Pub Date : 2022-03-01DOI: 10.1088/2516-1067/ac61c2
S. Iséni
This is a Reply to the Comment of Dozias S., Pouvesle J.-M. and Robert E. on the paper ‘Mapping the electric field vector of guided ionization waves at atmospheric pressure’. The criticism in the Comment, namely that the measurements and the subsequent interpretations are wrong, seems to be invalid. Additional information will be detailed to discuss the point of view of the authors. However, the criticism raises an interesting comparison of two data sets presented in a normalized color scale. The resulting figure clearly supports the argument that the plasma-induced electric field measurements are consistent and validates the experimental investigation.
{"title":"Reply to ‘Commentary on Mapping the electric field vector of guided ionization waves at atmospheric pressure, (2020) Plasma Res. Express 2 025014)’","authors":"S. Iséni","doi":"10.1088/2516-1067/ac61c2","DOIUrl":"https://doi.org/10.1088/2516-1067/ac61c2","url":null,"abstract":"This is a Reply to the Comment of Dozias S., Pouvesle J.-M. and Robert E. on the paper ‘Mapping the electric field vector of guided ionization waves at atmospheric pressure’. The criticism in the Comment, namely that the measurements and the subsequent interpretations are wrong, seems to be invalid. Additional information will be detailed to discuss the point of view of the authors. However, the criticism raises an interesting comparison of two data sets presented in a normalized color scale. The resulting figure clearly supports the argument that the plasma-induced electric field measurements are consistent and validates the experimental investigation.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48500960","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 : 2022-01-28DOI: 10.1088/2516-1067/ac4bea
M. Alam, M. Talukder
The characteristic behaviour of breathers as well as N-order Rogue wave (RW) solution in homogeneous unmagnetized electron-positron-ion plasmas (consisting of cold ions, and isothermal Maxwellian electrons and positrons) has been studied theoretically. Nonlinear Schrödinger (NLS) equation is derived employing Krylov-Bogoliubov-Mitropolosky (KBM) perturbation technique in solving the concerned problems. The analytical solution of the NLS equation in the forms of breathers such as Akhmediev breather (AB), Kuznetsov-Ma breather (KM) solitons, as well as first-, second-, third-, and fourth-order RWs solution are obtained. The characteristic behaviour of breathers’ and their dependency on the relevant physical parameters are examined. The different orders of RWs are analyzed to obtain the region of existence of ion acoustic (IA) rogue waves (IARWs) with respect to unstable region. The potential profiles concerning different orders of RWs depend on the ratio of positron to electron concentrations ( ρ ) and wave number ( k ). Analysis reveals that the spatial difference between the two adjacent peaks of AB profiles are increasing with the enhancement of transformer physical parameter ( Λ ), while the temporal evolution between the two neighboring peaks of KM profiles decreases with increasing Λ and the amplitudes become large as well. The amplitudes of first-, second-, and third-order RWs profiles are decreasing with increasing ρ while the amplitude of fourth-order RWs profile is increasing. The results obtained in this study may be useful in understanding the propagation of nonlinear waves in optical fibers, Bose-Einstein condensates, plasma physics and atmospheric physics.
