The electrical characteristics of the Gaseous Electronics Conference (GEC) reference cell at low pressures are investigated using a two-dimensional electrostatic implicit particle-in-cell / Monte Carlo collision model (PIC / MCC) in cylindrical coordinates. The coupling between the complex reactor geometry and the external circuit is included via an equivalent capacitance calculated from the electric energy density and the charge conservation equation. The results of this model are compared with experimental measurements and other model calculations and show agreement. The plasma series resonance (PSR) effect, closely related to electron heating, is observed in this numerical simulation of a strongly asymmetric reactor at low pressures. The plasma kinetics of the capacitively coupled discharge and details of the external circuit response, including electrical waveforms and higher-order harmonics, are discussed at different pressures, which provides important insights for understanding the power coupling mechanisms in capacitively coupled discharges.
{"title":"Electrical characteristics of the GEC reference cell at low pressure: A two-dimensional PIC/MCC modeling study","authors":"Zili Chen, Hongyu Wang, Shimin Yu, Yu Wang, Zhipeng Chen, Wei Jiang, Julian Schulze, Ya Zhang","doi":"10.1088/1361-6595/ad3849","DOIUrl":"https://doi.org/10.1088/1361-6595/ad3849","url":null,"abstract":"\u0000 The electrical characteristics of the Gaseous Electronics Conference (GEC) reference cell at low pressures are investigated using a two-dimensional electrostatic implicit particle-in-cell / Monte Carlo collision model (PIC / MCC) in cylindrical coordinates. The coupling between the complex reactor geometry and the external circuit is included via an equivalent capacitance calculated from the electric energy density and the charge conservation equation. The results of this model are compared with experimental measurements and other model calculations and show agreement. The plasma series resonance (PSR) effect, closely related to electron heating, is observed in this numerical simulation of a strongly asymmetric reactor at low pressures. The plasma kinetics of the capacitively coupled discharge and details of the external circuit response, including electrical waveforms and higher-order harmonics, are discussed at different pressures, which provides important insights for understanding the power coupling mechanisms in capacitively coupled discharges.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"27 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140375540","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 : 2024-03-26DOI: 10.1088/1361-6595/ad37bf
Yihao Guo, S. Nijdam
Streamers are fast-propagating ionization channels that can usually branch and form complex tree-like structures in dielectric media. In this paper, we perform experiments on positive streamers in different N2-O2 mixtures under varying conditions including voltage, pressure, and electrode geometry, with at least 125 discharge images captured for each condition. We present a statistical analysis on streamer branching characteristics from 3D models that are reconstructed by stereoscopic stroboscopic images and our dedicated semi-automatic 3D reconstruction method. We found that by varying the concentration of O2, the morphology and branching characteristics are greatly changed. Specifically, the average branching angle decrease significantly from 90° in air to 66° in 1% O2, suggesting that photoionization plays an important role in streamer branching. The branching angles in our work are generally larger than previously reported results due to the resolved 3D structures of discharges by our method. A linear relation between the streamer diameter ratio and the branching direction difference of two daughter branches is found, which intersects the vertical axis almost at unity. It is also found that the average branching angles, streamer velocities and diameters increase as the voltage increases. This is again attributed to stronger photoionization effect under higher voltages. The velocities and diameters are similar at different pressures but at the same reduced electric field. The average branching angle decreases from 90° at 133 mbar to 79° at 200 mbar. This suggests that stochastic fluctuations become dominant over photoionization effect at higher pressures.
