This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to f...This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to flow into the chamber from the upper showerhead electrode.The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered.This is represented by the pressure volume work term of the gas energy converse equation.The gas advection leads to the gas temperature sink at the gas inlet,hence a large gas temperature gradient is formed.The thermophoresis relies on the gas temperature gradient,and causes the profile of nanoparticle density to vary from a double-peak structure to a single-peak one.The gas advection influences the properties of electron density and temperature as well and causes the drift-ambipolar mode profile of electron density asymmetric.In the bulk region,i.e.away from the inlet,the gas advection is more like one isovolumetric compression,which slightly increases the temperature of the gas medium at consuming its kinetic energy.展开更多
We study the existence of global-in-time classical solutions for the one-dimensional nonisentropic compressible Euler system for a dusty gas with large initial data.Using the characteristic decomposition method propos...We study the existence of global-in-time classical solutions for the one-dimensional nonisentropic compressible Euler system for a dusty gas with large initial data.Using the characteristic decomposition method proposed by Li et al.(Commun Math Phys 267:1–12,2006),we derive a group of characteristic decompositions for the system.Using these characteristic decompositions,we find a sufficient condition on the initial data to ensure the existence of global-in-time classical solutions.展开更多
In this paper, we consider the dynamics of modulated waves in an unmagnetized, non-isothermal self-gravitating dusty plasma model. The varying charge on the moving dust, as it moves in and out of regions of differing ...In this paper, we consider the dynamics of modulated waves in an unmagnetized, non-isothermal self-gravitating dusty plasma model. The varying charge on the moving dust, as it moves in and out of regions of differing electron and ion densities (due to changes in the electrostatic potential), will be out of phase with the equilibrium charge. The effect of the dust is to increase the phase velocity of the ion-acoustic (IA) waves i.e. decrease the Landau damping. In the low-amplitude limit and weak damping, we apply the reductive perturbation method on the model that resulted to the complex cubic Ginzburg-Landau (CCGL) equation. From these results, it is observed that, the plasma parameters strongly influence the properties of the solitary wave solution namely, the amplitude and the width. The effects of non-isothermal electrons, gravity, dust charge fluctuations and drifting motion on the ion-acoustic solitary waves are discussed with application in astrophysical contexts. It is also observed that the number of charges residing on the dust grains increases the modulational stability of the plane waves in the plasma, thus, enhancing the generation of modulated waves.展开更多
The present study is focused on the unsteady two-phase flow of blood in a cylindrical region.Blood is taken as a counter-example of Brinkman type fluid containing magnetic(dust)particles.The oscillating pressure gradi...The present study is focused on the unsteady two-phase flow of blood in a cylindrical region.Blood is taken as a counter-example of Brinkman type fluid containing magnetic(dust)particles.The oscillating pressure gradient has been considered because for blood flow it is necessary to investigate in the form of a diastolic and systolic pressure.The transverse magnetic field has been applied externally to the cylindrical tube to study its impact on both fluids as well as particles.The system of derived governing equations based on Navier Stoke’s,Maxwell and heat equations has been generalized using the well-known Caputo–Fabrizio(C–F)fractional derivative.The considered fractional model has been solved analytically using the joint Laplace and Hankel(L&H)transformations.The effect of various physical parameters such as fractional parameter,Gr,M andγ on blood and magnetic particles has been shown graphically using the Mathcad software.The fluid behaviour is thinner in fractional order as compared to the classical one.展开更多
Boundary layer flows and melting heat transfer of a Prandtl fluid over a stretching surface in the presence of fluid particle suspensions has been investigated.The converted set of boundary layer equations are solved ...Boundary layer flows and melting heat transfer of a Prandtl fluid over a stretching surface in the presence of fluid particle suspensions has been investigated.The converted set of boundary layer equations are solved numerically by RKF-45 method.Obtained numerical results for flow and heat transfer characteristics are deliberated for various physical parameters.Furthermore,the skin friction coefficient and Nusselt number are also presented in Tabs.2 and 3.It is found that the heat transfer rates are advanced in occurrence of nonlinear radiation compered to linear radiation.Also,it is noticed that velocity and temperature profile increases by increasing Prandtl parameter.展开更多