{"title":"Characteristic behaviour of N-order ion acoustic rogue waves solution in electron-positron-ion plasmas","authors":"M. Alam, M. Talukder","doi":"10.1088/2516-1067/ac4bea","DOIUrl":"https://doi.org/10.1088/2516-1067/ac4bea","url":null,"abstract":"The characteristic behaviour of breathers as well as N-order Rogue wave (RW) solution in homogeneous unmagnetized electron-positron-ion plasmas (consisting of cold ions, and isothermal Maxwellian electrons and positrons) has been studied theoretically. Nonlinear Schrödinger (NLS) equation is derived employing Krylov-Bogoliubov-Mitropolosky (KBM) perturbation technique in solving the concerned problems. The analytical solution of the NLS equation in the forms of breathers such as Akhmediev breather (AB), Kuznetsov-Ma breather (KM) solitons, as well as first-, second-, third-, and fourth-order RWs solution are obtained. The characteristic behaviour of breathers’ and their dependency on the relevant physical parameters are examined. The different orders of RWs are analyzed to obtain the region of existence of ion acoustic (IA) rogue waves (IARWs) with respect to unstable region. The potential profiles concerning different orders of RWs depend on the ratio of positron to electron concentrations ( ρ ) and wave number ( k ). Analysis reveals that the spatial difference between the two adjacent peaks of AB profiles are increasing with the enhancement of transformer physical parameter ( Λ ), while the temporal evolution between the two neighboring peaks of KM profiles decreases with increasing Λ and the amplitudes become large as well. The amplitudes of first-, second-, and third-order RWs profiles are decreasing with increasing ρ while the amplitude of fourth-order RWs profile is increasing. The results obtained in this study may be useful in understanding the propagation of nonlinear waves in optical fibers, Bose-Einstein condensates, plasma physics and atmospheric physics.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47941140","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 : 2022-01-26DOI: 10.1088/2516-1067/ac4f35
F. J. Gonzalez, J. I. Gonzalez, S. Soler, C. Repetto, B. J. Gómez, D. Berdichevsky
We describe a procedure to obtain the plasma parameters from the I-V Langmuir curve by using the Druyvesteyn equation. We propose to include two new parameters, q and r, to the usual plasma parameters: plasma potential (V p ), floating potential (V f ), electron density (n), and electron temperature (T). These new parameters can be particularly useful to represent non-Maxwellian distributions. The procedure is based on the fit of the I-V Langmuir curve with the q-Weibull distribution function, and is motivated by recent works which use the q-exponential distribution function derived from Tsallis statistics. We obtain the usual plasma parameters employing three techniques: the numerical differentiation using Savitzky Golay (SG) filters, the q-exponential distribution function, and the q-Weibull distribution function. We explain the limitations of the q-exponential function, where the experimental data V > V p needs to be trimmed beforehand, and this results in a lower accuracy compared to the numerical differentiation with SG. To overcome this difficulty, the q-Weibull function is introduced as a natural generalization to the q-exponential distribution, and it has greater flexibility in order to represent the concavity change around V p . We apply this procedure to analyze the measurements corresponding to a nitrogen N 2 cold plasma obtained by using a single Langmuir probe located at different heights from the cathode. We show that the q parameter has a very stable numerical value with the height. This work may contribute to clarify some advantages and limitations of the use of non-extensive statistics in plasma diagnostics, but the physical interpretation of the non-extensive parameters in plasma physics remains not fully clarified, and requires further research.
{"title":"New procedure to estimate plasma parameters through the q-Weibull distribution by using a Langmuir probe in a cold plasma","authors":"F. J. Gonzalez, J. I. Gonzalez, S. Soler, C. Repetto, B. J. Gómez, D. Berdichevsky","doi":"10.1088/2516-1067/ac4f35","DOIUrl":"https://doi.org/10.1088/2516-1067/ac4f35","url":null,"abstract":"We describe a procedure to obtain the plasma parameters from the I-V Langmuir curve by using the Druyvesteyn equation. We propose to include two new parameters, q and r, to the usual plasma parameters: plasma potential (V p ), floating potential (V f ), electron density (n), and electron temperature (T). These new parameters can be particularly useful to represent non-Maxwellian distributions. The procedure is based on the fit of the I-V Langmuir curve with the q-Weibull distribution function, and is motivated by recent works which use the q-exponential distribution function derived from Tsallis statistics. We obtain the usual plasma parameters employing three techniques: the numerical differentiation using Savitzky Golay (SG) filters, the q-exponential distribution function, and the q-Weibull distribution function. We explain the limitations of the q-exponential function, where the experimental data V > V p needs to be trimmed beforehand, and this results in a lower accuracy compared to the numerical differentiation with SG. To overcome this difficulty, the q-Weibull function is introduced as a natural generalization to the q-exponential distribution, and it has greater flexibility in order to represent the concavity change around V p . We apply this procedure to analyze the measurements corresponding to a nitrogen N 2 cold plasma obtained by using a single Langmuir probe located at different heights from the cathode. We show that the q parameter has a very stable numerical value with the height. This work may contribute to clarify some advantages and limitations of the use of non-extensive statistics in plasma diagnostics, but the physical interpretation of the non-extensive parameters in plasma physics remains not fully clarified, and requires further research.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44427538","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 : 2022-01-20DOI: 10.1088/2516-1067/ac4d87
N. Behera, R. K. Singh, G. Prakash, K. Patel, H. Joshi, Ajai Kumar
Time-varying diamagnetism in laser-produced plasma moving across a transverse magnetic field for different field strengths has been studied using fast imaging and magnetic probe. The emphasis of the present work is on the development of suitable B-dot probe, quantitative analysis of induced diamagnetic field in an expanding plasma plume and its effect on the applied magnetic field profiles. A Helmholtz coil with pulsed power system is used to produce uniform magnetic field varying from 0.13 T to 0.57 T. Helmholtz coil allows the plume imaging along the magnetic field lines, which gives the direct structural information of the induced diamagnetic cavity. A high frequency three-axis B-dot probe has been developed to measure the transient magnetic field. Different experimental approaches have been used to test the response, sensitivity and calibration of the developed probe. It has been observed that induced magnetic field displaced the external magnetic field that is plasma plume shows the diamagnetic behaviour for considered magnetic field range. The probe signals in directions orthogonal to the applied/induced magnetic lines are correlated with the distortion in applied magnetic field in three dimensional space, which is consistent with recently simulated topology of external magnetic field in similar experimental conditions [Patel et al, 2021 Plasma Phys. Control. Fusion 63 115020 ].
