit. In this paper, the effect of the percentage of O2, N2, and H2O on the amount of OH and O production and their post-discharge temporal behavior in ns-NAPP is investigated by Laser-induced fluorescence (LIF) method. The results show that the production of OH and O increases and then decreases with the increase of O2 percentage. Both OH and O densities reach their maximum when about 0.8% O2 is added. Further increase the O2 concentration results in the decrease of the initial densities of both OH and O, and leads to their faster decay. With the increase of N2 percentage, it also results in the increase and then decrease of the OH and O densities, but the change is smaller. Furthermore, when the H2O concentration is increased from 100 ppm to 3000 ppm, the initial OH density increases slightly, but the OH density decays much faster. While the initial density of O decreases with the increase of the H2O concentration. After analysis, it is found that OH and O are mainly produced through electron collisional dissociation. O (1D) is critical for OH generation. O3 accelerates the consumption process of OH and O at high O2 percentage. The addition of H2O in the NAPP considerably enhances the electronegativity, while it decreases the overall plasma reactivity, accelerates the decay of OH and reduces the O atom density.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"17 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140433266","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 : 2024-02-22DOI: 10.1088/2058-6272/ad2c3e
Mingzhi Zhao, Xiaoping Li, G. Dong, Xu Liu, Xiangchao Mu
Radar cross-section (RCS) reduction technology is the key to stealth technology. In order to improve the RCS reduction effect of a designed checkerboard metasurface and overcome the limitation of thin-layer plasma in RCS reduction technology, a double-layer-plasma-based metasurface—composed of a checkerboard metasurface, a double-layer plasma, and an air gap between them—was investigated. Based on the principle of backscattering cancellation, we designed a checkerboard metasurface composed of different artificial magnetic conductor (AMC) units, the checkerboard metasurface can make vertically incident electromagnetic (EM) waves be reflected into four different inclined directions to achieve a RCS reduction. Full-wave simulations confirm that the double-layer-plasma-based metasurface can improve the RCS reduction effect of the metasurface and the plasma. The reason is that, in a band lower than the working band of the metasurface, the RCS reduction effect is mainly improved by the plasma layer. In the working band of the metasurface, the impedance mismatching between the air gap and first plasma layer, and the impedance mismatching between first and second plasma layers cause the scattered waves to become more dispersed, so the propagation path of the EM waves in the plasma becomes longer, increasing the absorption of the EM waves by the plasma. Thus, the RCS reduction effect is enhanced. The double-layer-plasma-based metasurface can be insensitive to the polarization of the incoming EM waves, and it can also maintain a satisfactory RCS reduction band when the incident waves are oblique.
{"title":"Wideband RCS reduction by double-layer-plasma-based metasurface","authors":"Mingzhi Zhao, Xiaoping Li, G. Dong, Xu Liu, Xiangchao Mu","doi":"10.1088/2058-6272/ad2c3e","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2c3e","url":null,"abstract":"\u0000 Radar cross-section (RCS) reduction technology is the key to stealth technology. In order to improve the RCS reduction effect of a designed checkerboard metasurface and overcome the limitation of thin-layer plasma in RCS reduction technology, a double-layer-plasma-based metasurface—composed of a checkerboard metasurface, a double-layer plasma, and an air gap between them—was investigated. Based on the principle of backscattering cancellation, we designed a checkerboard metasurface composed of different artificial magnetic conductor (AMC) units, the checkerboard metasurface can make vertically incident electromagnetic (EM) waves be reflected into four different inclined directions to achieve a RCS reduction. Full-wave simulations confirm that the double-layer-plasma-based metasurface can improve the RCS reduction effect of the metasurface and the plasma. The reason is that, in a band lower than the working band of the metasurface, the RCS reduction effect is mainly improved by the plasma layer. In the working band of the metasurface, the impedance mismatching between the air gap and first plasma layer, and the impedance mismatching between first and second plasma layers cause the scattered waves to become more dispersed, so the propagation path of the EM waves in the plasma becomes longer, increasing the absorption of the EM waves by the plasma. Thus, the RCS reduction effect is enhanced. The double-layer-plasma-based metasurface can be insensitive to the polarization of the incoming EM waves, and it can also maintain a satisfactory RCS reduction band when the incident waves are oblique.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"24 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140441079","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 : 2024-02-20DOI: 10.1088/2058-6272/ad2b38
Yun Ling, D. Dai, Jiaxin Chang, Buang Wang
Atmospheric pressure plasma-liquid interactions exist in a variety of applications, including wastewater treatment, wound sterilization, and disinfection. In practice, the phenomenon of liquid surface depression will inevitably appear. The applied gas will cause a depression on the liquid surface, which will undoubtedly affect the plasma generation and further affect the application performance. However, the effect of liquid surface deformation on the plasma is still unclear. In this study, numerical models are developed to reveal the mechanism of liquid surface depressions affecting plasma discharge characteristics and the consequential distribution of plasma species, and further study the influence of liquid surface depressions of different sizes generated by different helium flow rates on the plasma. Results show that the liquid surface deformation changes the initial spatial electric field, resulting in the rearrangement of electrons on the liquid surface. The charges deposited on the liquid surface further increase the degree of distortion of the electric field. Moreover, the electric field and electron distribution affected by the liquid surface depression significantly influence the generation and distribution of active species, which determines the practical effectiveness of the relevant applications. This work explores the phenomenon of liquid surface depression, which has been neglected in previous related work, and contributes to further understanding of plasma-liquid interactions, providing better theoretical guidance for related applications and technologies.