{"title":"Statistical analysis on branching characteristics of positive streamer discharges in N2-O2 mixtures","authors":"Yihao Guo, S. Nijdam","doi":"10.1088/1361-6595/ad37bf","DOIUrl":"https://doi.org/10.1088/1361-6595/ad37bf","url":null,"abstract":"\u0000 Streamers are fast-propagating ionization channels that can usually branch and form complex tree-like structures in dielectric media. In this paper, we perform experiments on positive streamers in different N2-O2 mixtures under varying conditions including voltage, pressure, and electrode geometry, with at least 125 discharge images captured for each condition. We present a statistical analysis on streamer branching characteristics from 3D models that are reconstructed by stereoscopic stroboscopic images and our dedicated semi-automatic 3D reconstruction method. We found that by varying the concentration of O2, the morphology and branching characteristics are greatly changed. Specifically, the average branching angle decrease significantly from 90° in air to 66° in 1% O2, suggesting that photoionization plays an important role in streamer branching. The branching angles in our work are generally larger than previously reported results due to the resolved 3D structures of discharges by our method. A linear relation between the streamer diameter ratio and the branching direction difference of two daughter branches is found, which intersects the vertical axis almost at unity. It is also found that the average branching angles, streamer velocities and diameters increase as the voltage increases. This is again attributed to stronger photoionization effect under higher voltages. The velocities and diameters are similar at different pressures but at the same reduced electric field. The average branching angle decreases from 90° at 133 mbar to 79° at 200 mbar. This suggests that stochastic fluctuations become dominant over photoionization effect at higher pressures.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"65 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140378305","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 : 2024-03-25DOI: 10.1088/1361-6595/ad377a
Fresnelle Tenanguena Nongni, R. Kalus, M. Benhenni, F. Gadéa, Mohammed Yousfi
A general scheme for calculating ternary recombination rate constants of atomic species based on a hybrid quantum-classical nonadiabatic dynamics approach is presented and applied to a specific case of the ternary recombination of atomic ions of argon in cold argon plasmas. Rate constants are reported for both fine-structure states of the Ar$^+$ ion, $^2P_{3/2}$ and $^2P_{1/2}$, $T = 300$ K, and selected values of the reduced electric field. A thorough comparison with literature data available for $T=300$ K and a couple of close temperatures is performed with a favorable agreement achieved. It is shown that the excited Ar$^+(^2P_{1/2})$ ions may contribute to the formation of dimer ions, Ar$_2^+$, as efficiently as the ground-state ions, Ar$^+(^2P_{3/2})$, due to fast internal conversion of the electronic energy which takes place in ternary collision complexes, Ar$^+$/Ar/Ar.
{"title":"Formation of Ar2\u0000 + ions in cold argon plasmas through the ternary recombination mechanism","authors":"Fresnelle Tenanguena Nongni, R. Kalus, M. Benhenni, F. Gadéa, Mohammed Yousfi","doi":"10.1088/1361-6595/ad377a","DOIUrl":"https://doi.org/10.1088/1361-6595/ad377a","url":null,"abstract":"\u0000 A general scheme for calculating ternary recombination rate constants of atomic species based on a hybrid quantum-classical nonadiabatic dynamics approach is presented and applied to a specific case of the ternary recombination of atomic ions of argon in cold argon plasmas. Rate constants are reported for both fine-structure states of the Ar$^+$ ion, $^2P_{3/2}$ and $^2P_{1/2}$, $T = 300$ K, and selected values of the reduced electric field. A thorough comparison with literature data available for $T=300$ K and a couple of close temperatures is performed with a favorable agreement achieved. It is shown that the excited Ar$^+(^2P_{1/2})$ ions may contribute to the formation of dimer ions, Ar$_2^+$, as efficiently as the ground-state ions, Ar$^+(^2P_{3/2})$, due to fast internal conversion of the electronic energy which takes place in ternary collision complexes, Ar$^+$/Ar/Ar.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":" 980","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140382325","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 : 2024-03-20DOI: 10.1088/1361-6595/ad31b3
Mai Hao, Boya Zhang, Xingwen Li, Peiqiong Liu, Yuyang Yao, Anthony B Murphy
In this work, a convenient and efficient method is proposed to determine swarm parameters considering ion kinetics from pulsed Townsend (PT) measurements. First, a physical model was presented to describe the development of PT discharge considering electron detachment and ion conversion reactions. A numerical solution to the model was also proposed. In order to assess the precision of our calculations, we presented the calculated electronic and ionic transients derived from our model for different cases. Then, a genetic algorithm (GA) was proposed to find a set of swarm parameters, under which the deviation between the simulated current waveform and the actual measured current waveform is minimum. It is time-consuming to simulate a single waveform, and since a large number of waveforms need to be simulated in the GA, graphic processing unit-based parallel computing is used to improve computing efficiency. Finally, the swarm parameters of dry air considering electron detachment and ion conversion processes using the method were obtained and they are in good agreement with those in references.
