Pub Date : 2024-09-18DOI: 10.1088/1361-6595/ad6fcc
Ryan Park, Brett S Scheiner and Mark C Zammit
Plasma-neutral interactions, including reactive kinetics, are often either studied in 0D using ODE-based descriptions, or in multi-dimensional fluid or particle-based plasma codes. The latter case involves a complex assembly of procedures that are not always necessary to test effects of underlying physical models and mechanisms for particle-based descriptions. Here we present ThunderBoltz, a lightweight, publicly available 0D direct simulation Monte Carlo code designed to accommodate a generalized combination of species and arbitrary cross sections without the overhead of expensive field solves. It can produce electron, ion, and neutral velocity distributions in applied AC/DC E-field and/or static B-field scenarios. The code is built in the C++ standard library and includes a convenient Python interface that allows for input file generation (including compatibility with cross section data from the LXCat database), electron transport and reaction rate constant post-processing, input parameter constraint satisfaction, calculation scheduling, and diagnostic plotting. These codes can be accessed at the repository: https://github.com/lanl/ThunderBoltz. In this work we compare ThunderBoltz transport calculations against Bolsig+ calculations, benchmark test problems, and swarm experiment data, finding good agreement with all three in the appropriate field regimes. In addition, we present example use cases where the electron, ion, and background neutral particle species are self-consistently evolved to model the background kinetics, a feature that is absent in fixed-background Monte Carlo and n-term Boltzmann solvers. The latter functionality allows for the possibility of particle-based chemical kinetics simulations of the plasma and neutral species as a new alternative to ODE-based approaches.
等离子体与中性的相互作用，包括反应动力学，通常在 0D 条件下使用基于 ODE 的描述进行研究，或者在多维流体或基于粒子的等离子体代码中进行研究。后一种情况涉及复杂的程序组合，而这些程序并不总是测试基于粒子描述的基本物理模型和机制的效果所必需的。我们在此介绍 ThunderBoltz，这是一种轻量级、公开可用的 0D 直接模拟蒙特卡洛代码，旨在适应物种和任意截面的通用组合，而无需昂贵的场求解开销。它可以在应用交直流电子场和/或静态 B 场的情况下生成电子、离子和中性速度分布。代码采用 C++ 标准库构建，包括一个方便的 Python 接口，可用于生成输入文件（包括与 LXCat 数据库中的截面数据兼容）、电子传输和反应速率常数后处理、输入参数约束满足、计算调度和诊断绘图。这些代码可在 https://github.com/lanl/ThunderBoltz 存储库中访问。在这项工作中，我们将 ThunderBoltz 的输运计算与 Bolsig+ 计算、基准测试问题和蜂群实验数据进行了比较，发现在适当的场域条件下，三者之间的一致性都很好。此外，我们还举例说明了电子、离子和背景中性粒子物种自洽进化以模拟背景动力学的使用案例，这是固定背景蒙特卡洛和 n 期玻尔兹曼求解器所不具备的功能。后一种功能允许对等离子体和中性粒子进行基于粒子的化学动力学模拟，作为基于 ODE 方法的新替代方法。
{"title":"ThunderBoltz: an open-source direct simulation Monte Carlo Boltzmann solver for plasma transport, chemical kinetics, and 0D modeling","authors":"Ryan Park, Brett S Scheiner and Mark C Zammit","doi":"10.1088/1361-6595/ad6fcc","DOIUrl":"https://doi.org/10.1088/1361-6595/ad6fcc","url":null,"abstract":"Plasma-neutral interactions, including reactive kinetics, are often either studied in 0D using ODE-based descriptions, or in multi-dimensional fluid or particle-based plasma codes. The latter case involves a complex assembly of procedures that are not always necessary to test effects of underlying physical models and mechanisms for particle-based descriptions. Here we present ThunderBoltz, a lightweight, publicly available 0D direct simulation Monte Carlo code designed to accommodate a generalized combination of species and arbitrary cross sections without the overhead of expensive field solves. It can produce electron, ion, and neutral velocity distributions in applied AC/DC E-field and/or static B-field scenarios. The code is built in the C++ standard library and includes a convenient Python interface that allows for input file generation (including compatibility with cross section data from the LXCat database), electron transport and reaction rate constant post-processing, input parameter constraint satisfaction, calculation scheduling, and diagnostic plotting. These codes can be accessed at the repository: https://github.com/lanl/ThunderBoltz. In this work we compare ThunderBoltz transport calculations against Bolsig+ calculations, benchmark test problems, and swarm experiment data, finding good agreement with all three in the appropriate field regimes. In addition, we present example use cases where the electron, ion, and background neutral particle species are self-consistently evolved to model the background kinetics, a feature that is absent in fixed-background Monte Carlo and n-term Boltzmann solvers. The latter functionality allows for the possibility of particle-based chemical kinetics simulations of the plasma and neutral species as a new alternative to ODE-based approaches.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142266598","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 : 2024-09-18DOI: 10.1088/1361-6595/ad75b2