利用快速成像和磁探针研究了激光等离子体在不同场强下在横向磁场中运动时的抗磁性。本文的工作重点是研制合适的b点探针，定量分析膨胀等离子体羽流中诱导抗磁场及其对外加磁场剖面的影响。采用脉冲功率系统的亥姆霍兹线圈产生0.13 ~ 0.57 T的均匀磁场，利用亥姆霍兹线圈沿磁力线进行羽流成像，得到感应抗磁腔的直接结构信息。研制了一种用于瞬态磁场测量的高频三轴b点探头。采用不同的实验方法来测试所开发探针的响应、灵敏度和校准。在考虑的磁场范围内，等离子体羽流表现出抗磁性。与外加磁力线/感应磁力线正交方向的探针信号与外加磁场在三维空间中的畸变相关，这与最近在类似实验条件下模拟的外磁场拓扑一致[Patel et al .， 2021 Plasma physics]。控制。聚变[63[15020]。
{"title":"B-dot probe measurements on plasma plume expansion across the magnetic field","authors":"N. Behera, R. K. Singh, G. Prakash, K. Patel, H. Joshi, Ajai Kumar","doi":"10.1088/2516-1067/ac4d87","DOIUrl":"https://doi.org/10.1088/2516-1067/ac4d87","url":null,"abstract":"Time-varying diamagnetism in laser-produced plasma moving across a transverse magnetic field for different field strengths has been studied using fast imaging and magnetic probe. The emphasis of the present work is on the development of suitable B-dot probe, quantitative analysis of induced diamagnetic field in an expanding plasma plume and its effect on the applied magnetic field profiles. A Helmholtz coil with pulsed power system is used to produce uniform magnetic field varying from 0.13 T to 0.57 T. Helmholtz coil allows the plume imaging along the magnetic field lines, which gives the direct structural information of the induced diamagnetic cavity. A high frequency three-axis B-dot probe has been developed to measure the transient magnetic field. Different experimental approaches have been used to test the response, sensitivity and calibration of the developed probe. It has been observed that induced magnetic field displaced the external magnetic field that is plasma plume shows the diamagnetic behaviour for considered magnetic field range. The probe signals in directions orthogonal to the applied/induced magnetic lines are correlated with the distortion in applied magnetic field in three dimensional space, which is consistent with recently simulated topology of external magnetic field in similar experimental conditions [Patel et al, 2021 Plasma Phys. Control. Fusion 63 115020 ].","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42558003","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 : 2022-01-01DOI: 10.1088/2516-1067/ac728a
Shachi Pachauri, Jyoti, K. Misra
An analytical formalism to understand the impact of various parameters on evolving instabilities in inhomogeneous collisional dusty plasmas is presented here under the effect of recombination. The basic fluid dynamics for electrons and singly charged cold ions is carried out including recombination and collision at constant rate at the surface of dust particles. Dust particles are considered to be static with unperturbed density. Normal mode analysis method has been used along with linear approximation to get perturbed densities (n i1, n e1) which are used along with quasi-neutrality condition to get perturbed potential (φ1), using Poisson’s equation to obtain dispersion relation. While other authors have detected instabilities in unmagnetized plasmas, here this method has been successfully realized in presence of static magnetic field at various propagation angle and allowed the straightforward calculation of growth rates of observed instability. An extensive study of the unstable modes has been done which are well discriminated and plotted with respect to different plasma parameters like dust charge, dust density, propagation angle, magnetic field, electrostatic potential along with plasma oscillation wavelength to Debye wavelength ratio. We have observed in the said model that the presence of dust particles and propagation angle of applied magnetic field are affecting significantly the growth rate of instability as compared to magnetic field and recombination.
