Pub Date : 2024-02-02DOI: 10.1088/1361-6595/ad257d
G. Arora, P. Hoffer, V. Prukner, Petr Bílek, Milan Šimek
The characteristics of nanosecond discharge propagating along the water-air interface in a unique DBD-like configuration with coplanar electrodes submerged in deionized/tap water are studied by combining ultrafast imaging and emission spectra with electrical characteristics. Time-resolved images provide a clear signature of diffusive plasma excited on the water surface at either side of the blade (insulated plastic separating the anode/cathode) called streamer phase and propagating perpendicularly away from it towards the anode /cathode with different velocities. Later on, the diffusive plasma converts into a few discrete and bright plasma filaments due to ionization instability (spark phase). There is no distinctive dependence in the streamer phase on water conductivity, but in the spark phase, more numerous, brighter, and thicker filaments form in tap water. The time-resolved emission spectra reveal the dominance of the first and second positive system of $mathrm{N_2}$ molecular bands in the streamer phase, followed by the appearance of atomic lines of hydrogen, nitrogen, and oxygen in the spark phase. The emission spectra are utilized to estimate plasma parameters (gas temperature ($T_d$), electric field ($E/N$), and electron density ($n_e$)) where a more dominant spark phase is formed in tap water with $T_dsim1100$ K, $E/N$ $sim800$ Td, and $n_esim10^{18}$ /$rm cm^{-3}$.
{"title":"Properties and characteristics of the nanosecond discharge developing at the water-air interface: tracking evolution from a diffused streamer to a spark filament","authors":"G. Arora, P. Hoffer, V. Prukner, Petr Bílek, Milan Šimek","doi":"10.1088/1361-6595/ad257d","DOIUrl":"https://doi.org/10.1088/1361-6595/ad257d","url":null,"abstract":"\u0000 The characteristics of nanosecond discharge propagating along the water-air interface in a unique DBD-like configuration with coplanar electrodes submerged in deionized/tap water are studied by combining ultrafast imaging and emission spectra with electrical characteristics. Time-resolved images provide a clear signature of diffusive plasma excited on the water surface at either side of the blade (insulated plastic separating the anode/cathode) called streamer phase and propagating perpendicularly away from it towards the anode /cathode with different velocities. Later on, the diffusive plasma converts into a few discrete and bright plasma filaments due to ionization instability (spark phase). There is no distinctive dependence in the streamer phase on water conductivity, but in the spark phase, more numerous, brighter, and thicker filaments form in tap water. The time-resolved emission spectra reveal the dominance of the first and second positive system of $mathrm{N_2}$ molecular bands in the streamer phase, followed by the appearance of atomic lines of hydrogen, nitrogen, and oxygen in the spark phase. The emission spectra are utilized to estimate plasma parameters (gas temperature ($T_d$), electric field ($E/N$), and electron density ($n_e$)) where a more dominant spark phase is formed in tap water with $T_dsim1100$ K, $E/N$ $sim800$ Td, and $n_esim10^{18}$ /$rm cm^{-3}$.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"52 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810252","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 : 2024-02-02DOI: 10.1088/1361-6595/ad257e
M. Acciarri, Chris Hudson Moore, Scott D Baalrud
Recent findings suggest that ions are strongly correlated in atmospheric pressure plasmas if the ionization fraction is sufficiently high (≧10-5). A consequence is that ionization causes disorder-induced heating, which triggers a significant rise in ion temperature on a picosecond timescale. This is followed by a rise in the neutral gas temperature on a longer timescale of up to nanoseconds due to ion-neutral temperature relaxation. The sequence of disorder-induced heating and ion-neutral temperature relaxation suggests a new mechanism for ultrafast neutral gas heating. Previous work considered only the case of an instantaneous ionization pulse, whereas the ionization pulse extends over nanoseconds in many experiments. Here, molecular dynamics simulations are used to analyze the evolution of ion and neutral gas temperatures for a gradual ionization over several nanoseconds. The results are compared with published experimental results from a nanosecond pulsed discharge, showing good agreement with a measurement of fast neutral gas heating.