Zilin Huang, Yuan Hu, Jinyue Geng, Chao Yang and Quanhua Sun
The present work develops a full particle-based model that couples the particle-in-cell plus Monte Carlo collision (PIC-MCC) simulation for plasma dynamics and the direct simulation Monte Carlo (DSMC) method for neutral dynamics in a synergistic iterative manner. This new model overcomes the slow convergence issue in the conventional direct coupling approach caused by the disparity of the time scales between the plasma and neutral dynamics. This model is applied to simulate the behavior of xenon (Xe) and its potential alternatives, krypton (Kr) and argon (Ar), in the discharge chamber of a miniature direct current (DC) ion thruster. The results show that a stable discharge is difficult to achieve for Kr and Ar under the operating conditions optimal for Xe. While increasing the discharge voltage can effectively improve the stability of discharge for Kr and Ar, other common strategies such as changing the magnetic field strength, propellant flow rate, and cathode current are not successful. The propellant utilization efficiency and discharge efficiency are affected by both discharge voltage and propellant flow rate. A maximum utilization efficiency and an optimal discharge efficiency are observed for all three propellants, with the values decreasing in the order of Xe, Kr, and Ar. Moreover, the discharge voltage corresponding to the optimal efficiency is inversely proportional to the square root of the propellant mass, indicating that the ion diffusional loss to the wall, rather than the ionization energy, is the dominant factor affecting the discharge performance for alternative propellants in a miniature DC thruster.
本研究建立了一个基于粒子的完整模型，以协同迭代的方式将等离子体动力学的粒子入胞加蒙特卡洛碰撞（PIC-MCC）模拟与中性动力学的直接模拟蒙特卡洛（DSMC）方法结合起来。这一新模型克服了传统直接耦合方法因等离子体和中性动力学的时间尺度不同而导致的收敛缓慢问题。该模型被用于模拟氙（Xe）及其潜在替代品氪（Kr）和氩（Ar）在微型直流（DC）离子推进器放电室中的行为。结果表明，在 Xe 的最佳工作条件下，Kr 和 Ar 很难实现稳定放电。虽然增加放电电压可以有效提高 Kr 和 Ar 的放电稳定性，但其他常用策略，如改变磁场强度、推进剂流速和阴极电流等，并不奏效。推进剂利用效率和放电效率受放电电压和推进剂流速的影响。对于所有三种推进剂，都能观察到最大利用效率和最佳放电效率，其值依次为 Xe、Kr 和 Ar。此外，与最佳效率相对应的放电电压与推进剂质量的平方根成反比，这表明在微型直流推进器中，影响替代推进剂放电性能的主要因素是离子向器壁的扩散损耗，而不是电离能。
{"title":"Kinetic investigation of discharge performance for Xe, Kr, and Ar in a miniature ion thruster using a fast converging PIC-MCC-DSMC model","authors":"Zilin Huang, Yuan Hu, Jinyue Geng, Chao Yang and Quanhua Sun","doi":"10.1088/1361-6595/ad75b2","DOIUrl":"https://doi.org/10.1088/1361-6595/ad75b2","url":null,"abstract":"The present work develops a full particle-based model that couples the particle-in-cell plus Monte Carlo collision (PIC-MCC) simulation for plasma dynamics and the direct simulation Monte Carlo (DSMC) method for neutral dynamics in a synergistic iterative manner. This new model overcomes the slow convergence issue in the conventional direct coupling approach caused by the disparity of the time scales between the plasma and neutral dynamics. This model is applied to simulate the behavior of xenon (Xe) and its potential alternatives, krypton (Kr) and argon (Ar), in the discharge chamber of a miniature direct current (DC) ion thruster. The results show that a stable discharge is difficult to achieve for Kr and Ar under the operating conditions optimal for Xe. While increasing the discharge voltage can effectively improve the stability of discharge for Kr and Ar, other common strategies such as changing the magnetic field strength, propellant flow rate, and cathode current are not successful. The propellant utilization efficiency and discharge efficiency are affected by both discharge voltage and propellant flow rate. A maximum utilization efficiency and an optimal discharge efficiency are observed for all three propellants, with the values decreasing in the order of Xe, Kr, and Ar. Moreover, the discharge voltage corresponding to the optimal efficiency is inversely proportional to the square root of the propellant mass, indicating that the ion diffusional loss to the wall, rather than the ionization energy, is the dominant factor affecting the discharge performance for alternative propellants in a miniature DC thruster.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142266599","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 : 2024-09-16DOI: 10.1088/1361-6595/ad75b3