{"title":"Instabilities in magnetized inhomogeneous dusty plasmas with the effect of recombination","authors":"Shachi Pachauri, Jyoti, K. Misra","doi":"10.1088/2516-1067/ac728a","DOIUrl":"https://doi.org/10.1088/2516-1067/ac728a","url":null,"abstract":"An analytical formalism to understand the impact of various parameters on evolving instabilities in inhomogeneous collisional dusty plasmas is presented here under the effect of recombination. The basic fluid dynamics for electrons and singly charged cold ions is carried out including recombination and collision at constant rate at the surface of dust particles. Dust particles are considered to be static with unperturbed density. Normal mode analysis method has been used along with linear approximation to get perturbed densities (n i1, n e1) which are used along with quasi-neutrality condition to get perturbed potential (φ1), using Poisson’s equation to obtain dispersion relation. While other authors have detected instabilities in unmagnetized plasmas, here this method has been successfully realized in presence of static magnetic field at various propagation angle and allowed the straightforward calculation of growth rates of observed instability. An extensive study of the unstable modes has been done which are well discriminated and plotted with respect to different plasma parameters like dust charge, dust density, propagation angle, magnetic field, electrostatic potential along with plasma oscillation wavelength to Debye wavelength ratio. We have observed in the said model that the presence of dust particles and propagation angle of applied magnetic field are affecting significantly the growth rate of instability as compared to magnetic field and recombination.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":"135 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61181769","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 : 2021-12-02DOI: 10.1088/2516-1067/ac3fa3
M. Yadav, Ajay Kumar, Subhayan Mandal
Laser irradiated parallel gold nanorods with interspersed deuterium nanoparticles are shown to offer guided acceleration of nanoparticles. The laser pulse of intensity exceeding 1018 W cm−2 at 1 μm wavelength and pulse duration ∼30 fs causes full ionization of nanoparticles and high state ionization of gold atoms and pushes out the free electrons via the ponderomotive force. The charged nanorods have an electric field that has transverse component towards the axis of symmetry and axial field outwards. Thus the nanoparticles are accelerated axially while confined transversely. Deuterium beam of a few MeV energy can be produced by this technique.
用激光照射平行金纳米棒并点缀氘纳米颗粒，可以提供纳米颗粒的引导加速。波长为1 μm、脉冲持续时间为~ 30 fs、强度超过1018 W cm−2的激光脉冲使纳米粒子完全电离，金原子高态电离，并通过质动势将自由电子推出。带电纳米棒具有一个电场，该电场具有向对称轴方向的横向分量和向外的轴向分量。因此，纳米粒子被轴向加速，而被横向限制。利用该技术可以产生几兆电子伏能量的氘束。
{"title":"Guided acceleration of nanoparticles by laser irradiated parallel gold nanorods","authors":"M. Yadav, Ajay Kumar, Subhayan Mandal","doi":"10.1088/2516-1067/ac3fa3","DOIUrl":"https://doi.org/10.1088/2516-1067/ac3fa3","url":null,"abstract":"Laser irradiated parallel gold nanorods with interspersed deuterium nanoparticles are shown to offer guided acceleration of nanoparticles. The laser pulse of intensity exceeding 1018 W cm−2 at 1 μm wavelength and pulse duration ∼30 fs causes full ionization of nanoparticles and high state ionization of gold atoms and pushes out the free electrons via the ponderomotive force. The charged nanorods have an electric field that has transverse component towards the axis of symmetry and axial field outwards. Thus the nanoparticles are accelerated axially while confined transversely. Deuterium beam of a few MeV energy can be produced by this technique.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43944718","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 : 2021-11-23DOI: 10.1088/2516-1067/ac3c4d
P. Sahu
The proliferation of the cylindrical shock in non-ideal rotating gases accompanying the mixture of crystalline solids with monochromatic radiation as well as magnetic (azimuthal/axial) field is examined. The fluid velocity of ambient media is considered to contain radial, axial, and azimuthal heads. Similarity solutions are achieved. The distribution of flow variables in the medium just behind the shock for the cases of power-law shock paths are analyzed. This is worthy to note, the pressure and density at piston disintegrate in occupancy of an azimuthal magnetic field, therefore suction structures at the axis of symmetry, which is identically in accord with controlled circumstances for trying to produce shock waves.
