Langevin molecular dynamics simulations reveal the impact of confinement strength on the structure and dynamics of a two-dimensional complex plasma under constant shear force.Structural analysis via Voronoi diagrams a...Langevin molecular dynamics simulations reveal the impact of confinement strength on the structure and dynamics of a two-dimensional complex plasma under constant shear force.Structural analysis via Voronoi diagrams and the local bond-order parameter|Ψ6|shows that stronger confinement enhances hexagonal order and mitigates shear-induced disorder.Dynamical properties,determined by mean-square displacement(MSD)and the velocity autocorrelation function(VACF),indicate that the shear-induced superdiffusion weakens with increasing confinement strength.The entropy change(?S)shows that strong confinement(ω>1)balances particle dynamics between shear and shear-free regions,thereby stabilizing the system.These findings highlight the interplay between confinement and shear force.展开更多
The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient...The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient obtained from HNEMD is dependent on various plasma parameters （T,k）. The proposed algorithm gives accurate results with fast convergence and small size effect over a wide range of plasma parameters. The cross microscopic heat energy current is discussed in association with variation of temperature （1/Г） and external perturbations （Pz）. The thermal conductivity obtained from HNEMD simulations is found to be very good agreement and more reliable than previously known numerical techniques of equilibrium molecular dynarnic, nonequilibrium molecular dynamic simulations. Our new investigations point to an effective conclusion that the thermal conductivity of complex dusty plasmas is dependent on an extensive range of plasma coupling （P） and screening parameter （k） and it varies by the alteration in these parameters. It is also shown that a different approach is used for computations of thermal conductivity in 2D complex plasmas and can be appropriate method for behaviors of complex systems.展开更多
Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-de...Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.展开更多
Dust-acoustic waves(DAWs)are analyzed in the small amplitude limit in a collisionless unmagnetized dusty plasma whose constituents are inertial dust grains,massless ions expressed by the generalized(r,q)distribution a...Dust-acoustic waves(DAWs)are analyzed in the small amplitude limit in a collisionless unmagnetized dusty plasma whose constituents are inertial dust grains,massless ions expressed by the generalized(r,q)distribution and inertialess Maxwellian electrons using the fluid theory of plasmas.The modified Kadomtsev-Petviashvili(mKP)equation is derived at a critical plasma condition for which the quadratic nonlinearity vanishes.The propagation of single soliton and interaction of two solitons are analyzed for the mKP equation in the context of plasma physics by employing Hirota bilinear formalism.The effects of the flatness parameter rand tail parameter q of the ions on the frequency of the DAWs are studied and the comparison with Maxwellian and kappa distributions is drawn.Using the plasma parameters corresponding to the Saturn’s E-ring,the range of electric field amplitude for dust-acoustic solitary waves(DASWs)for different ion distributions is calculated and is shown to agree very well with the Cassini Wideband Receiver(WBR)observations.The interaction time of two DASWs for non-Maxwellian ion distributions is estimated and shown to be fastest for the(r,q)distributed ions.The interesting feature of the interaction between compressive solitons with their rarefactive counterparts is also discussed in detail.展开更多
For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is...For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is found that md/mi,nd/ne0 and Q/e contribute to the coupling strength of the system,and Te/Ti contributes to the shielding cloud surrounding the charged dust particles.Further analysis shows that the modified Yukawa potential depends on Te/Ti.The consequent structure changes of the system are discussed based on the Langevin dynamics simulation.It is found that the variation of Ham-iltonian contributes to the equilibrium structure of the system.展开更多