Cheng Luo, Jia Zhang, Yanming Liu, Qiang Wei, Mengjia Dang, Yongshan Ba, Jingru Gao and Yuxin Li
A plasma sheath will be generated around the hypersonic vehicle during reentry, where a large number of electrons will significantly affect the propagation of EM waves, resulting in the phenomenon of communication blackout. This paper proposes a method of reducing the electron density of reentry vehicle plasma sheath by pulsed discharge. Experiments were conducted in a high-speed plasma wind tunnel to study the effects and scope of pulsed discharge on the plasma sheath electron density using an ultrahigh-speed camera and microwave diagnostic system. The experimental results show that the application of pulsed discharge resulted in the formation of a light intensity attenuation region measuring 14 × 19 × 4 cm around the discharge area, with an attenuation degree ranging from 30% to 58%. The microwave diagnostic results indicate that after the actuator discharge, the electron density of the plasma sheath within a 4 cm height above the vehicle wall is significantly reduced compared to before the actuator discharge, with a maximum reduction of approximately 86%. These results demonstrate that this method has significant effects on reducing plasma sheath electron density. Furthermore, the low power consumption, load, and space requirements suggest that it has potential for practical applications.
{"title":"Ground experimental study of the electron density of plasma sheath reduced by pulsed discharge","authors":"Cheng Luo, Jia Zhang, Yanming Liu, Qiang Wei, Mengjia Dang, Yongshan Ba, Jingru Gao and Yuxin Li","doi":"10.1088/1361-6595/ad75b3","DOIUrl":"https://doi.org/10.1088/1361-6595/ad75b3","url":null,"abstract":"A plasma sheath will be generated around the hypersonic vehicle during reentry, where a large number of electrons will significantly affect the propagation of EM waves, resulting in the phenomenon of communication blackout. This paper proposes a method of reducing the electron density of reentry vehicle plasma sheath by pulsed discharge. Experiments were conducted in a high-speed plasma wind tunnel to study the effects and scope of pulsed discharge on the plasma sheath electron density using an ultrahigh-speed camera and microwave diagnostic system. The experimental results show that the application of pulsed discharge resulted in the formation of a light intensity attenuation region measuring 14 × 19 × 4 cm around the discharge area, with an attenuation degree ranging from 30% to 58%. The microwave diagnostic results indicate that after the actuator discharge, the electron density of the plasma sheath within a 4 cm height above the vehicle wall is significantly reduced compared to before the actuator discharge, with a maximum reduction of approximately 86%. These results demonstrate that this method has significant effects on reducing plasma sheath electron density. Furthermore, the low power consumption, load, and space requirements suggest that it has potential for practical applications.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142266553","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 : 2024-09-12DOI: 10.1088/1361-6595/ad75b5
Hao Wu, Ran An, Can Jiang, Dong Zhong, Wei Jiang and Ya Zhang
This paper constitutes the second part of a two-part series investigating the breakdown modes of capacitively coupled plasma across varying pressures, employing an implicit particle-in-cell/Monte Carlo collision model. This segment focuses on non-self-sustained modes, namely normal failure discharge (NFD), bias failure discharge (BFD), and runaway failure discharge (RFD). NFD results from a failed electron avalanche, BFD stems from the charging effect of the blocking capacitor, and RFD arises from a decrease in electron emission rate during sheath formation. The effects of background pressure and voltage on these failure discharges are examined and analyzed. The RFD, which leads to periodic electron avalanches, is discussed in detail. Studying these non-self-sustained cases facilitates understanding the reasons for failure discharge in extremely low-pressure environments and determining the parameter limits of self-sustained discharge, crucial for preventing plasma cracks, enhancing equipment product yield, and ensuring equipment safety, thereby mitigating industrial losses.