{"title":"Disorder-induced heating as a mechanism for fast neutral gas heating in atmospheric pressure plasmas","authors":"M. Acciarri, Chris Hudson Moore, Scott D Baalrud","doi":"10.1088/1361-6595/ad257e","DOIUrl":"https://doi.org/10.1088/1361-6595/ad257e","url":null,"abstract":"\u0000 Recent findings suggest that ions are strongly correlated in atmospheric pressure plasmas if the ionization fraction is sufficiently high (≧10-5). A consequence is that ionization causes disorder-induced heating, which triggers a significant rise in ion temperature on a picosecond timescale. This is followed by a rise in the neutral gas temperature on a longer timescale of up to nanoseconds due to ion-neutral temperature relaxation. The sequence of disorder-induced heating and ion-neutral temperature relaxation suggests a new mechanism for ultrafast neutral gas heating. Previous work considered only the case of an instantaneous ionization pulse, whereas the ionization pulse extends over nanoseconds in many experiments. Here, molecular dynamics simulations are used to analyze the evolution of ion and neutral gas temperatures for a gradual ionization over several nanoseconds. The results are compared with published experimental results from a nanosecond pulsed discharge, showing good agreement with a measurement of fast neutral gas heating.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"37 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139683639","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 : 2024-02-02DOI: 10.1088/1361-6595/ad257d
G. Arora, P. Hoffer, V. Prukner, Petr Bílek, Milan Šimek
The characteristics of nanosecond discharge propagating along the water-air interface in a unique DBD-like configuration with coplanar electrodes submerged in deionized/tap water are studied by combining ultrafast imaging and emission spectra with electrical characteristics. Time-resolved images provide a clear signature of diffusive plasma excited on the water surface at either side of the blade (insulated plastic separating the anode/cathode) called streamer phase and propagating perpendicularly away from it towards the anode /cathode with different velocities. Later on, the diffusive plasma converts into a few discrete and bright plasma filaments due to ionization instability (spark phase). There is no distinctive dependence in the streamer phase on water conductivity, but in the spark phase, more numerous, brighter, and thicker filaments form in tap water. The time-resolved emission spectra reveal the dominance of the first and second positive system of $mathrm{N_2}$ molecular bands in the streamer phase, followed by the appearance of atomic lines of hydrogen, nitrogen, and oxygen in the spark phase. The emission spectra are utilized to estimate plasma parameters (gas temperature ($T_d$), electric field ($E/N$), and electron density ($n_e$)) where a more dominant spark phase is formed in tap water with $T_dsim1100$ K, $E/N$ $sim800$ Td, and $n_esim10^{18}$ /$rm cm^{-3}$.