In the framework of the two-fluid model,a hypersonic flow of anonuniform dusty gas with low inertial(non-depositing)particles around a bluntbody is considered.The particle mass concentration is assumed to be small,so ...In the framework of the two-fluid model,a hypersonic flow of anonuniform dusty gas with low inertial(non-depositing)particles around a bluntbody is considered.The particle mass concentration is assumed to be small,so thatthe effect of particles on the carrier phase is significant only inside the boundarylayer where the particles accumulate.Stepshaped and harmonic nonuniformities ofthe particle concentration ahead of the bow shock wave are considered and the corre-sponding nonstationary distributions of the particle concentration in the shock layerare studied.On the basis of numerical study of nonstationary two-phase boundarylayer equations derived by the matched asymptotic expansion method,the effects offree-stream particle concentration nonuniformities on the thermal flux and the frictioncoefficient in the neighborhood of stagnation point are investigated,in particular,themost'dangerous'nonuniformity periods are found.展开更多
An analysis has been carried out to study the effect of hydrodynamic laminar boundary layer flow and heat transfer of a dusty fluid over an unsteady stretching surface in the presence of non-uniform heat source/sink. ...An analysis has been carried out to study the effect of hydrodynamic laminar boundary layer flow and heat transfer of a dusty fluid over an unsteady stretching surface in the presence of non-uniform heat source/sink. Heat transfer characteristics are examined for two different kinds of boundary conditions, namely 1) variable wall temperature and 2) variable heat flux. The governing partial differential equations are transformed to system of ordinary differential equations. These equations are solved numerically by applying RKF-45 method. The effects of various physical parameters such as magnetic parameter, dust interaction parameter, number density, Prandtl number, Eckert number, heat source/sink parameter and unsteadiness parameter on velocity and temperature profiles are studied.展开更多
The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is...The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is characterized by the scattering laser intensity and fractal dimension. The comparisons of dust particles and scattering laser intensity obtained at different rf powers are presented. The three-dimensional distribution of dust particles is also given. These results provide an experimental basis for dust growth investigation.展开更多
The particle structure of a complex system has been explored through a unique Evans' s homogenous nonequilibrium molecular dynamics(HNEMD) simulation technique. The crystalline order–disorder structures(OD-struct...The particle structure of a complex system has been explored through a unique Evans' s homogenous nonequilibrium molecular dynamics(HNEMD) simulation technique. The crystalline order–disorder structures(OD-structures) and the corresponding energies of three-dimensional(3 D) nonideal complex systems(NICSs) have been measured over a wide range of plasma states(■, κ) for a body-centered cubic(BCC) structure. The projected technique provides accurate ODstructures with fast convergence and applicable to very small size effect for different temperatures(≡ 1/■) and constant force field(F~*) values. The OD-structure obtained through HNEMD approach is found to be reasonable agreement and more reliable than those earlier identified by simulation approaches and experimental data of NICSs. New simulations of OD-structures show that dusty plasma remains in crystalline(strongly coupled) state at lower temperature and constant F*values, for the whole simulation runs. Our investigations show that the crystalline structure is changed and the particle structure switches from intermediate to disorder(nonideal gaseous) state with an increase of the system's temperature. It has been shown that the long range order shifts toward lower temperature with increasing κ. The presented technique exhibits that the potential energy has a maximum value when the dusty plasma remains in crystalline states(low temperatures),which confirms earlier 3 D simulation results.展开更多
The electron kinetic model for investigating the transport and ionization rate coefficients of argon glow discharge dusty plasma is developed from the Boltzmann equation.Both of the electron-neutral and electron-dust ...The electron kinetic model for investigating the transport and ionization rate coefficients of argon glow discharge dusty plasma is developed from the Boltzmann equation.Both of the electron-neutral and electron-dust collisions are considered as collision terms in the kinetic equation.The kinetic equation is simplified by employing the local approximation and nonlocal approach under the same discharge conditions,and the corresponding simplified kinetic equations are known as local and nonlocal kinetic equations respectively.Then the electron energy distribution function(EEDF)is obtained by numerically solving the local and nonlocal kinetic equations and the dust charging equations simultaneously.Based on the obtained EEDFs,the effective electron temperature,electron mobility,electron diffusion coefficient and ionization rate coefficient are calculated for different discharge conditions.It is shown that the EEDFs calculated from the local kinetic model clearly differ from the nonlocal EEDFs and both the local and nonlocal EEDFs are also clearly different with Maxwellian distributions.The appearance of dust particles results in an obvious decrease of high energy electrons and increase of low energy electrons when axial electric field is low.With the increase of axial electric field,the influence of dust particles on the EEDFs becomes smaller.The electron mobility and diffusion coefficients calculated on the basis of local and nonlocal EEDFs do not differ greatly to the dust-free ones.While,when dust density nd=10^6 cm^?3,the electron mobility increases obviously compared with the dust-free results at low axial electric field and decreases with the increasing axial electric field until they are close to the dust-free ones.Meanwhile,electron diffusion coefficients for dusty case become smaller and decrease with the increasing axial electric field.The ionization rate coefficients decrease when dust particles are introduced and they approach the dust-free results gradually with the increasing axial electric field.展开更多