We employ the Green–Kubo(G-K)and Einstein relations to estimate the self-diffusion coefficients(denoted as D_(G)and D_(E),respectively)in two-dimensional(2D)strongly coupled dusty plasmas(SC-DPs)via equilibrium molec...We employ the Green–Kubo(G-K)and Einstein relations to estimate the self-diffusion coefficients(denoted as D_(G)and D_(E),respectively)in two-dimensional(2D)strongly coupled dusty plasmas(SC-DPs)via equilibrium molecular dynamics(EMD)simulations.D_(G)and D_(E)are computed for a broad domain of screening length(κ)and coupling parameters(Γ)along with different system sizes.It is observed that both D_(G)and D_(E)decrease linearly with increasing Г in warm liquid states and increase with increasingκ.In cold liquid states,the Einstein relation accurately predicts D_(E)in 2D SC-DPs because diffusion motion is close to normal diffusion,but the G-K relation provides overestimations of D_(G),because VACF indicates anomalous diffusion;thus,D_(G)is not accurate.Our new simulation outcomes reveal that D_(G)and D_(E)remain independent of system sizes.Furthermore,our investigations demonstrate that at higher temperatures,D_(G)and D_(E)converge,suggesting diffusion motion close to normal diffusion,while at lower temperatures,these two values diverge.We find reasonable agreement by comparing current and existing numerical,theoretical and experimental data.Moreover,when normalizing diffusion coefficients by the Einstein frequency and testing against the universal temperature scaling law,D_(G)deviates from theoretical curves at low temperatures and κ,whereas D_(E)only disagrees with theory at very smallκ(■0.10).These findings provide valuable insight into diagnosing dust component parameters within 2D DP systems and contribute to the broader understanding of diffusion processes in DP environments.展开更多
Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of part...Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of particles,as well as the discharge glow,strongly depend on discharge parameters.However,traditional manual diagnosis methods for recognizing discharge parameters from discharge images are complicated to operate with low accuracy,time-consuming and high requirement of instruments.To solve these problems,by combining the two mechanisms of attention mechanism(strengthening the extraction of the channel feature)and shortcut connection(enabling the input information to be directly transmitted to deep networks and avoiding the disappearance or explosion of gradients),the network of squeeze and excitation convolution with shortcut(SECS)for complex plasma image recognition is proposed to effectively improve the model performance.The results show that the accuracy,precision,recall and F1-Score of our model are superior to other models in complex plasma image recognition,and the recognition accuracy reaches 97.38%.Moreover,the recognition accuracy for the Flowers and Chest X-ray publicly available data sets reaches 97.85%and 98.65%,respectively,and our model has robustness.This study shows that the proposed model provides a new method for the diagnosis of complex plasma images and also provides technical support for the application of plasma in industrial production.展开更多
Cylindrical and spherical dust-electron-acoustic （DEA） shock waves and double layers in an unmagnetized, col- lisionless, complex or dusty plasma system are carried out. The plasma system is assumed to be composed o...Cylindrical and spherical dust-electron-acoustic （DEA） shock waves and double layers in an unmagnetized, col- lisionless, complex or dusty plasma system are carried out. The plasma system is assumed to be composed of inertial and viscous cold electron fluids, nonextensive distributed hot electrons, Maxwellian ions, and negatively charged stationary dust grains. The standard reductive perturbation technique is used to derive the nonlinear dynamical equations, that is, the nonplanar Burgers equation and the nonplanar further Burgers equation. They are also numerically analyzed to investigate the basic features of shock waves and double layers （DLs）. It is observed that the roles of the viscous cold electron fluids, nonextensivity of hot electrons, and other plasma parameters in this investigation have significantly modified the basic features （such as, polarity, amplitude and width） of the nonplanar DEA shock waves and DLs. It is also observed that the strength of the shock is maximal for the spherical geometry, intermediate for cylindrical geometry, while it is minimal for the planar geometry. The findings of our results obtained from this theoretical investigation may be useful in understanding the nonlinear phenomena associated with the nonplanar DEA waves in both space and laboratory plasmas.展开更多