{"title":"Properties and characteristics of the nanosecond discharge developing at the water-air interface: tracking evolution from a diffused streamer to a spark filament","authors":"G. Arora, P. Hoffer, V. Prukner, Petr Bílek, Milan Šimek","doi":"10.1088/1361-6595/ad257d","DOIUrl":"https://doi.org/10.1088/1361-6595/ad257d","url":null,"abstract":"\u0000 The characteristics of nanosecond discharge propagating along the water-air interface in a unique DBD-like configuration with coplanar electrodes submerged in deionized/tap water are studied by combining ultrafast imaging and emission spectra with electrical characteristics. Time-resolved images provide a clear signature of diffusive plasma excited on the water surface at either side of the blade (insulated plastic separating the anode/cathode) called streamer phase and propagating perpendicularly away from it towards the anode /cathode with different velocities. Later on, the diffusive plasma converts into a few discrete and bright plasma filaments due to ionization instability (spark phase). There is no distinctive dependence in the streamer phase on water conductivity, but in the spark phase, more numerous, brighter, and thicker filaments form in tap water. The time-resolved emission spectra reveal the dominance of the first and second positive system of $mathrm{N_2}$ molecular bands in the streamer phase, followed by the appearance of atomic lines of hydrogen, nitrogen, and oxygen in the spark phase. The emission spectra are utilized to estimate plasma parameters (gas temperature ($T_d$), electric field ($E/N$), and electron density ($n_e$)) where a more dominant spark phase is formed in tap water with $T_dsim1100$ K, $E/N$ $sim800$ Td, and $n_esim10^{18}$ /$rm cm^{-3}$.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870256","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 : 2024-02-02DOI: 10.1088/1361-6595/ad2580
Leanid Simonchik, Mikalai Tomkavich, Gubad Islamov, E. Eylenceoglu, Ismail Rafatov
Combined experimental and numerical studies reveal a significant effect of the cathode temperature on the basic parameters (such as the electric field profile, thickness of the cathode fall layer, current density, and gas temperature) of the cathode fall of the self-sustained normal DC atmospheric pressure glow discharge (APGD) in helium. Numerical models are spatially one- and two-dimensional and based on drift-diffusion theory of gas discharges. It was observed that heating of the cathode, resulting from a flow of the discharge current in APGD with a constricted positive column, leads to an increase of the interelectrode voltage if the cathode is not cooled and its temperature increases. With additional heating of the cathode by an external heat source, the interelectrode voltage tends to decrease. Radially inhomogeneous profiles of the reduced electric field on the uncooled cathode surface were measured. Simulation results exhibit reasonably good agreement with experiment for APGDs with cooled and uncooled cathodes.
{"title":"Effect of the cathode surface temperature on the cathode fall layer parameters: experiment and simulation","authors":"Leanid Simonchik, Mikalai Tomkavich, Gubad Islamov, E. Eylenceoglu, Ismail Rafatov","doi":"10.1088/1361-6595/ad2580","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2580","url":null,"abstract":"\u0000 Combined experimental and numerical studies reveal a significant effect of the cathode temperature on the basic parameters (such as the electric field profile, thickness of the cathode fall layer, current density, and gas temperature) of the cathode fall of the self-sustained normal DC atmospheric pressure glow discharge (APGD) in helium. Numerical models are spatially one- and two-dimensional and based on drift-diffusion theory of gas discharges. It was observed that heating of the cathode, resulting from a flow of the discharge current in APGD with a constricted positive column, leads to an increase of the interelectrode voltage if the cathode is not cooled and its temperature increases. With additional heating of the cathode by an external heat source, the interelectrode voltage tends to decrease. Radially inhomogeneous profiles of the reduced electric field on the uncooled cathode surface were measured. Simulation results exhibit reasonably good agreement with experiment for APGDs with cooled and uncooled cathodes.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"9 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139683344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-08DOI: 10.1088/1361-6595/ad1c09
Petr Bílek, T. C. Dias, V. Prukner, V. Guerra, Milan Šimek
Vibrational distributions of electronically excited states of N2 obtained through dipole-allowed radiative transitions provide an important tool to study the kinetics of non-equilibrium plasmas under various discharge conditions. In this work, we report, for the first time, streamer-induced visible/near-infrared-red emission spectra developing during the first hundred nanoseconds after the initiation of the discharge. Emission through the first positive system of N2 was acquired in 500 - 1100 nm range, which allows a complete analysis of the N2(B3Πg, v=0-21) vibrational manifold. The investigated evolution of the vibrational distribution of the N2(B3Πg, v=0-21) state at the centre of the gap corresponds to the transition of the streamer head and the subsequent decay of the streamer channel. We show that the vibrational distribution characterising streamer head is determined by Franck-Condon factors, while during streamer relaxation, it is influenced by the complex interaction between triplet excited states of N2. Additionally, the observed N2(B3Πg, v=13-21) vibrational levels are likely produced by the interaction of high vibrational levels of N2(W3Δu, B’3Σu -, B3Πg) with N2(C3Πu) state. We also provide a detailed kinetic scheme for modelling vibrationally-resolved N2(B3Πg) state and compare model results with experimental outcomes.