The magnetohydrodynamic(MHD)mixed convection flow past a shrinking vertical sheet with thermal radiation is considered.Besides,the effects of Cu-Al_(2)O_(3) nanoparticles and dust particles are considered.The similari...The magnetohydrodynamic(MHD)mixed convection flow past a shrinking vertical sheet with thermal radiation is considered.Besides,the effects of Cu-Al_(2)O_(3) nanoparticles and dust particles are considered.The similarity variables reduce the governing equations to the similarity equations,which are then solved numerically.The outcome shows that,for the shrinking case,the solutions are not unique.The rate of heat transfer and the friction factor enlarge with increasing the values of the copper nanoparticle volume fraction as well as the magnetic parameter.Meanwhile,the assisting flow and the rise of the thermal radiation reduce these quantities.Two solutions are found,and the boundary layer separation is dependent on the mixed convection parameter.展开更多
To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and...To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips.Dusty plasma with dusts(a generation rate of 3μg s-1 and a size of 1–10μm)was produced via interactions between a high-power laser beam and a full tungsten target.As ne increases,the scale of the effects of dusty plasma injection on magnetized plasmas was decreased.Also,the duration of transient fluctuation was reduced.For numerical estimation of plasma density perturbation due to dusty plasma injection,the result was 10%at a core region of the magnetized plasma with ne of(2–5)×10^11 cm^-3 at steady state condition.展开更多
By designing a metal saw structure,both negative and positive rotations of dust vortices are obtained experimentally.With increasing gas pressure,the dust vortex undergoes different spatial distribution from dense dus...By designing a metal saw structure,both negative and positive rotations of dust vortices are obtained experimentally.With increasing gas pressure,the dust vortex undergoes different spatial distribution from dense dust cloud to dust void,then to dust chain.The transition between the negative and positive rotations of dust vortices is reversible and controllable by changing the gas pressure/input power.The underlying mechanism of this transition is preliminarily explored.展开更多
Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized plasma.The plasma consists of inertial warm negatively charged massive dusts,positively...Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized plasma.The plasma consists of inertial warm negatively charged massive dusts,positively charged dusts,superthermal kappa distributed electrons,and isothermal ions.The extended Poincaré–Lighthill–Kuo(e PLK)method is employed for the drivation of two-sided Korteweg–de Vries(KdV)equations(KdVEs).The Kd V soliton solutions are derived by using the hyperbolic secant method.The effects of superthermality index of electrons,temperature ratio of isothermal ion to electron,and the density ratio of isothermal ions to negatively charged massive dusts on nonlinear coefficients are investigated.The effects of oblique collision on amplitude,phase shift,and potential profile of right traveling solitons of DA waves are also studied.The study reveals that the new nonlinear wave structures are produced in the colliding region due to head-on collision of the two counter propagating DA waves.The nonlinearity is found to decrease with the increasing density ratio of ion to negative dust in the critical region.The phase shifts decrease(increase)with increasing the temperature ratio of ion to electron(κe).The hump(compressive,κe<κec)and dipshaped(rarefactive,κe>κec)solitons are produced depending on the angle(θ)of oblique collision between the two waves.展开更多
The attenuation characteristics of obliquely incident electromagnetic(EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar-Gross-Krook(BGK) collision model.Accord...The attenuation characteristics of obliquely incident electromagnetic(EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar-Gross-Krook(BGK) collision model.According to the kinetic equation and the charging theory,the total complex dielectric constant of the weakly ionized dusty plasma is derived by considering that the minimum velocity of the electron accessible to the dust particle surface is non-zero and the second potential part of the collision cross-section contributes to the charging.The attenuation characteristics within the modified model are compared with those within the traditional model.The influence of the dusty plasma parameters and the incident angle of EM waves on the attenuation in weakly ionized dusty plasma is further analyzed.Finally,the influence of different reentry heights on the attenuation characteristics of the obliquely incident EM wave is discussed.The results show that the effect of the minimum electron velocity and the second term of the collision cross-section on the attenuation characteristics of EM waves cannot be ignored.When the dust density and dust radius are changed,the trends of the attenuation of obliquely incident EM waves are consistent,but the influence of dust density is weaker than that of dust radius due to the constraint of orbit-limited motion(OLM) theory.The plasma thickness,electron density,and incident angle are proportional to the attenuation amplitude of EM waves.The effect of different reentry heights on the attenuation obliquely incident EM waves is related to the electron density and plasma thickness.展开更多