{"title":"Effect of liquid surface depression size on discharge characteristics and chemical distribution in the plasma-liquid anode system","authors":"Yun Ling, D. Dai, Jiaxin Chang, Buang Wang","doi":"10.1088/2058-6272/ad2b38","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2b38","url":null,"abstract":"\u0000 Atmospheric pressure plasma-liquid interactions exist in a variety of applications, including wastewater treatment, wound sterilization, and disinfection. In practice, the phenomenon of liquid surface depression will inevitably appear. The applied gas will cause a depression on the liquid surface, which will undoubtedly affect the plasma generation and further affect the application performance. However, the effect of liquid surface deformation on the plasma is still unclear. In this study, numerical models are developed to reveal the mechanism of liquid surface depressions affecting plasma discharge characteristics and the consequential distribution of plasma species, and further study the influence of liquid surface depressions of different sizes generated by different helium flow rates on the plasma. Results show that the liquid surface deformation changes the initial spatial electric field, resulting in the rearrangement of electrons on the liquid surface. The charges deposited on the liquid surface further increase the degree of distortion of the electric field. Moreover, the electric field and electron distribution affected by the liquid surface depression significantly influence the generation and distribution of active species, which determines the practical effectiveness of the relevant applications. This work explores the phenomenon of liquid surface depression, which has been neglected in previous related work, and contributes to further understanding of plasma-liquid interactions, providing better theoretical guidance for related applications and technologies.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"41 30","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140449011","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}
The characteristics of blue core phenomenon observed in a divergent magnetic field helicon plasma is investigated by using two different helical antennas, namely, right-handed (RH) and left-handed (LH) helical antennas. The mode transition, discharge image, spatial profiles of plasma density and electron temperature are diagnosed by using a Langmuir probe, a Nikon D90 camera, an intensified charge-coupled device (ICCD) camera, and an optical emission spectrometer (OES), respectively. The results demonstrated that the blue core phenomenon appeared in the upstream region of the discharge tube at a fixed magnetic field under both helical antennas. However, it is more likely to appear in the situation of RH helical antenna, in which the plasma density and ionization rate of helicon plasma are higher. The spatial profiles of the plasma density and the electron temperature are also different both in axial and radial directions for these two kinds of helical antennas. The wavelength calculated based on the dispersion relation of the bounded whistler wave is consistent with the order of magnitude of plasma length. It is proved that the helicon plasma is in the wave mode discharge mechanism.
{"title":"Effect of antenna helicity on discharge characteristics of helicon plasma under divergent magnetic field","authors":"Meng Sun, Xiaofang Xu, Chenwen Wang, Xianyi Yin, Qiang Chen, Haibao Zhang","doi":"10.1088/2058-6272/ad2b37","DOIUrl":"https://doi.org/10.1088/2058-6272/ad2b37","url":null,"abstract":"\u0000 The characteristics of blue core phenomenon observed in a divergent magnetic field helicon plasma is investigated by using two different helical antennas, namely, right-handed (RH) and left-handed (LH) helical antennas. The mode transition, discharge image, spatial profiles of plasma density and electron temperature are diagnosed by using a Langmuir probe, a Nikon D90 camera, an intensified charge-coupled device (ICCD) camera, and an optical emission spectrometer (OES), respectively. The results demonstrated that the blue core phenomenon appeared in the upstream region of the discharge tube at a fixed magnetic field under both helical antennas. However, it is more likely to appear in the situation of RH helical antenna, in which the plasma density and ionization rate of helicon plasma are higher. The spatial profiles of the plasma density and the electron temperature are also different both in axial and radial directions for these two kinds of helical antennas. The wavelength calculated based on the dispersion relation of the bounded whistler wave is consistent with the order of magnitude of plasma length. It is proved that the helicon plasma is in the wave mode discharge mechanism.","PeriodicalId":506986,"journal":{"name":"Plasma Science and Technology","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140447520","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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