{"title":"Breakdown modes of capacitively coupled plasma: II. Non-self-sustained discharges","authors":"Hao Wu, Ran An, Can Jiang, Dong Zhong, Wei Jiang and Ya Zhang","doi":"10.1088/1361-6595/ad75b5","DOIUrl":"https://doi.org/10.1088/1361-6595/ad75b5","url":null,"abstract":"This paper constitutes the second part of a two-part series investigating the breakdown modes of capacitively coupled plasma across varying pressures, employing an implicit particle-in-cell/Monte Carlo collision model. This segment focuses on non-self-sustained modes, namely normal failure discharge (NFD), bias failure discharge (BFD), and runaway failure discharge (RFD). NFD results from a failed electron avalanche, BFD stems from the charging effect of the blocking capacitor, and RFD arises from a decrease in electron emission rate during sheath formation. The effects of background pressure and voltage on these failure discharges are examined and analyzed. The RFD, which leads to periodic electron avalanches, is discussed in detail. Studying these non-self-sustained cases facilitates understanding the reasons for failure discharge in extremely low-pressure environments and determining the parameter limits of self-sustained discharge, crucial for preventing plasma cracks, enhancing equipment product yield, and ensuring equipment safety, thereby mitigating industrial losses.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210056","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 : 2024-09-12DOI: 10.1088/1361-6595/ad75b4
Hao Wu, Ran An, Dong Zhong, Wei Jiang and Ya Zhang
This paper is the first in a two-part series that simulates the breakdown modes of capacitively coupled plasmas (CCPs) across various pressures using an implicit particle-in-cell/Monte Carlo collision model. The study identifies several discharge modes in the lower pressure region, including three self-sustained discharges: glow discharge, normal multipactor, and abnormal multipactor, as well as various non-self-sustained discharges. This part focuses on the formation and transitions of self-sustained modes, specifically detailing how the glow discharge transitions into an abnormal multipactor below 2 mTorr, which then evolves into a normal multipactor within a narrow voltage range. The characteristics and formation processes of these self-sustained discharges are explored, emphasizing their reliance on higher electron emission rates and high-frequency RF power. The emergence of multipactor discharges in the 60 MHz range potentially expands the gas discharge theory and broadens the application scope of CCPs.
{"title":"Breakdown modes of capacitively coupled plasma: I. Transitions from glow discharge to multipactor","authors":"Hao Wu, Ran An, Dong Zhong, Wei Jiang and Ya Zhang","doi":"10.1088/1361-6595/ad75b4","DOIUrl":"https://doi.org/10.1088/1361-6595/ad75b4","url":null,"abstract":"This paper is the first in a two-part series that simulates the breakdown modes of capacitively coupled plasmas (CCPs) across various pressures using an implicit particle-in-cell/Monte Carlo collision model. The study identifies several discharge modes in the lower pressure region, including three self-sustained discharges: glow discharge, normal multipactor, and abnormal multipactor, as well as various non-self-sustained discharges. This part focuses on the formation and transitions of self-sustained modes, specifically detailing how the glow discharge transitions into an abnormal multipactor below 2 mTorr, which then evolves into a normal multipactor within a narrow voltage range. The characteristics and formation processes of these self-sustained discharges are explored, emphasizing their reliance on higher electron emission rates and high-frequency RF power. The emergence of multipactor discharges in the 60 MHz range potentially expands the gas discharge theory and broadens the application scope of CCPs.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210054","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}