Linear and nonlinear dust acoustic(DA)waves have been investigated in an opposite polarity dusty plasma comprising negatively and positively charged dust grains,Maxwellian electrons and ions,including the generalized ...Linear and nonlinear dust acoustic(DA)waves have been investigated in an opposite polarity dusty plasma comprising negatively and positively charged dust grains,Maxwellian electrons and ions,including the generalized polarization force effect.The properties of linear DA waves have been significantly altered by the dual dust polarity and polarization force.Large amplitude DA solitons have been discussed in the framework of the Sagdeev potential technique.Our results show that both rarefactive and compressive solitons can exist in such a dusty plasma.The basic features of the Sagdeev potential have been examined under the effect of the polarization force parameter R,the ratio of the charge number of the positive dust to that of the negative dust Z,and the Mach number M.The results show that these parameters play a significant role in determining the region of existence of large amplitude DA solitons.展开更多
In this paper,numerical investigations for peristaltic motion of dusty nanofluids in a curved channel are performed.Two systems of partial differential equations are presented for the nanofluid and dusty phases and th...In this paper,numerical investigations for peristaltic motion of dusty nanofluids in a curved channel are performed.Two systems of partial differential equations are presented for the nanofluid and dusty phases and then the approximations of the long wave length and low Reynolds number are applied.The physical domain is transformed to a rectangular computational model using suitable grid transformations.The resulting systems are solved numerically using shooting method and mathematical forms for the pressure distributions are introduced.The controlling parameters in this study are the thermal buoyancy parameter G_(r),the concentration buoyancy parameter Gc,the amplitude ratio,the Eckert number Ec,the thermophoresis parameter N_(t) and the Brownian motion parameter Nb and the dusty parameters D_(s);α_(s).The obtained results revealed that an increase in the Eckert number enhances the temperature of the fluid and dusty particles while the nanoparticle volume fraction is reduced.Also,both of the temperature and nanoparticles volume fraction are supported by the growing of the Brownian motion parameter.展开更多
For the sake of investigating the drift coherent vortex structure in an inhomogeneous dense dusty magnetoplasma,using the quantum hydrodynamic model a nonlinear controlling equation is deduced when the collision effec...For the sake of investigating the drift coherent vortex structure in an inhomogeneous dense dusty magnetoplasma,using the quantum hydrodynamic model a nonlinear controlling equation is deduced when the collision effect is considered.New vortex solutions of the electrostatic potential are obtained by a special transformation method, and three evolutive cases of monopolar vortex chains with spatial and temporal distribution are analyzed by representative parameters. It is found that the collision frequency, particle density, drift velocity, dust charge number, electron Fermi wavelength, quantum correction,and quantum parameter are all influencing factors of the vortex evolution. Compared to the uniform dusty system, the vortex solutions of the inhomogeneous system present richer spatial evolution and physical meaning. These results may explain corresponding vortex phenomena and support beneficial references for the dense dusty plasma atmosphere.展开更多
基金supported by National Natural Science Foundation of China(Nos.11805107 and 12275039)the Fundamental Research Funds in Heilongjiang Provincial Universities of China(No.135509124)the Graduate Innovation Foundation of Qiqihar University(No.YJSCX2022014)。
文摘This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to flow into the chamber from the upper showerhead electrode.The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered.This is represented by the pressure volume work term of the gas energy converse equation.The gas advection leads to the gas temperature sink at the gas inlet,hence a large gas temperature gradient is formed.The thermophoresis relies on the gas temperature gradient,and causes the profile of nanoparticle density to vary from a double-peak structure to a single-peak one.The gas advection influences the properties of electron density and temperature as well and causes the drift-ambipolar mode profile of electron density asymmetric.In the bulk region,i.e.away from the inlet,the gas advection is more like one isovolumetric compression,which slightly increases the temperature of the gas medium at consuming its kinetic energy.