在这项工作中，我们提出了一种便捷高效的方法，通过脉冲汤森（PT）测量来确定考虑到离子动力学的蜂群参数。首先，考虑到电子脱离和离子转换反应，提出了一个物理模型来描述 PT 放电的发展过程。此外，还提出了该模型的数值解决方案。为了评估计算的精确性，我们展示了根据模型计算出的不同情况下的电子和离子瞬态。然后，我们提出了一种遗传算法（GA）来寻找一组蜂群参数，在该参数下，模拟电流波形与实际测量电流波形之间的偏差最小。模拟单个波形耗时较长，由于在 GA 中需要模拟大量波形，因此采用了基于图形处理单元的并行计算来提高计算效率。最后，利用该方法得到了考虑了电子脱离和离子转换过程的干燥空气的蜂群参数，这些参数与参考文献中的参数非常一致。
{"title":"Determining the swarm parameters of gases considering ion kinetics by parallel genetic algorithm on GPU platform","authors":"Mai Hao, Boya Zhang, Xingwen Li, Peiqiong Liu, Yuyang Yao, Anthony B Murphy","doi":"10.1088/1361-6595/ad31b3","DOIUrl":"https://doi.org/10.1088/1361-6595/ad31b3","url":null,"abstract":"In this work, a convenient and efficient method is proposed to determine swarm parameters considering ion kinetics from pulsed Townsend (PT) measurements. First, a physical model was presented to describe the development of PT discharge considering electron detachment and ion conversion reactions. A numerical solution to the model was also proposed. In order to assess the precision of our calculations, we presented the calculated electronic and ionic transients derived from our model for different cases. Then, a genetic algorithm (GA) was proposed to find a set of swarm parameters, under which the deviation between the simulated current waveform and the actual measured current waveform is minimum. It is time-consuming to simulate a single waveform, and since a large number of waveforms need to be simulated in the GA, graphic processing unit-based parallel computing is used to improve computing efficiency. Finally, the swarm parameters of dry air considering electron detachment and ion conversion processes using the method were obtained and they are in good agreement with those in references.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313804","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 : 2024-03-18DOI: 10.1088/1361-6595/ad2d6c
Jiao Zhang, Weiwei Tang, Yanhui Wang, Dezhen Wang
In this study, a two-dimensional fluid model is employed to simulate the streamer, pressure wave, and vortex in surface dielectric barrier discharge driven by nanosecond pulse voltage (ns-SDBD). It comprises a numerical model with two interconnected modules: discharge dynamics and gas flow dynamics. These modules are coupled through the physical variables including ‘EHD force’, ‘thermal source’, ‘velocity field’, ‘gas temperature’, and ‘gas pressure’. Our research primarily focuses on the underlying physical mechanisms of pressure waves and vortices for plasma-based flow control. The generation of pressure waves is attributed to the rapid gas heating by pulsed discharge, whereas the formation and development of the vortex are related to the ionic wind (EHD effect) provided by the plasma. To thoroughly understand and optimize flow control performance, an investigation into the effects of various discharge parameters, such as voltage amplitude and polarity, is conducted. Additionally, several SDBD modules are arranged in series, each featuring a dual three-electrode configuration. Subsequently, the dynamic behaviors of multiple streamers, pressure waves, and vortices, along with their interactions, are explored.