Our interest is to study the nonlinear wave phenomena in complex plasma constituents with Maxwellian electrons and ions. The main aim is to use a new method known as the(G′/G)method to exhibit the effects of dust cha...Our interest is to study the nonlinear wave phenomena in complex plasma constituents with Maxwellian electrons and ions. The main aim is to use a new method known as the(G′/G)method to exhibit the effects of dust charge fluctuations on the evolution of nonlinear waves. The coherent features of the shock and solitary waves along with the generation of high-energy waves have been amplified through the solution of the Korteweg–de Vries–Burgers equation,and the different natures of the waves were found successfully. Results are discussed graphically with the thoughtful choice of typical plasma parameters from different space plasma environments, exactly those found in cosmic dusty plasmas laden in ionospheric auroral region,radial spokes of Saturn's rings, planetary nebulae and solar F-corona region. All conclusions are in good accordance with the actual occurrences and could be of interest to further investigations of space. Moreover, the applicability of the present method is hoped to be a great enhancement by its use as ingenious mechanism used to evaluate the soliton dynamics and Burgers shock waves.展开更多
Complex plasma fluctuation processes have been extensively studied in many aspects,especially lattice waves in strongly coupled plasma crystals,which are of great significance for understanding fundamental physical ph...Complex plasma fluctuation processes have been extensively studied in many aspects,especially lattice waves in strongly coupled plasma crystals,which are of great significance for understanding fundamental physical phenomena.A challenge of experimental investigations in two-dimensional strongly coupled complex plasma crystals is to keep the main body and foreign particles of different masses on the same horizontal plane.To solve the problem,we have proposed a potential well formed by two negatively biased grids to bind the negatively charged particles in a two-dimensional(2D)plane,thus achieving a 2D plasma crystal in the microgravity environment.The study of such phenomena in complex plasma crystals under microgravity environment then becomes possible.In this paper,we focus on the continuum spectrum,including both phonon and optic branches of the impurity mode in a 2D system in microgravity environments.The results show the dispersion relation of the longitudinal and transverse impurity oscillation modes and their properties.Considering the macroscopic visibility of complex mesoscopic particle lattices,theoretical and experimental studies on this kind of complex plasma systems will help us further understand the physical nature of a wide range of condensed matters.展开更多
We focus on molecular dynamics simulated two-dimensional complex plasma crystals. We use rigid walls as a confinement force and produce square and rectangular crystals. We report various types of two-row crystals. The...We focus on molecular dynamics simulated two-dimensional complex plasma crystals. We use rigid walls as a confinement force and produce square and rectangular crystals. We report various types of two-row crystals. The narrow and long crystals are likely to be used as wigglers; therefore, we simulate such crystals. Also, we analyze the electric fields of simulated crystals. A bit change in lattice parameters can change the internal structures of crystals and their electric fields notably. These parameters are the number of grains, grains charge, length, and width of the crystal. With the help of electric fields, we show the details of crystal structures.展开更多
In this paper we have developed a model to study the role of both electron and ion nonthermalities on dust acoustic wave propagation in a complex plasma in presence of positively charged dust grains. Secondary electro...In this paper we have developed a model to study the role of both electron and ion nonthermalities on dust acoustic wave propagation in a complex plasma in presence of positively charged dust grains. Secondary electron emission from dust grains has been considered as the source of positive dust charging. As secondary emission current depends on the flux of primary electrons, nonthermality of primary electrons changes the expression of secondary emission current from that of earlier work where primary electrons were thermal. Expression of nonthermal electron current flowing to the positively charged dust grains and consequently the expression of secondary electron current flowing out of the dust grains have been first time calculated in this paper, whereas the expression for nonthermal ion current flowing to the positively charged dust grains is present in existing literature. Dispersion relation of dust acoustic wave has been derived. From this dispersion relation real frequency and growth rate of the wave have been calculated. Results have been plotted for different strength of nonthermalities of electrons and ions.展开更多