基金supported by the National Natural Science Foundation of China(12071278).
文摘We study the existence of global-in-time classical solutions for the one-dimensional nonisentropic compressible Euler system for a dusty gas with large initial data.Using the characteristic decomposition method proposed by Li et al.(Commun Math Phys 267:1–12,2006),we derive a group of characteristic decompositions for the system.Using these characteristic decompositions,we find a sufficient condition on the initial data to ensure the existence of global-in-time classical solutions.
文摘In this paper, we consider the dynamics of modulated waves in an unmagnetized, non-isothermal self-gravitating dusty plasma model. The varying charge on the moving dust, as it moves in and out of regions of differing electron and ion densities (due to changes in the electrostatic potential), will be out of phase with the equilibrium charge. The effect of the dust is to increase the phase velocity of the ion-acoustic (IA) waves i.e. decrease the Landau damping. In the low-amplitude limit and weak damping, we apply the reductive perturbation method on the model that resulted to the complex cubic Ginzburg-Landau (CCGL) equation. From these results, it is observed that, the plasma parameters strongly influence the properties of the solitary wave solution namely, the amplitude and the width. The effects of non-isothermal electrons, gravity, dust charge fluctuations and drifting motion on the ion-acoustic solitary waves are discussed with application in astrophysical contexts. It is also observed that the number of charges residing on the dust grains increases the modulational stability of the plane waves in the plasma, thus, enhancing the generation of modulated waves.
文摘The present study is focused on the unsteady two-phase flow of blood in a cylindrical region.Blood is taken as a counter-example of Brinkman type fluid containing magnetic(dust)particles.The oscillating pressure gradient has been considered because for blood flow it is necessary to investigate in the form of a diastolic and systolic pressure.The transverse magnetic field has been applied externally to the cylindrical tube to study its impact on both fluids as well as particles.The system of derived governing equations based on Navier Stoke’s,Maxwell and heat equations has been generalized using the well-known Caputo–Fabrizio(C–F)fractional derivative.The considered fractional model has been solved analytically using the joint Laplace and Hankel(L&H)transformations.The effect of various physical parameters such as fractional parameter,Gr,M andγ on blood and magnetic particles has been shown graphically using the Mathcad software.The fluid behaviour is thinner in fractional order as compared to the classical one.
文摘Boundary layer flows and melting heat transfer of a Prandtl fluid over a stretching surface in the presence of fluid particle suspensions has been investigated.The converted set of boundary layer equations are solved numerically by RKF-45 method.Obtained numerical results for flow and heat transfer characteristics are deliberated for various physical parameters.Furthermore,the skin friction coefficient and Nusselt number are also presented in Tabs.2 and 3.It is found that the heat transfer rates are advanced in occurrence of nonlinear radiation compered to linear radiation.Also,it is noticed that velocity and temperature profile increases by increasing Prandtl parameter.