{"title":"Numerical simulation of streamer, pressure wave, and vortex induced by nanosecond pulsed surface dielectric barrier discharges","authors":"Jiao Zhang, Weiwei Tang, Yanhui Wang, Dezhen Wang","doi":"10.1088/1361-6595/ad2d6c","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2d6c","url":null,"abstract":"In this study, a two-dimensional fluid model is employed to simulate the streamer, pressure wave, and vortex in surface dielectric barrier discharge driven by nanosecond pulse voltage (ns-SDBD). It comprises a numerical model with two interconnected modules: discharge dynamics and gas flow dynamics. These modules are coupled through the physical variables including ‘EHD force’, ‘thermal source’, ‘velocity field’, ‘gas temperature’, and ‘gas pressure’. Our research primarily focuses on the underlying physical mechanisms of pressure waves and vortices for plasma-based flow control. The generation of pressure waves is attributed to the rapid gas heating by pulsed discharge, whereas the formation and development of the vortex are related to the ionic wind (EHD effect) provided by the plasma. To thoroughly understand and optimize flow control performance, an investigation into the effects of various discharge parameters, such as voltage amplitude and polarity, is conducted. Additionally, several SDBD modules are arranged in series, each featuring a dual three-electrode configuration. Subsequently, the dynamic behaviors of multiple streamers, pressure waves, and vortices, along with their interactions, are explored.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313874","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 : 2024-03-11DOI: 10.1088/1361-6595/ad29be
Abhishek Verma, Shahid Rauf, Kallol Bera, D Sydorenko, A Khrabrov, Igor Kaganovich
Low-pressure multi-frequency capacitively coupled plasmas (CCPs) are used for numerous etch and deposition applications in the semiconductor industry. Pulsing of the radio-frequency (RF) sources enables control of neutral and charged species in the plasma on a millisecond timescale. The synchronous (i.e. simultaneous, in-phase) pulsing of both power sources in a dual frequency CCP is examined in this article. Due to the low gas pressure, modeling has been done using the electrostatic particle-in-cell/Monte Carlo collision method. The objective of this work is to investigate the sensitivity of the plasma properties to small changes in timing during synchronous pulsing of the two RF sources. It is demonstrated that small deviations in the on and off times of the two RF sources can lead to major changes in the plasma characteristics. This high sensitivity is of concern for process repeatability but can be utilized to enable better control of the dynamics of plasma-surface interaction. In the simulations, the pulsing parameters (on and off times and ramp rates) are varied and the temporal evolution of plasma characteristics such as electron density (ne), species current at the electrode, and electron temperature are examined. It is demonstrated that if the low-frequency (LF) source is turned off a few μs before (or after) the high-frequency source, ne during the off-state is significantly higher (or lower) due to the frequency coupling effect. Similarly, turning on the LF source with a small delay results in a sharp increase in the plasma density when the RF sources are turned on.
{"title":"Study of synchronous RF pulsing in dual frequency capacitively coupled plasma","authors":"Abhishek Verma, Shahid Rauf, Kallol Bera, D Sydorenko, A Khrabrov, Igor Kaganovich","doi":"10.1088/1361-6595/ad29be","DOIUrl":"https://doi.org/10.1088/1361-6595/ad29be","url":null,"abstract":"Low-pressure multi-frequency capacitively coupled plasmas (CCPs) are used for numerous etch and deposition applications in the semiconductor industry. Pulsing of the radio-frequency (RF) sources enables control of neutral and charged species in the plasma on a millisecond timescale. The synchronous (i.e. simultaneous, in-phase) pulsing of both power sources in a dual frequency CCP is examined in this article. Due to the low gas pressure, modeling has been done using the electrostatic particle-in-cell/Monte Carlo collision method. The objective of this work is to investigate the sensitivity of the plasma properties to small changes in timing during synchronous pulsing of the two RF sources. It is demonstrated that small deviations in the on and off times of the two RF sources can lead to major changes in the plasma characteristics. This high sensitivity is of concern for process repeatability but can be utilized to enable better control of the dynamics of plasma-surface interaction. In the simulations, the pulsing parameters (on and off times and ramp rates) are varied and the temporal evolution of plasma characteristics such as electron density (<italic toggle=\"yes\">n<sub>e</sub>\u0000</italic>), species current at the electrode, and electron temperature are examined. It is demonstrated that if the low-frequency (LF) source is turned off a few <italic toggle=\"yes\">μ</italic>s before (or after) the high-frequency source, <italic toggle=\"yes\">n<sub>e</sub>\u0000</italic> during the off-state is significantly higher (or lower) due to the frequency coupling effect. Similarly, turning on the LF source with a small delay results in a sharp increase in the plasma density when the RF sources are turned on.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313857","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}
Electric field measurements based on the electric field induced second harmonic (E-FISH) method have been employed in a wide range of studies. Most studies typically measure two components of the electric field separately. Although there have been proposals for the simultaneous measurement of electric field vectors, the imbalance of the two corresponding E-FISH signals has limited its application. Furthermore, the relationship between the polarization of the E-FISH signal and the direction of external electric field remains unclear. In this paper, the general expressions for the polarization and power of both components of E-FISH signals are derived, assuming arbitrary probe beam polarization and external electric field direction. The theoretical results indicate that the polarization of E-FISH signals varies along the interaction length. The final signal’s polarization is elliptically polarized for arbitrary electric field distribution and is correlated with the polarization of the probe beam, which deviates from what is commonly assumed to be consistent with the external electric field. If the polarization of the probe beam is not parallel to the axes, the power of each signal component is determined by both components of the external electric field, which lays the foundation for the simultaneous measurement of electric field vectors. This theoretical prediction is subsequently validated by experimental results. Finally, the power maps suggest that the optimal polarization angle of the probe beam is 45° or 135° to achieve a balanced signal power when measuring an unknown electric field vector. Both components of the electric field can be simultaneously obtained according to the theoretical relationship.