{"title":"Streamer-induced kinetics of excited states in pure N2: II. Formation of N2(B3Πg, v=0-21) through analysis of emission produced by the first positive system","authors":"Petr Bílek, T. C. Dias, V. Prukner, V. Guerra, Milan Šimek","doi":"10.1088/1361-6595/ad1c09","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1c09","url":null,"abstract":"\u0000 Vibrational distributions of electronically excited states of N2 obtained through dipole-allowed radiative transitions provide an important tool to study the kinetics of non-equilibrium plasmas under various discharge conditions. In this work, we report, for the first time, streamer-induced visible/near-infrared-red emission spectra developing during the first hundred nanoseconds after the initiation of the discharge. Emission through the first positive system of N2 was acquired in 500 - 1100 nm range, which allows a complete analysis of the N2(B3Πg, v=0-21) vibrational manifold. The investigated evolution of the vibrational distribution of the N2(B3Πg, v=0-21) state at the centre of the gap corresponds to the transition of the streamer head and the subsequent decay of the streamer channel. We show that the vibrational distribution characterising streamer head is determined by Franck-Condon factors, while during streamer relaxation, it is influenced by the complex interaction between triplet excited states of N2. Additionally, the observed N2(B3Πg, v=13-21) vibrational levels are likely produced by the interaction of high vibrational levels of N2(W3Δu, B’3Σu\u0000 -, B3Πg) with N2(C3Πu) state. We also provide a detailed kinetic scheme for modelling vibrationally-resolved N2(B3Πg) state and compare model results with experimental outcomes.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"37 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139447989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-08DOI: 10.1088/1361-6595/ad1c08
Meng-Zhi Gu, Zhi-Cheng Lei, Yi-kang Pu
A two-region discharge model with a perturbation analysis was developed for the azimuthal striations observed in an inductively coupled plasma with an immersed cylindrical coil at pressures of 75–1500 mTorr. This model partitions the discharge area into two distinct regions: a bright region near the coil with intense excitation and ionization processes, and a darker region extending from the boundary of the bright core to the chamber wall. This partition reflects the experimental observation that striations are restricted to the vicinity of the coil and this phenomenon becomes more pronounced with increasing pressure. Through a perturbation analysis, the model indicates that the azimuthal striations manifest only below a critical power threshold, and this threshold decreases with pressure, which aligns with the experimental observations. Additionally, the model-predicted number of striations is in good agreement with the experiment over a wide pressure range.
{"title":"A two-region model for azimuthal striations in an inductively coupled plasma","authors":"Meng-Zhi Gu, Zhi-Cheng Lei, Yi-kang Pu","doi":"10.1088/1361-6595/ad1c08","DOIUrl":"https://doi.org/10.1088/1361-6595/ad1c08","url":null,"abstract":"\u0000 A two-region discharge model with a perturbation analysis was developed for the azimuthal striations observed in an inductively coupled plasma with an immersed cylindrical coil at pressures of 75–1500 mTorr. This model partitions the discharge area into two distinct regions: a bright region near the coil with intense excitation and ionization processes, and a darker region extending from the boundary of the bright core to the chamber wall. This partition reflects the experimental observation that striations are restricted to the vicinity of the coil and this phenomenon becomes more pronounced with increasing pressure. Through a perturbation analysis, the model indicates that the azimuthal striations manifest only below a critical power threshold, and this threshold decreases with pressure, which aligns with the experimental observations. Additionally, the model-predicted number of striations is in good agreement with the experiment over a wide pressure range.","PeriodicalId":508056,"journal":{"name":"Plasma Sources Science and Technology","volume":"9 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139445918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：