基金The project supported by the Russian Foundation for Basic Research(project No.96-01-00313)the National Natural Science Foundation of China(joint RFBR-NSFC grant No.96-01-00017c)
文摘In the framework of the two-fluid model,a hypersonic flow of anonuniform dusty gas with low inertial(non-depositing)particles around a bluntbody is considered.The particle mass concentration is assumed to be small,so thatthe effect of particles on the carrier phase is significant only inside the boundarylayer where the particles accumulate.Stepshaped and harmonic nonuniformities ofthe particle concentration ahead of the bow shock wave are considered and the corre-sponding nonstationary distributions of the particle concentration in the shock layerare studied.On the basis of numerical study of nonstationary two-phase boundarylayer equations derived by the matched asymptotic expansion method,the effects offree-stream particle concentration nonuniformities on the thermal flux and the frictioncoefficient in the neighborhood of stagnation point are investigated,in particular,themost'dangerous'nonuniformity periods are found.
文摘An analysis has been carried out to study the effect of hydrodynamic laminar boundary layer flow and heat transfer of a dusty fluid over an unsteady stretching surface in the presence of non-uniform heat source/sink. Heat transfer characteristics are examined for two different kinds of boundary conditions, namely 1) variable wall temperature and 2) variable heat flux. The governing partial differential equations are transformed to system of ordinary differential equations. These equations are solved numerically by applying RKF-45 method. The effects of various physical parameters such as magnetic parameter, dust interaction parameter, number density, Prandtl number, Eckert number, heat source/sink parameter and unsteadiness parameter on velocity and temperature profiles are studied.
基金Supported by the National Natural Science Foundation of China under Grant No 11675261
文摘The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is characterized by the scattering laser intensity and fractal dimension. The comparisons of dust particles and scattering laser intensity obtained at different rf powers are presented. The three-dimensional distribution of dust particles is also given. These results provide an experimental basis for dust growth investigation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11505286 and 11805272)
文摘The particle structure of a complex system has been explored through a unique Evans' s homogenous nonequilibrium molecular dynamics(HNEMD) simulation technique. The crystalline order–disorder structures(OD-structures) and the corresponding energies of three-dimensional(3 D) nonideal complex systems(NICSs) have been measured over a wide range of plasma states(■, κ) for a body-centered cubic(BCC) structure. The projected technique provides accurate ODstructures with fast convergence and applicable to very small size effect for different temperatures(≡ 1/■) and constant force field(F~*) values. The OD-structure obtained through HNEMD approach is found to be reasonable agreement and more reliable than those earlier identified by simulation approaches and experimental data of NICSs. New simulations of OD-structures show that dusty plasma remains in crystalline(strongly coupled) state at lower temperature and constant F*values, for the whole simulation runs. Our investigations show that the crystalline structure is changed and the particle structure switches from intermediate to disorder(nonideal gaseous) state with an increase of the system's temperature. It has been shown that the long range order shifts toward lower temperature with increasing κ. The presented technique exhibits that the potential energy has a maximum value when the dusty plasma remains in crystalline states(low temperatures),which confirms earlier 3 D simulation results.
基金National Natural Science Foundation of China(Nos.11775062 and 61601419)the Key Laboratory Foundation of National Key Laboratory of Electromagnetic Environment(No.614240319010303).
文摘The electron kinetic model for investigating the transport and ionization rate coefficients of argon glow discharge dusty plasma is developed from the Boltzmann equation.Both of the electron-neutral and electron-dust collisions are considered as collision terms in the kinetic equation.The kinetic equation is simplified by employing the local approximation and nonlocal approach under the same discharge conditions,and the corresponding simplified kinetic equations are known as local and nonlocal kinetic equations respectively.Then the electron energy distribution function(EEDF)is obtained by numerically solving the local and nonlocal kinetic equations and the dust charging equations simultaneously.Based on the obtained EEDFs,the effective electron temperature,electron mobility,electron diffusion coefficient and ionization rate coefficient are calculated for different discharge conditions.It is shown that the EEDFs calculated from the local kinetic model clearly differ from the nonlocal EEDFs and both the local and nonlocal EEDFs are also clearly different with Maxwellian distributions.The appearance of dust particles results in an obvious decrease of high energy electrons and increase of low energy electrons when axial electric field is low.With the increase of axial electric field,the influence of dust particles on the EEDFs becomes smaller.The electron mobility and diffusion coefficients calculated on the basis of local and nonlocal EEDFs do not differ greatly to the dust-free ones.While,when dust density nd=10^6 cm^?3,the electron mobility increases obviously compared with the dust-free results at low axial electric field and decreases with the increasing axial electric field until they are close to the dust-free ones.Meanwhile,electron diffusion coefficients for dusty case become smaller and decrease with the increasing axial electric field.The ionization rate coefficients decrease when dust particles are introduced and they approach the dust-free results gradually with the increasing axial electric field.