{"title":"Polarization properties of E-FISH signals and optimization of simultaneous measurement of electric field vectors","authors":"Xinlei Zheng, Zheng Zhao, Haotian Zheng, Zongze Huang, Zihan Sun, Jiangtao Li","doi":"10.1088/1361-6595/ad2e3c","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2e3c","url":null,"abstract":"Electric field measurements based on the electric field induced second harmonic (E-FISH) method have been employed in a wide range of studies. Most studies typically measure two components of the electric field separately. Although there have been proposals for the simultaneous measurement of electric field vectors, the imbalance of the two corresponding E-FISH signals has limited its application. Furthermore, the relationship between the polarization of the E-FISH signal and the direction of external electric field remains unclear. In this paper, the general expressions for the polarization and power of both components of E-FISH signals are derived, assuming arbitrary probe beam polarization and external electric field direction. The theoretical results indicate that the polarization of E-FISH signals varies along the interaction length. The final signal’s polarization is elliptically polarized for arbitrary electric field distribution and is correlated with the polarization of the probe beam, which deviates from what is commonly assumed to be consistent with the external electric field. If the polarization of the probe beam is not parallel to the axes, the power of each signal component is determined by both components of the external electric field, which lays the foundation for the simultaneous measurement of electric field vectors. This theoretical prediction is subsequently validated by experimental results. Finally, the power maps suggest that the optimal polarization angle of the probe beam is 45° or 135° to achieve a balanced signal power when measuring an unknown electric field vector. Both components of the electric field can be simultaneously obtained according to the theoretical relationship.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"180 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313819","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 : 2024-03-06DOI: 10.1088/1361-6595/ad2c9a
Dingyuan Peng, Jialu Duan, Lan Li, Ruobing Zhang
Porous discharge has been widely studied recent years, however the discharge development inside the pores with complicated structure was little involved. In this paper, the discharge developments in vertical and tortuous pore are studied using a 2D fluid model in Cartesian coordinate system established by COMSOL Multiphysics. The discharge develops symmetrically and bilaterally in vertical pore, and along the higher potential sidewall in tortuous pore, respectively. For tortuous pore, there are two pre-ionization process with negative and positive polarity successively, the latter one splits off from the former one and is in the form of multiple ionizing heads propagating simultaneously in string. The negative one can induce the primary discharge to deflect at the channel elbow joint in a ‘splitting-quenching’ way or directly deflect it by bridging with it. For the positive one, the multiple ionizing heads can distort the electric field and short cut the potential and thus accelerate the primary discharge. Furthermore, the discharge can be enhanced deep inside the tortuous pore by the large number of seed electrons provided by pre-ionization. The influence of the dielectric constant is also studied, with the dielectric constant increases, the discharge can maintain bilateral morphology in tortuous pores for a deeper development distance.