Doping a small amount of ethanol gas (EtOH) in argon can change the argon plasma jet from filamentary discharge mode to diffuse discharge mode, and further doping of trace oxygen can significantly enhance the composition and content of oxygen-containing active particles in the argon plasma. Based on this, the discharge characteristics of Ar + EtOH plasma jet under different concentrations of oxygen doping and its effect on the surface modification effect of polyimide (PI) films were investigated in this paper. It was found that the discharge characteristics of Ar + EtOH + O2 plasma jet deteriorate with the increase of oxygen doping concentration, but the oxygen doping concentration of 0–4000 ppm can still be stable, diffuse and the gas temperature is close to room temperature. Through the water contact angle (WCA) measurement and peel strength test, it was found that when the oxygen doping concentration was 800 ppm, the Ar + EtOH + O2 plasma jet treatment for 180 s had the best effect on the improvement of surface wettability and adhesion of the PI films, and the WCA was reduced from ∼71.9° to ∼17.6°. At the same time, the peel strength was increased from 122 N m−1 to 418 N m−1, which is an increase of ∼243%. Combined with the material characterization analysis, it was found that the surface roughness of the PI films was enhanced and more C–O and C=O bonds were grafted on the surface after the Ar + EtOH + O2 plasma jet treatment. Finally, through the two-dimensional axisymmetric argon-doped ethanol plasma jet hydrodynamic simulation analysis, it was found that when the working gas Ar + EtOH was doped with 800 ppm O2, the number density of OH did not change much, but the number density of O2− was about 6 orders of magnitude higher than that of the non-doped O2. The mechanism that Ar + EtOH + O2 plasma jet could improve more wettability and bonding of PI films in a shorter treatment time was revealed.
在氩气中掺入少量乙醇（EtOH）可使氩等离子体射流从丝状放电模式变为弥散放电模式，而进一步掺入微量氧可显著提高氩等离子体中含氧活性粒子的成分和含量。基于此，本文研究了不同掺氧浓度下 Ar + EtOH 等离子体射流的放电特性及其对聚酰亚胺（PI）薄膜表面改性效果的影响。研究发现，Ar + EtOH + O2 等离子体射流的放电特性随氧掺杂浓度的增加而变差，但氧掺杂浓度为 0-4000 ppm 时仍能保持稳定的扩散性，且气体温度接近室温。通过水接触角（WCA）测量和剥离强度测试发现，当氧掺杂浓度为 800 ppm 时，Ar + EtOH + O2 等离子体喷射处理 180 s 对 PI 薄膜表面润湿性和附着力的改善效果最好，WCA 从 ∼71.9° 降低到 ∼17.6° 。同时，剥离强度从 122 N m-1 提高到 418 N m-1，提高了 ∼243%。结合材料表征分析发现，经 Ar + EtOH + O2 等离子喷射处理后，PI 薄膜的表面粗糙度提高，表面接枝了更多的 C-O 和 C=O 键。最后，通过二维轴对称掺氩乙醇等离子体射流流体力学模拟分析发现，当工作气体 Ar + EtOH 掺杂 800 ppm O2 时，OH 的数量密度变化不大，但 O2- 的数量密度比未掺杂 O2 时高约 6 个数量级。这揭示了 Ar + EtOH + O2 等离子射流能在更短的处理时间内改善 PI 薄膜的润湿性和结合力的机理。
{"title":"Effect of oxygen on the discharge characteristics of argon doped ethanol plasma jet and its application in surface modification of polyimide films","authors":"Jianqiang Jiao, Wenjie Xia, Jinxin Wu, Bin He, Hao Tian, Yifan Liu, Guizhi Xu","doi":"10.1088/1361-6595/ad716b","DOIUrl":"https://doi.org/10.1088/1361-6595/ad716b","url":null,"abstract":"Doping a small amount of ethanol gas (EtOH) in argon can change the argon plasma jet from filamentary discharge mode to diffuse discharge mode, and further doping of trace oxygen can significantly enhance the composition and content of oxygen-containing active particles in the argon plasma. Based on this, the discharge characteristics of Ar + EtOH plasma jet under different concentrations of oxygen doping and its effect on the surface modification effect of polyimide (PI) films were investigated in this paper. It was found that the discharge characteristics of Ar + EtOH + O<sub>2</sub> plasma jet deteriorate with the increase of oxygen doping concentration, but the oxygen doping concentration of 0–4000 ppm can still be stable, diffuse and the gas temperature is close to room temperature. Through the water contact angle (WCA) measurement and peel strength test, it was found that when the oxygen doping concentration was 800 ppm, the Ar + EtOH + O<sub>2</sub> plasma jet treatment for 180 s had the best effect on the improvement of surface wettability and adhesion of the PI films, and the WCA was reduced from ∼71.9° to ∼17.6°. At the same time, the peel strength was increased from 122 N m<sup>−1</sup> to 418 N m<sup>−1</sup>, which is an increase of ∼243%. Combined with the material characterization analysis, it was found that the surface roughness of the PI films was enhanced and more C–O and C=O bonds were grafted on the surface after the Ar + EtOH + O<sub>2</sub> plasma jet treatment. Finally, through the two-dimensional axisymmetric argon-doped ethanol plasma jet hydrodynamic simulation analysis, it was found that when the working gas Ar + EtOH was doped with 800 ppm O<sub>2</sub>, the number density of OH did not change much, but the number density of O<sub>2</sub><sup>−</sup> was about 6 orders of magnitude higher than that of the non-doped O<sub>2</sub>. The mechanism that Ar + EtOH + O<sub>2</sub> plasma jet could improve more wettability and bonding of PI films in a shorter treatment time was revealed.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"409 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210058","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 : 2024-09-02DOI: 10.1088/1361-6595/ad6fcf
Zhengyan Liu, Yoichi Hirakawa, Kazuto Yamamoto, Terumasa Ryu, Jie Li, Nan Jiang, Takao Namihira, Douyan Wang