基金Universiti Teknikal Malaysia Melaka and Universiti Kebangsaan Malaysia(No.DIP-2020-001)for funds。
文摘The magnetohydrodynamic(MHD)mixed convection flow past a shrinking vertical sheet with thermal radiation is considered.Besides,the effects of Cu-Al_(2)O_(3) nanoparticles and dust particles are considered.The similarity variables reduce the governing equations to the similarity equations,which are then solved numerically.The outcome shows that,for the shrinking case,the solutions are not unique.The rate of heat transfer and the friction factor enlarge with increasing the values of the copper nanoparticle volume fraction as well as the magnetic parameter.Meanwhile,the assisting flow and the rise of the thermal radiation reduce these quantities.Two solutions are found,and the boundary layer separation is dependent on the mixed convection parameter.
基金National R&D Program through the Nation Research Foundation of Korea(NRF)funded by the Ministry of Education(2017R1D1A1B03033076)National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning(2019M1A7A1A03088471).
文摘To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips.Dusty plasma with dusts(a generation rate of 3μg s-1 and a size of 1–10μm)was produced via interactions between a high-power laser beam and a full tungsten target.As ne increases,the scale of the effects of dusty plasma injection on magnetized plasmas was decreased.Also,the duration of transient fluctuation was reduced.For numerical estimation of plasma density perturbation due to dusty plasma injection,the result was 10%at a core region of the magnetized plasma with ne of(2–5)×10^11 cm^-3 at steady state condition.
基金supported by National Natural Science Foundation of China (No. 11975089)the Program for National Defense Science and Technology Innovation Special Zone+1 种基金the Program for Young Top-Notch Talents of Hebei ProvinceHebei Natural Science Fund (Grant No. A2017201099).
文摘By designing a metal saw structure,both negative and positive rotations of dust vortices are obtained experimentally.With increasing gas pressure,the dust vortex undergoes different spatial distribution from dense dust cloud to dust void,then to dust chain.The transition between the negative and positive rotations of dust vortices is reversible and controllable by changing the gas pressure/input power.The underlying mechanism of this transition is preliminarily explored.
文摘Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized plasma.The plasma consists of inertial warm negatively charged massive dusts,positively charged dusts,superthermal kappa distributed electrons,and isothermal ions.The extended Poincaré–Lighthill–Kuo(e PLK)method is employed for the drivation of two-sided Korteweg–de Vries(KdV)equations(KdVEs).The Kd V soliton solutions are derived by using the hyperbolic secant method.The effects of superthermality index of electrons,temperature ratio of isothermal ion to electron,and the density ratio of isothermal ions to negatively charged massive dusts on nonlinear coefficients are investigated.The effects of oblique collision on amplitude,phase shift,and potential profile of right traveling solitons of DA waves are also studied.The study reveals that the new nonlinear wave structures are produced in the colliding region due to head-on collision of the two counter propagating DA waves.The nonlinearity is found to decrease with the increasing density ratio of ion to negative dust in the critical region.The phase shifts decrease(increase)with increasing the temperature ratio of ion to electron(κe).The hump(compressive,κe<κec)and dipshaped(rarefactive,κe>κec)solitons are produced depending on the angle(θ)of oblique collision between the two waves.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U20B2059 and 61627901)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.61621005)+4 种基金the Natural Science Foundation of Shaanxi Province of China(Grant No.2019JM-206)the National Key Laboratory Foundation of China(Grant No.HTKJ2019KL504014)the Fundamental Research Funds for the Central Universities,Chinathe Innovation Fund of Xidian University and the 111 Project(Grant No.B17035)。