A rigorous theoretical investigation of linear dust ion acoustic (DIA) solitary waves in an unmagnetized complex plasma consisting of ion and ion beam fluids, nonthermal electrons that are Cairns distributed and immob...A rigorous theoretical investigation of linear dust ion acoustic (DIA) solitary waves in an unmagnetized complex plasma consisting of ion and ion beam fluids, nonthermal electrons that are Cairns distributed and immobile dust particles were undertaken. It was found out that, for large beam speeds, three stable modes propagated as solitary waves in the beam plasma. These were the “Fast”, “Slow” and “Ion-acoustic” modes. For two stream instability to occur between ion and ion beam, it is shown that or when .展开更多
The effects of thermionic emission on dust-acoustic solitons with a very small but finite amplitude in a dustelectron plasma are studied using the reductive perturbation technique. The self-consistent variation of dus...The effects of thermionic emission on dust-acoustic solitons with a very small but finite amplitude in a dustelectron plasma are studied using the reductive perturbation technique. The self-consistent variation of dust charge is taken into account. It is shown that the thermionic emission could significantly increase the dust positive charge. The dependences of the phase velocity, amplitude, and width of such solitons on the dust temperature and the dust work function of dust material are plotted and discussed.展开更多
Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical defin...Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical definition of the ratio of the internal pressure/stress to the volume strain. Under various conditions, the bulk moduli obtained agree with the previous theoretical derivations from completely different approaches. It is found that the bulk moduli of2D Yukawa solids and liquids are almost independent of the system temperature and the external compressional frequency.展开更多
The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characteriz...The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.展开更多
The process of complex granules prepared by HF plasma spraying through axial feeding and thermodynamic analysis of the process is described. The densification factors of complex granules is also discussed, the result ...The process of complex granules prepared by HF plasma spraying through axial feeding and thermodynamic analysis of the process is described. The densification factors of complex granules is also discussed, the result of which coincides with the test results. The process has the advantages of simple processing, convenient operation, high purity and wide applications. It is an effective way for producing complex granules by multicomponent metallic powders and ceramic metal powders.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12075315)。
文摘Langevin molecular dynamics simulations reveal the impact of confinement strength on the structure and dynamics of a two-dimensional complex plasma under constant shear force.Structural analysis via Voronoi diagrams and the local bond-order parameter|Ψ6|shows that stronger confinement enhances hexagonal order and mitigates shear-induced disorder.Dynamical properties,determined by mean-square displacement(MSD)and the velocity autocorrelation function(VACF),indicate that the shear-induced superdiffusion weakens with increasing confinement strength.The entropy change(?S)shows that strong confinement(ω>1)balances particle dynamics between shear and shear-free regions,thereby stabilizing the system.These findings highlight the interplay between confinement and shear force.
文摘The thermal conductivity of complex fluid materials （dusty plasmas） has been explored through novel Evan-Gillan homogeneous non-equilibrium molecular dynamic （HNEMD） algorithm. The thermal conductivity coefficient obtained from HNEMD is dependent on various plasma parameters （T,k）. The proposed algorithm gives accurate results with fast convergence and small size effect over a wide range of plasma parameters. The cross microscopic heat energy current is discussed in association with variation of temperature （1/Г） and external perturbations （Pz）. The thermal conductivity obtained from HNEMD simulations is found to be very good agreement and more reliable than previously known numerical techniques of equilibrium molecular dynarnic, nonequilibrium molecular dynamic simulations. Our new investigations point to an effective conclusion that the thermal conductivity of complex dusty plasmas is dependent on an extensive range of plasma coupling （P） and screening parameter （k） and it varies by the alteration in these parameters. It is also shown that a different approach is used for computations of thermal conductivity in 2D complex plasmas and can be appropriate method for behaviors of complex systems.
基金funding from Grant No. HIDSS-0002 DASHH (Data Science in Hamburg-Helmholtz Graduate School for the Structure of Matter)partially supported by the Helmholtz Imaging platform through the project “Smart Phase.”