Understanding the rapid dynamics of the primary streamer is crucial for comprehending the nanosecond pulsed discharge process. To reveal the fast primary streamer process, this study introduces a newly developed quadruple emICCD camera system capable of capturing a sequence of four discharge images in single pulse, coupled with self-customized software for data analysis. A nanosecond pulse power with its FWHM of 10.5 ns was applied to a coaxial reactor, focusing on the dynamics of the primary streamer. Our research clarifies the spatiotemporal variations of the primary streamer’s properties and examines their relation with inner electrode diameter (i.d. 0.2–2.0 mm). Results showed that in a pulse-powered coaxial electrode, there are three stages in the primary streamer process and that i.d. serves as an important factor influencing the formation and propagation of streamers. Interestingly, we found that streamer head velocity, streamer width, and streamer area for individual streamers remain constant prior to streamer channels reaching the outer electrode. Furthermore, we also observed an initial increase followed by a decrease in both streamer head velocity and streamer width with increasing i.d values. This study sheds light on the fundamental properties of the primary streamer during nanosecond pulsed discharge, contributing valuable insights for future plasma applications.
{"title":"Consecutive diagnosis of nanosecond pulsed discharge in a coaxial electrode configuration using a quadruple emICCD camera system","authors":"Zhengyan Liu, Yoichi Hirakawa, Kazuto Yamamoto, Terumasa Ryu, Jie Li, Nan Jiang, Takao Namihira, Douyan Wang","doi":"10.1088/1361-6595/ad6fcf","DOIUrl":"https://doi.org/10.1088/1361-6595/ad6fcf","url":null,"abstract":"Understanding the rapid dynamics of the primary streamer is crucial for comprehending the nanosecond pulsed discharge process. To reveal the fast primary streamer process, this study introduces a newly developed quadruple emICCD camera system capable of capturing a sequence of four discharge images in single pulse, coupled with self-customized software for data analysis. A nanosecond pulse power with its FWHM of 10.5 ns was applied to a coaxial reactor, focusing on the dynamics of the primary streamer. Our research clarifies the spatiotemporal variations of the primary streamer’s properties and examines their relation with inner electrode diameter (i.d. 0.2–2.0 mm). Results showed that in a pulse-powered coaxial electrode, there are three stages in the primary streamer process and that i.d. serves as an important factor influencing the formation and propagation of streamers. Interestingly, we found that streamer head velocity, streamer width, and streamer area for individual streamers remain constant prior to streamer channels reaching the outer electrode. Furthermore, we also observed an initial increase followed by a decrease in both streamer head velocity and streamer width with increasing i.d values. This study sheds light on the fundamental properties of the primary streamer during nanosecond pulsed discharge, contributing valuable insights for future plasma applications.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"105 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210076","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 : 2024-08-29DOI: 10.1088/1361-6595/ad6fcd
Kangkang Li, Xiaoting Lei, He Cheng, Wenchao Zhang, Xinpei Lu
The efficiency of plasma-coupled catalysis is believed to be higher than the sum of the efficiencies of the plasma and catalyst when acting independently. However, the underlying microscopic interaction mechanism responsible for this phenomenon remains systematically unexplored. This paper presents an initial demonstration of the combined effects of complex porous-structured catalysts and CO2 plasma using a two-dimensional fluid dynamics model. The study attests to the contribution of the catalyst’s porous structure in enhancing the electric field intensity, facilitating ‘hotspot’ formation, accelerating plasma development, improving ionization rate, as well as increasing the density of electrons, reactive heavy species, and products. It also uncovers the ability of plasma to penetrate into the surface pores of the catalytic bead, and the potential occurrence of micro-discharges within catalyst interior pores. Meanwhile, the reactive species of plasma such as the energetic electrons and the vibrationally/electronically excited CO2 in plasma may also impact the surface processes of the catalyst through mechanisms such as reducing reaction barriers. The successful replication of these interactions underscores the potential of this model as a valuable tool for investigating the efficiency optimization of plasma-enhanced catalytic conversion of CO2.