{"title":"Flow behind the magnetogasdynamical cylindrical shock wave in rotating non-ideal dusty gas with monochromatic radiation","authors":"P. Sahu","doi":"10.1088/2516-1067/ac3c4d","DOIUrl":"https://doi.org/10.1088/2516-1067/ac3c4d","url":null,"abstract":"The proliferation of the cylindrical shock in non-ideal rotating gases accompanying the mixture of crystalline solids with monochromatic radiation as well as magnetic (azimuthal/axial) field is examined. The fluid velocity of ambient media is considered to contain radial, axial, and azimuthal heads. Similarity solutions are achieved. The distribution of flow variables in the medium just behind the shock for the cases of power-law shock paths are analyzed. This is worthy to note, the pressure and density at piston disintegrate in occupancy of an azimuthal magnetic field, therefore suction structures at the axis of symmetry, which is identically in accord with controlled circumstances for trying to produce shock waves.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43093229","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 : 2021-11-03DOI: 10.1088/2516-1067/ac3628
S. Kondrashev, E. Beebe, T. Kanesue, M. Okamura, R. Scott
Picosecond lasers (ps-lasers) have significant advantages for the generation of low charge state ions compared to nanosecond lasers because the influence of heat conductivity on a solid target is almost negligible in the case of ps-laser ablation for laser pulse durations less than 10 ps. However, there is no comprehensive data on ion yields for different elements and target irradiation conditions for laser power densities at the target surface around and below 1013 W cm−2, which is of interest to our study of such plasmas as a source of low charge state ions for various applications, particularly for external injection of those ions into an Electron Beam Ion Source (EBIS). We investigated ion generation from Al, Ti, Cu, Nb and Ta target elements by a ps-laser with power densities in the range of 1011–1013 W cm−2 at the target surface. A ps-laser with 1.27 mJ maximum energy within an 8 ps pulse and repetition rate up to 400 Hz has been used to generate a laser-ablated plasma. Dependencies of ion current versus time, total charge of registered ions as well as ion kinetic energy distributions are characterized using a Faraday cup. Significant difference in ion current dynamics between first, second and following shots onto the same target spot was found for all five target elements. The total charge of ions registered by the Faraday cup increases linearly with increasing laser pulse energy and is almost independent of the target element and number of shots onto the same target spot for all five target elements studied. The results obtained give us a basis for specification and design of the source of low charge state ions for external injection into EBIS.
与纳秒激光器相比，皮秒激光器(ps激光器)在产生低电荷态离子方面具有显著优势，因为在激光脉冲持续时间小于10 ps的情况下，皮秒激光烧蚀对固体目标的导热性影响几乎可以忽略不计。然而，在目标表面约1013 W cm−2及以下的激光功率密度下，没有关于不同元素和目标照射条件下离子产量的综合数据。这对我们研究等离子体作为各种应用的低电荷态离子源，特别是将这些离子外部注入电子束离子源(EBIS)很有兴趣。利用功率密度在1011-1013 W cm−2范围内的ps激光器，研究了Al, Ti, Cu, Nb和Ta靶元素在靶表面的离子生成。在8ps脉冲和高达400hz的重复频率下，使用最大能量为1.27 mJ的ps激光器产生激光烧蚀等离子体。利用法拉第杯表征了离子电流与时间的关系、注册离子的总电荷以及离子动能分布。对于所有五种目标元素，在同一目标点上的第一次，第二次和后续射击之间的离子电流动力学存在显着差异。法拉第杯记录的离子总电荷随激光脉冲能量的增加而线性增加，并且几乎与所研究的五种靶元素的靶元素和射向同一靶点的次数无关。所得结果为外注入EBIS的低电荷态离子源的规格和设计提供了依据。