{"title":"Micro-discharge in tortuous pores: ‘splitting-quenching’ of primary ionization wave and the role of pre-ionization","authors":"Dingyuan Peng, Jialu Duan, Lan Li, Ruobing Zhang","doi":"10.1088/1361-6595/ad2c9a","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2c9a","url":null,"abstract":"Porous discharge has been widely studied recent years, however the discharge development inside the pores with complicated structure was little involved. In this paper, the discharge developments in vertical and tortuous pore are studied using a 2D fluid model in Cartesian coordinate system established by COMSOL Multiphysics. The discharge develops symmetrically and bilaterally in vertical pore, and along the higher potential sidewall in tortuous pore, respectively. For tortuous pore, there are two pre-ionization process with negative and positive polarity successively, the latter one splits off from the former one and is in the form of multiple ionizing heads propagating simultaneously in string. The negative one can induce the primary discharge to deflect at the channel elbow joint in a ‘splitting-quenching’ way or directly deflect it by bridging with it. For the positive one, the multiple ionizing heads can distort the electric field and short cut the potential and thus accelerate the primary discharge. Furthermore, the discharge can be enhanced deep inside the tortuous pore by the large number of seed electrons provided by pre-ionization. The influence of the dielectric constant is also studied, with the dielectric constant increases, the discharge can maintain bilateral morphology in tortuous pores for a deeper development distance.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"234 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316746","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 : 2024-03-04DOI: 10.1088/1361-6595/ad2b7c
Junhwi Bak, Albina Tropina, James Creel, Richard B Miles
In this work, the potential for hypersonic leading edge cooling by electron emission is demonstrated. To overcome space charge limitations the experiments are carried out in an argon discharge at 1 Torr. Cooling is observed with time-resolved measurements of the electron emission current and surface temperature, taking advantage of well controlled laser heating of the emitting surface and time accurate surface pyrometry. For the ignited mode of the plasma discharge, surface cooling by the electron emission is directly observed, leading to an estimated cooling rate of 1.6±0.2 MW m−2. Higher cooling rates with self sustained plasmas for space charge mitigation are expected using cesium transpiration. A two-dimensional model of heat transfer has been developed, which reproduces well the experimentally observed cooling dynamics. Parametric tests of emitter materials with various work functions show that for effective surface cooling by electron emission, the optimal work function must be less than 3.0 eV. This result indicates that electron cooling can be a promising thermal protection method for leading edges of hypersonic vehicles in flight.
{"title":"Quantification of plasma enabled surface cooling by electron emission from high temperature materials","authors":"Junhwi Bak, Albina Tropina, James Creel, Richard B Miles","doi":"10.1088/1361-6595/ad2b7c","DOIUrl":"https://doi.org/10.1088/1361-6595/ad2b7c","url":null,"abstract":"In this work, the potential for hypersonic leading edge cooling by electron emission is demonstrated. To overcome space charge limitations the experiments are carried out in an argon discharge at 1 Torr. Cooling is observed with time-resolved measurements of the electron emission current and surface temperature, taking advantage of well controlled laser heating of the emitting surface and time accurate surface pyrometry. For the ignited mode of the plasma discharge, surface cooling by the electron emission is directly observed, leading to an estimated cooling rate of <inline-formula>\u0000<tex-math><?CDATA $1.6pm0.2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>1.6</mml:mn><mml:mo>±</mml:mo><mml:mn>0.2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"psstad2b7cieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> MW m<sup>−2</sup>. Higher cooling rates with self sustained plasmas for space charge mitigation are expected using cesium transpiration. A two-dimensional model of heat transfer has been developed, which reproduces well the experimentally observed cooling dynamics. Parametric tests of emitter materials with various work functions show that for effective surface cooling by electron emission, the optimal work function must be less than 3.0 eV. This result indicates that electron cooling can be a promising thermal protection method for leading edges of hypersonic vehicles in flight.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"68 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140313817","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: 10.1088/1361-6595/ad29c0
R Marskar
Sprite discharges are electrical discharges that initiate from the lower ionosphere during intense lightning storms, manifesting themselves optically as flashes of light that last a few milliseconds. This study unravels sprite initiation mechanisms and evolution into distinctive morphologies like glows and beads, using direct 3D numerical simulations that capture the intricate electrical discharge processes. We clarify various morphological aspects of sprites such as the halo dynamics, column glows, branching, streamer reconnection, and bead formation. The results advance our understanding of sprites and their connection to thunderstorm dynamics, and puts quantitative analysis of their effect on Earth’s climate within reach.
{"title":"Genesis of column sprites: formation mechanisms and optical structures","authors":"R Marskar","doi":"10.1088/1361-6595/ad29c0","DOIUrl":"https://doi.org/10.1088/1361-6595/ad29c0","url":null,"abstract":"Sprite discharges are electrical discharges that initiate from the lower ionosphere during intense lightning storms, manifesting themselves optically as flashes of light that last a few milliseconds. This study unravels sprite initiation mechanisms and evolution into distinctive morphologies like glows and beads, using direct 3D numerical simulations that capture the intricate electrical discharge processes. We clarify various morphological aspects of sprites such as the halo dynamics, column glows, branching, streamer reconnection, and bead formation. The results advance our understanding of sprites and their connection to thunderstorm dynamics, and puts quantitative analysis of their effect on Earth’s climate within reach.","PeriodicalId":20192,"journal":{"name":"Plasma Sources Science and Technology","volume":"128 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002139","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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