{"title":"The investigation of synergistic interactions between CO2 plasma and porous catalysts through 2-D fluid modeling","authors":"Kangkang Li, Xiaoting Lei, He Cheng, Wenchao Zhang, Xinpei Lu","doi":"10.1088/1361-6595/ad6fcd","DOIUrl":"https://doi.org/10.1088/1361-6595/ad6fcd","url":null,"abstract":"The efficiency of plasma-coupled catalysis is believed to be higher than the sum of the efficiencies of the plasma and catalyst when acting independently. However, the underlying microscopic interaction mechanism responsible for this phenomenon remains systematically unexplored. This paper presents an initial demonstration of the combined effects of complex porous-structured catalysts and CO<sub>2</sub> plasma using a two-dimensional fluid dynamics model. The study attests to the contribution of the catalyst’s porous structure in enhancing the electric field intensity, facilitating ‘hotspot’ formation, accelerating plasma development, improving ionization rate, as well as increasing the density of electrons, reactive heavy species, and products. It also uncovers the ability of plasma to penetrate into the surface pores of the catalytic bead, and the potential occurrence of micro-discharges within catalyst interior pores. Meanwhile, the reactive species of plasma such as the energetic electrons and the vibrationally/electronically excited CO<sub>2</sub> in plasma may also impact the surface processes of the catalyst through mechanisms such as reducing reaction barriers. The successful replication of these interactions underscores the potential of this model as a valuable tool for investigating the efficiency optimization of plasma-enhanced catalytic conversion of CO<sub>2</sub>.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210077","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 : 2024-08-29DOI: 10.1088/1361-6595/ad6fce
I Simonović, D Bošnjaković, J Teunissen, S Dujko
We have implemented an axisymmetric fluid model of streamers in the AMReX open-source library. Our implementation is based on the first-order fluid model with a local field approximation. Photoionization is implemented by employing the Zhelenznyak’s model using the Helmholtz approach. We have verified our code in standard conditions by comparing our results for positive streamers in air with the existing benchmarks from the literature. To verify the performance of our code in strongly attaching gases, we compare the properties of negative streamers with those obtained from the Afivo-streamer open-source code. Calculations have been performed in mixtures of carbon dioxide and perfluoro-nitrile with a background number density of electrons and positive ions of 1013 m−3. We found an excellent agreement between the two sets of results, which indicates the numerical integrity of our code.