{"title":"Features of ion generation by a picosecond laser in the range of 1011–1013 W cm−2 power densities","authors":"S. Kondrashev, E. Beebe, T. Kanesue, M. Okamura, R. Scott","doi":"10.1088/2516-1067/ac3628","DOIUrl":"https://doi.org/10.1088/2516-1067/ac3628","url":null,"abstract":"Picosecond lasers (ps-lasers) have significant advantages for the generation of low charge state ions compared to nanosecond lasers because the influence of heat conductivity on a solid target is almost negligible in the case of ps-laser ablation for laser pulse durations less than 10 ps. However, there is no comprehensive data on ion yields for different elements and target irradiation conditions for laser power densities at the target surface around and below 1013 W cm−2, which is of interest to our study of such plasmas as a source of low charge state ions for various applications, particularly for external injection of those ions into an Electron Beam Ion Source (EBIS). We investigated ion generation from Al, Ti, Cu, Nb and Ta target elements by a ps-laser with power densities in the range of 1011–1013 W cm−2 at the target surface. A ps-laser with 1.27 mJ maximum energy within an 8 ps pulse and repetition rate up to 400 Hz has been used to generate a laser-ablated plasma. Dependencies of ion current versus time, total charge of registered ions as well as ion kinetic energy distributions are characterized using a Faraday cup. Significant difference in ion current dynamics between first, second and following shots onto the same target spot was found for all five target elements. The total charge of ions registered by the Faraday cup increases linearly with increasing laser pulse energy and is almost independent of the target element and number of shots onto the same target spot for all five target elements studied. The results obtained give us a basis for specification and design of the source of low charge state ions for external injection into EBIS.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43713295","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 : 2021-10-15DOI: 10.1088/2516-1067/ac3018
L. Babich, I. Kutsyk, E. Bochkov, C. Köhn, T. Neubert
Local section of one streamer in the streamer coronas ahead of negative leaders of long laboratory sparks can develop into ‘space leaders’, called so because of their high conductivity and initially being unconnected to the main negative leader. Available data of experimental research do not allow reliably unveiling a mechanism causal to the space leader birth. We, here, discuss a hypothetical but general mechanism based, mostly, on thermodynamics. The plasma-chemistry processes in one of the streamers of the negative leader corona and Joule heating of the gas within the streamer channel are casual to a birth of a conducting area in this streamer at the strength of the ambient electric field less than the selfbreakdown magnitude of 30 kV cm−1. Two conclusions follow from the analysis. First, sufficiently high ambient field strength E 0 is required to heat the gas to a temperature sufficiently high for a birth of the conducting area during the observed time t obs. Second, the current of one streamer does provide sufficient heating; for this, the being heated area is to be fed by a multitude of the streamer branches. We limit ourselves to considering processes responsible for a formation of hot conducting areas in the negative corona. We assume that the birth of the heated area in the streamer, start new streamers from its ends and further heating of this area occurs in some local domain where the field strength exceeds the mean magnitude 11 kV cm−1 in the leader corona. We, proceeding from the experimentally observed time t obs of 1 μs, show that the minimal magnitude of the E 0 of 20 kV cm−1 in the being heated area is required to ensure the gas temperature of 2000 K fitting the t obs. To illustrate our conclusions, we, using simplified models, carry out simulations treating selfconsistently the evolution of the electric field and the associated plasma chemistry.