文摘Understanding the complex plasma dynamics in ultra-intense relativistic laser-solid interactions is of fundamental importance for applications of laser-plasma-based particle accelerators,the creation of high-energy-density matter,understanding planetary science,and laser-driven fusion energy.However,experimental efforts in this regime have been limited by the lack of accessibility of over-critical densities and the poor spatiotemporal resolution of conventional diagnostics.Over the last decade,the advent of femtosecond brilliant hard X-ray free-electron lasers(XFELs)has opened new horizons to overcome these limitations.Here,for the first time,we present full-scale spatiotemporal measurements of solid-density plasma dynamics,including preplasma generation with tens of nanometer scale length driven by the leading edge of a relativistic laser pulse,ultrafast heating and ionization at the main pulse arrival,the laser-driven blast wave,and transient surface return current-induced compression dynamics up to hundreds of picoseconds after interaction.These observations are enabled by utilizing a novel combination of advanced X-ray diagnostics including small-angle X-ray scattering,resonant X-ray emission spectroscopy,and propagation-based X-ray phase-contrast imaging simultaneously at the European XFEL-HED beamline station.
文摘Dust-acoustic waves(DAWs)are analyzed in the small amplitude limit in a collisionless unmagnetized dusty plasma whose constituents are inertial dust grains,massless ions expressed by the generalized(r,q)distribution and inertialess Maxwellian electrons using the fluid theory of plasmas.The modified Kadomtsev-Petviashvili(mKP)equation is derived at a critical plasma condition for which the quadratic nonlinearity vanishes.The propagation of single soliton and interaction of two solitons are analyzed for the mKP equation in the context of plasma physics by employing Hirota bilinear formalism.The effects of the flatness parameter rand tail parameter q of the ions on the frequency of the DAWs are studied and the comparison with Maxwellian and kappa distributions is drawn.Using the plasma parameters corresponding to the Saturn’s E-ring,the range of electric field amplitude for dust-acoustic solitary waves(DASWs)for different ion distributions is calculated and is shown to agree very well with the Cassini Wideband Receiver(WBR)observations.The interaction time of two DASWs for non-Maxwellian ion distributions is estimated and shown to be fastest for the(r,q)distributed ions.The interesting feature of the interaction between compressive solitons with their rarefactive counterparts is also discussed in detail.
基金Supported by National Natural Science Foundation of China(12275354,11805272)the College Students'Innovative Entrepreneurial Training Plan Program of Civil Aviation University of China(202210059080)。
文摘For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is found that md/mi,nd/ne0 and Q/e contribute to the coupling strength of the system,and Te/Ti contributes to the shielding cloud surrounding the charged dust particles.Further analysis shows that the modified Yukawa potential depends on Te/Ti.The consequent structure changes of the system are discussed based on the Langevin dynamics simulation.It is found that the variation of Ham-iltonian contributes to the equilibrium structure of the system.
基金support of the Fundamental Research Funds for the Central Universities of China(Grant No.2019ZDPY16).
文摘We employ the Green–Kubo(G-K)and Einstein relations to estimate the self-diffusion coefficients(denoted as D_(G)and D_(E),respectively)in two-dimensional(2D)strongly coupled dusty plasmas(SC-DPs)via equilibrium molecular dynamics(EMD)simulations.D_(G)and D_(E)are computed for a broad domain of screening length(κ)and coupling parameters(Γ)along with different system sizes.It is observed that both D_(G)and D_(E)decrease linearly with increasing Г in warm liquid states and increase with increasingκ.In cold liquid states,the Einstein relation accurately predicts D_(E)in 2D SC-DPs because diffusion motion is close to normal diffusion,but the G-K relation provides overestimations of D_(G),because VACF indicates anomalous diffusion;thus,D_(G)is not accurate.Our new simulation outcomes reveal that D_(G)and D_(E)remain independent of system sizes.Furthermore,our investigations demonstrate that at higher temperatures,D_(G)and D_(E)converge,suggesting diffusion motion close to normal diffusion,while at lower temperatures,these two values diverge.We find reasonable agreement by comparing current and existing numerical,theoretical and experimental data.Moreover,when normalizing diffusion coefficients by the Einstein frequency and testing against the universal temperature scaling law,D_(G)deviates from theoretical curves at low temperatures and κ,whereas D_(E)only disagrees with theory at very smallκ(■0.10).These findings provide valuable insight into diagnosing dust component parameters within 2D DP systems and contribute to the broader understanding of diffusion processes in DP environments.