{"title":"Axisymmetric fluid streamer model in the AMReX library","authors":"I Simonović, D Bošnjaković, J Teunissen, S Dujko","doi":"10.1088/1361-6595/ad6fce","DOIUrl":"https://doi.org/10.1088/1361-6595/ad6fce","url":null,"abstract":"We have implemented an axisymmetric fluid model of streamers in the AMReX open-source library. Our implementation is based on the first-order fluid model with a local field approximation. Photoionization is implemented by employing the Zhelenznyak’s model using the Helmholtz approach. We have verified our code in standard conditions by comparing our results for positive streamers in air with the existing benchmarks from the literature. To verify the performance of our code in strongly attaching gases, we compare the properties of negative streamers with those obtained from the Afivo-streamer open-source code. Calculations have been performed in mixtures of carbon dioxide and perfluoro-nitrile with a background number density of electrons and positive ions of 10<sup>13</sup> m<sup>−3</sup>. We found an excellent agreement between the two sets of results, which indicates the numerical integrity of our code.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210078","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 : 2024-08-27DOI: 10.1088/1361-6595/ad6f3f
A Caldarelli, F Filleul, K Takahashi, R W Boswell, C Charles, J E Cater, N Rattenbury
A low-frequency ion instability, with frequency fI between the ion gyrofrequency and the lower hybrid frequency fc,i<fI≪fLH, is detected in an argon plasma expanding in a magnetic nozzle for magnetic fields between 240<Bz,max<700 G. The frequency of the instability exhibits a linear dependence with magnetic field strength, and the wave amplitude has a radial maximum that would match the location of a conical density structure, i.e. high-density cones. For all of the magnetic field cases analysed, the high-frequency spectra showed upper and lower sidebands centred around the driving frequency and at a separation equal to the instability frequency, 27.12 MHz±fI kHz. Measurements of the perpendicular wavenumber would satisfy, for certain magnetic field strengths, the dispersion relation of both an electrostatic ion cyclotron wave (ICW) and of an ion acoustic wave. It is hypothesised that the observed low-frequency wave could be an acoustic-like instability propagating perpendicular to the magnetic field, which develops as an ICW at some magnetic field strengths. From the data collected, it is suggested that the high-frequency sidebands may be caused by modulation of the low-frequency wave.
{"title":"Detection of a low-frequency ion instability in a magnetic nozzle","authors":"A Caldarelli, F Filleul, K Takahashi, R W Boswell, C Charles, J E Cater, N Rattenbury","doi":"10.1088/1361-6595/ad6f3f","DOIUrl":"https://doi.org/10.1088/1361-6595/ad6f3f","url":null,"abstract":"A low-frequency ion instability, with frequency <inline-formula>\u0000<tex-math><?CDATA $f_mathrm{I}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">I</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"psstad6f3fieqn1.gif\"></inline-graphic></inline-formula> between the ion gyrofrequency and the lower hybrid frequency <inline-formula>\u0000<tex-math><?CDATA $f_mathrm{c,i} lt f_mathrm{I} ll f_mathrm{LH}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">c</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant=\"normal\">i</mml:mi></mml:mrow></mml:msub><mml:mo><</mml:mo><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">I</mml:mi></mml:mrow></mml:msub><mml:mo>≪</mml:mo><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mi>LH</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"psstad6f3fieqn2.gif\"></inline-graphic></inline-formula>, is detected in an argon plasma expanding in a magnetic nozzle for magnetic fields between <inline-formula>\u0000<tex-math><?CDATA $240lt B_{zmathrm{,max}}lt 700$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mn>240</mml:mn><mml:mo><</mml:mo><mml:msub><mml:mi>B</mml:mi><mml:mrow><mml:mi>z</mml:mi><mml:mrow><mml:mo>,</mml:mo><mml:mi>max</mml:mi></mml:mrow></mml:mrow></mml:msub><mml:mo><</mml:mo><mml:mn>700</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"psstad6f3fieqn3.gif\"></inline-graphic></inline-formula> G. The frequency of the instability exhibits a linear dependence with magnetic field strength, and the wave amplitude has a radial maximum that would match the location of a conical density structure, i.e. high-density cones. For all of the magnetic field cases analysed, the high-frequency spectra showed upper and lower sidebands centred around the driving frequency and at a separation equal to the instability frequency, 27.12 MHz<inline-formula>\u0000<tex-math><?CDATA $,pm,f_mathrm{I}$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:mo>±</mml:mo><mml:mstyle scriptlevel=\"0\"></mml:mstyle><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">I</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><inline-graphic xlink:href=\"psstad6f3fieqn4.gif\"></inline-graphic></inline-formula> kHz. Measurements of the perpendicular wavenumber would satisfy, for certain magnetic field strengths, the dispersion relation of both an electrostatic ion cyclotron wave (ICW) and of an ion acoustic wave. It is hypothesised that the observed low-frequency wave could be an acoustic-like instability propagating perpendicular to the magnetic field, which develops as an ICW at some magnetic field strengths. From the data collected, it is suggested that the high-frequency sidebands may be caused by modulation of the low-frequency wave.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210079","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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