文摘The attenuation characteristics of obliquely incident electromagnetic(EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar-Gross-Krook(BGK) collision model.According to the kinetic equation and the charging theory,the total complex dielectric constant of the weakly ionized dusty plasma is derived by considering that the minimum velocity of the electron accessible to the dust particle surface is non-zero and the second potential part of the collision cross-section contributes to the charging.The attenuation characteristics within the modified model are compared with those within the traditional model.The influence of the dusty plasma parameters and the incident angle of EM waves on the attenuation in weakly ionized dusty plasma is further analyzed.Finally,the influence of different reentry heights on the attenuation characteristics of the obliquely incident EM wave is discussed.The results show that the effect of the minimum electron velocity and the second term of the collision cross-section on the attenuation characteristics of EM waves cannot be ignored.When the dust density and dust radius are changed,the trends of the attenuation of obliquely incident EM waves are consistent,but the influence of dust density is weaker than that of dust radius due to the constraint of orbit-limited motion(OLM) theory.The plasma thickness,electron density,and incident angle are proportional to the attenuation amplitude of EM waves.The effect of different reentry heights on the attenuation obliquely incident EM waves is related to the electron density and plasma thickness.
文摘Linear and nonlinear dust acoustic(DA)waves have been investigated in an opposite polarity dusty plasma comprising negatively and positively charged dust grains,Maxwellian electrons and ions,including the generalized polarization force effect.The properties of linear DA waves have been significantly altered by the dual dust polarity and polarization force.Large amplitude DA solitons have been discussed in the framework of the Sagdeev potential technique.Our results show that both rarefactive and compressive solitons can exist in such a dusty plasma.The basic features of the Sagdeev potential have been examined under the effect of the polarization force parameter R,the ratio of the charge number of the positive dust to that of the negative dust Z,and the Mach number M.The results show that these parameters play a significant role in determining the region of existence of large amplitude DA solitons.
基金the Deanship of Scientific Research atKing Khalid University for funding this work through research groups program under Grant Number(R.G.P2/72/41).
文摘In this paper,numerical investigations for peristaltic motion of dusty nanofluids in a curved channel are performed.Two systems of partial differential equations are presented for the nanofluid and dusty phases and then the approximations of the long wave length and low Reynolds number are applied.The physical domain is transformed to a rectangular computational model using suitable grid transformations.The resulting systems are solved numerically using shooting method and mathematical forms for the pressure distributions are introduced.The controlling parameters in this study are the thermal buoyancy parameter G_(r),the concentration buoyancy parameter Gc,the amplitude ratio,the Eckert number Ec,the thermophoresis parameter N_(t) and the Brownian motion parameter Nb and the dusty parameters D_(s);α_(s).The obtained results revealed that an increase in the Eckert number enhances the temperature of the fluid and dusty particles while the nanoparticle volume fraction is reduced.Also,both of the temperature and nanoparticles volume fraction are supported by the growing of the Brownian motion parameter.
基金supported by the National Natural Science Foundation of China(Grant Nos.11365017,11465015,11405110,11305031,and 11404214)the Technology Landing Project of the Education Department of Jiangxi Province of China(Grant No.KJLD13086)
文摘For the sake of investigating the drift coherent vortex structure in an inhomogeneous dense dusty magnetoplasma,using the quantum hydrodynamic model a nonlinear controlling equation is deduced when the collision effect is considered.New vortex solutions of the electrostatic potential are obtained by a special transformation method, and three evolutive cases of monopolar vortex chains with spatial and temporal distribution are analyzed by representative parameters. It is found that the collision frequency, particle density, drift velocity, dust charge number, electron Fermi wavelength, quantum correction,and quantum parameter are all influencing factors of the vortex evolution. Compared to the uniform dusty system, the vortex solutions of the inhomogeneous system present richer spatial evolution and physical meaning. These results may explain corresponding vortex phenomena and support beneficial references for the dense dusty plasma atmosphere.