基金This study was supported by a grand from the National Natural Science Foundation of China(No.12075315).
文摘Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of particles,as well as the discharge glow,strongly depend on discharge parameters.However,traditional manual diagnosis methods for recognizing discharge parameters from discharge images are complicated to operate with low accuracy,time-consuming and high requirement of instruments.To solve these problems,by combining the two mechanisms of attention mechanism(strengthening the extraction of the channel feature)and shortcut connection(enabling the input information to be directly transmitted to deep networks and avoiding the disappearance or explosion of gradients),the network of squeeze and excitation convolution with shortcut(SECS)for complex plasma image recognition is proposed to effectively improve the model performance.The results show that the accuracy,precision,recall and F1-Score of our model are superior to other models in complex plasma image recognition,and the recognition accuracy reaches 97.38%.Moreover,the recognition accuracy for the Flowers and Chest X-ray publicly available data sets reaches 97.85%and 98.65%,respectively,and our model has robustness.This study shows that the proposed model provides a new method for the diagnosis of complex plasma images and also provides technical support for the application of plasma in industrial production.
文摘Cylindrical and spherical dust-electron-acoustic （DEA） shock waves and double layers in an unmagnetized, col- lisionless, complex or dusty plasma system are carried out. The plasma system is assumed to be composed of inertial and viscous cold electron fluids, nonextensive distributed hot electrons, Maxwellian ions, and negatively charged stationary dust grains. The standard reductive perturbation technique is used to derive the nonlinear dynamical equations, that is, the nonplanar Burgers equation and the nonplanar further Burgers equation. They are also numerically analyzed to investigate the basic features of shock waves and double layers （DLs）. It is observed that the roles of the viscous cold electron fluids, nonextensivity of hot electrons, and other plasma parameters in this investigation have significantly modified the basic features （such as, polarity, amplitude and width） of the nonplanar DEA shock waves and DLs. It is also observed that the strength of the shock is maximal for the spherical geometry, intermediate for cylindrical geometry, while it is minimal for the planar geometry. The findings of our results obtained from this theoretical investigation may be useful in understanding the nonlinear phenomena associated with the nonplanar DEA waves in both space and laboratory plasmas.
文摘Our interest is to study the nonlinear wave phenomena in complex plasma constituents with Maxwellian electrons and ions. The main aim is to use a new method known as the(G′/G)method to exhibit the effects of dust charge fluctuations on the evolution of nonlinear waves. The coherent features of the shock and solitary waves along with the generation of high-energy waves have been amplified through the solution of the Korteweg–de Vries–Burgers equation,and the different natures of the waves were found successfully. Results are discussed graphically with the thoughtful choice of typical plasma parameters from different space plasma environments, exactly those found in cosmic dusty plasmas laden in ionospheric auroral region,radial spokes of Saturn's rings, planetary nebulae and solar F-corona region. All conclusions are in good accordance with the actual occurrences and could be of interest to further investigations of space. Moreover, the applicability of the present method is hoped to be a great enhancement by its use as ingenious mechanism used to evaluate the soliton dynamics and Burgers shock waves.
基金supported by“Undergraduate Innovation and Entrepreneurship Training Program”at Harbin Institute of Technology。
文摘Complex plasma fluctuation processes have been extensively studied in many aspects,especially lattice waves in strongly coupled plasma crystals,which are of great significance for understanding fundamental physical phenomena.A challenge of experimental investigations in two-dimensional strongly coupled complex plasma crystals is to keep the main body and foreign particles of different masses on the same horizontal plane.To solve the problem,we have proposed a potential well formed by two negatively biased grids to bind the negatively charged particles in a two-dimensional(2D)plane,thus achieving a 2D plasma crystal in the microgravity environment.The study of such phenomena in complex plasma crystals under microgravity environment then becomes possible.In this paper,we focus on the continuum spectrum,including both phonon and optic branches of the impurity mode in a 2D system in microgravity environments.The results show the dispersion relation of the longitudinal and transverse impurity oscillation modes and their properties.Considering the macroscopic visibility of complex mesoscopic particle lattices,theoretical and experimental studies on this kind of complex plasma systems will help us further understand the physical nature of a wide range of condensed matters.