{"title":"General processes responsible for the space leader birth in streamer coronas of negative leaders","authors":"L. Babich, I. Kutsyk, E. Bochkov, C. Köhn, T. Neubert","doi":"10.1088/2516-1067/ac3018","DOIUrl":"https://doi.org/10.1088/2516-1067/ac3018","url":null,"abstract":"Local section of one streamer in the streamer coronas ahead of negative leaders of long laboratory sparks can develop into ‘space leaders’, called so because of their high conductivity and initially being unconnected to the main negative leader. Available data of experimental research do not allow reliably unveiling a mechanism causal to the space leader birth. We, here, discuss a hypothetical but general mechanism based, mostly, on thermodynamics. The plasma-chemistry processes in one of the streamers of the negative leader corona and Joule heating of the gas within the streamer channel are casual to a birth of a conducting area in this streamer at the strength of the ambient electric field less than the selfbreakdown magnitude of 30 kV cm−1. Two conclusions follow from the analysis. First, sufficiently high ambient field strength E 0 is required to heat the gas to a temperature sufficiently high for a birth of the conducting area during the observed time t obs. Second, the current of one streamer does provide sufficient heating; for this, the being heated area is to be fed by a multitude of the streamer branches. We limit ourselves to considering processes responsible for a formation of hot conducting areas in the negative corona. We assume that the birth of the heated area in the streamer, start new streamers from its ends and further heating of this area occurs in some local domain where the field strength exceeds the mean magnitude 11 kV cm−1 in the leader corona. We, proceeding from the experimentally observed time t obs of 1 μs, show that the minimal magnitude of the E 0 of 20 kV cm−1 in the being heated area is required to ensure the gas temperature of 2000 K fitting the t obs. To illustrate our conclusions, we, using simplified models, carry out simulations treating selfconsistently the evolution of the electric field and the associated plasma chemistry.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45766701","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 : 2021-09-01DOI: 10.1088/2516-1067/ac256a
K. McClements, J. Young, L. Garzotti, OM Jones, C. Michael
A set of soft x-ray cameras provided measurements of high frequency instabilities as well as steady-state emission in the Mega Amp Spherical Tokamak (MAST). It is shown that Abel inversion can be readily applied to fluctuating soft x-ray emission from the MAST midplane associated with fast particle-driven ‘fishbone’ instabilities, characterised by toroidal mode number n = 1. Each fishbone burst had an early phase in which high amplitude fluctuating soft x-ray signals from the plasma core were close to being in phase with each other, and there was a region close to the outboard plasma edge in which the fluctuations were relatively weak and in antiphase with those in the core. The major radius of the ‘phase axis’ at which the mode amplitude changed sign R p was initially outboard of the tokamak magnetic axis at R 0, but moved inboard during the burst, eventually becoming close to R 0, at which time the oscillations were of similar amplitude inboard and outboard of R p . The fishbone radial structure early in the burst can be understood in part by recognising that the mode is supported by energetic ions with a high average toroidal rotation rate: in a co-rotating frame, the effective magnetic axis is shifted outboard by a distance that is comparable to the difference between the major radii of the phase axis early in the burst and the laboratory frame magnetic axis. It is conjectured that the transition to a mode with R p ≃ R 0 occurred because most of the energetic ions were expelled from the plasma core region where the mode amplitude peaked, so that the instability could no longer be characterised as an energetic particle mode. Abel inversion of fishbone soft x-ray emission thus provides useful insights into the nature of energetic particle modes in tokamak plasmas and their relationship with MHD modes.
{"title":"Abel inversion of soft x-ray fluctuations associated with fast particle-driven fishbone instabilities in MAST plasmas","authors":"K. McClements, J. Young, L. Garzotti, OM Jones, C. Michael","doi":"10.1088/2516-1067/ac256a","DOIUrl":"https://doi.org/10.1088/2516-1067/ac256a","url":null,"abstract":"A set of soft x-ray cameras provided measurements of high frequency instabilities as well as steady-state emission in the Mega Amp Spherical Tokamak (MAST). It is shown that Abel inversion can be readily applied to fluctuating soft x-ray emission from the MAST midplane associated with fast particle-driven ‘fishbone’ instabilities, characterised by toroidal mode number n = 1. Each fishbone burst had an early phase in which high amplitude fluctuating soft x-ray signals from the plasma core were close to being in phase with each other, and there was a region close to the outboard plasma edge in which the fluctuations were relatively weak and in antiphase with those in the core. The major radius of the ‘phase axis’ at which the mode amplitude changed sign R p was initially outboard of the tokamak magnetic axis at R 0, but moved inboard during the burst, eventually becoming close to R 0, at which time the oscillations were of similar amplitude inboard and outboard of R p . The fishbone radial structure early in the burst can be understood in part by recognising that the mode is supported by energetic ions with a high average toroidal rotation rate: in a co-rotating frame, the effective magnetic axis is shifted outboard by a distance that is comparable to the difference between the major radii of the phase axis early in the burst and the laboratory frame magnetic axis. It is conjectured that the transition to a mode with R p ≃ R 0 occurred because most of the energetic ions were expelled from the plasma core region where the mode amplitude peaked, so that the instability could no longer be characterised as an energetic particle mode. Abel inversion of fishbone soft x-ray emission thus provides useful insights into the nature of energetic particle modes in tokamak plasmas and their relationship with MHD modes.","PeriodicalId":36295,"journal":{"name":"Plasma Research Express","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43349164","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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