文摘We focus on molecular dynamics simulated two-dimensional complex plasma crystals. We use rigid walls as a confinement force and produce square and rectangular crystals. We report various types of two-row crystals. The narrow and long crystals are likely to be used as wigglers; therefore, we simulate such crystals. Also, we analyze the electric fields of simulated crystals. A bit change in lattice parameters can change the internal structures of crystals and their electric fields notably. These parameters are the number of grains, grains charge, length, and width of the crystal. With the help of electric fields, we show the details of crystal structures.
文摘In this paper we have developed a model to study the role of both electron and ion nonthermalities on dust acoustic wave propagation in a complex plasma in presence of positively charged dust grains. Secondary electron emission from dust grains has been considered as the source of positive dust charging. As secondary emission current depends on the flux of primary electrons, nonthermality of primary electrons changes the expression of secondary emission current from that of earlier work where primary electrons were thermal. Expression of nonthermal electron current flowing to the positively charged dust grains and consequently the expression of secondary electron current flowing out of the dust grains have been first time calculated in this paper, whereas the expression for nonthermal ion current flowing to the positively charged dust grains is present in existing literature. Dispersion relation of dust acoustic wave has been derived. From this dispersion relation real frequency and growth rate of the wave have been calculated. Results have been plotted for different strength of nonthermalities of electrons and ions.
文摘A rigorous theoretical investigation of linear dust ion acoustic (DIA) solitary waves in an unmagnetized complex plasma consisting of ion and ion beam fluids, nonthermal electrons that are Cairns distributed and immobile dust particles were undertaken. It was found out that, for large beam speeds, three stable modes propagated as solitary waves in the beam plasma. These were the “Fast”, “Slow” and “Ion-acoustic” modes. For two stream instability to occur between ion and ion beam, it is shown that or when .
基金Supported by the National Natural Science Foundation China under Grant Nos 40390150, 10175013, 10010760807, 10160420799, 40390155, 40228006 and 10575018.
文摘The effects of thermionic emission on dust-acoustic solitons with a very small but finite amplitude in a dustelectron plasma are studied using the reductive perturbation technique. The self-consistent variation of dust charge is taken into account. It is shown that the thermionic emission could significantly increase the dust positive charge. The dependences of the phase velocity, amplitude, and width of such solitons on the dust temperature and the dust work function of dust material are plotted and discussed.
基金supported by National Natural Science Foundation of China(Nos.12175159 and 11875199)the 1000 Youth Talents Plan,startup funds from Soochow Universitythe Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical definition of the ratio of the internal pressure/stress to the volume strain. Under various conditions, the bulk moduli obtained agree with the previous theoretical derivations from completely different approaches. It is found that the bulk moduli of2D Yukawa solids and liquids are almost independent of the system temperature and the external compressional frequency.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12075315 and 11675261)。
文摘The effect of the number of defect particles on the structure and dispersion relations of a two-dimensional(2D) dust lattice is studied by molecular dynamics(MD) simulation. The dust lattice structures are characterized by particle distribution, nearest neighbor configuration and pair correlation function. The current autocorrelation function, the dispersion relation and sound speed are used to represent the wave properties. The wave propagation of the dust lattice closely relates to the lattice structure. It shows that the number of defect particles can affect the dust lattice local structure and then affect the dispersion relations of waves propagating in it. The presence of defect particles has a greater effect on the transverse waves than on the longitudinal waves of the dust lattice. The appropriate number of defect particles can weaken the anisotropy property of the lattice.
文摘The process of complex granules prepared by HF plasma spraying through axial feeding and thermodynamic analysis of the process is described. The densification factors of complex granules is also discussed, the result of which coincides with the test results. The process has the advantages of simple processing, convenient operation, high purity and wide applications. It is an effective way for producing complex granules by multicomponent metallic powders and ceramic metal powders.
