Fokker-Planck description of particle charging in ionized gases

Matsoukas, Themis; Russell, Marc

doi:10.1103/physreve.55.991

Cited by 61 publications

(57 citation statements)

References 25 publications

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“…These fluctuations always exist even in a steady-state uniform plasma 2 . Dust charge fluctuations have been investigated by many researchers [3][4][5][6][7][8][9] . In a dusty plasma, there are many phenomena that dust charge fluctuations can be considered as a reason for them such as heating of dust particles system [10][11][12] , instability of lattice oscillations in a low-pressure gas discharge 13,14 , and the formation of the shock waves in dusty plasmas 15 .…”

Section: Introductionmentioning

confidence: 99%

Memory effects in the velocity relaxation process of the dust particle in dusty plasma

Ghannad

Pajouh

2017

Physics of Plasmas

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In this paper, by comparing the time scales associated with the velocity relaxation and correlation time of the random force due to dust charge fluctuations, memory effects in the velocity relaxation of an isolated dust particle exposed to the random force due to dust charge fluctuations are considered, and the velocity relaxation process of the dust particle is considered as a non-Markovian stochastic process. Considering memory effects in the velocity relaxation process of the dust particle yields a retarded friction force, which is introduced by a memory kernel in the fractional Langevin equation. The fluctuation-dissipation theorem for the dust grain is derived from this equation. The mean-square displacement and the velocity autocorrelation function of the dust particle are obtained, and their asymptotic behavior, the dust particle temperature due to charge fluctuations, and the diffusion coefficient are studied in the long-time limit. As an interesting feature, it is found that by considering memory effects in the velocity relaxation process of the dust particle, fluctuating force on the dust particle can cause an anomalous diffusion in a dusty plasma. In this case, the mean-square displacement of the dust grain increases slower than linearly with time, and the velocity autocorrelation function decays as a power-law instead of the exponential decay. Finally, in the Markov limit, these results are in good agreement with those obtained from previous works for Markov (memoryless) process of the velocity relaxation.

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Section: Introductionmentioning

confidence: 99%

Memory effects in the velocity relaxation process of the dust particle in dusty plasma

Ghannad

Pajouh

2017

Physics of Plasmas

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“…Particulate materials in plasma, originally considered a nuisance, have over the past ten years been recognized for the wealth of physical phenomena they produce, such as stable confinement within the plasma sheath, long-range ordering, complex transport patterns, charge fluctuations, and selfsharpening size distributions. [16][17][18][19][20] One consequence of the high degree of charging is the resistance of such particles against aggregation, 20 a problem that usually plagues both liquid-and gas-phase processings. Particles introduced in the plasma remain in a nonaggregated form and it is even possible to promote breakup of aggregates by subjecting them to plasma charging.…”

Section: Introductionmentioning

confidence: 99%

A reaction model for plasma coating of nanoparticles by amorphous carbon layers

Yarin

Rovagnati

Mashayek

et al. 2006

Journal of Applied Physics

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A detailed chemical kinetics scheme of the reactions occurring in a CH4∕H2 plasma, namely, electron-neutral, ion-neutral, and neutral-neutral reactions, is implemented for the prediction of the species fluxes toward the surface of a submicron particle in a low-pressure environment. Surface reactions at the particle surface are also accounted for. Kinetic theory is applied in the collisionless region within a distance of one mean free path away from the particle, while continuum theory is implemented to solve for species transport in the outer region where reactive-diffusive phenomena occur. These regions are bounded by appropriate boundary conditions. The self-consistent electric field is obtained by solving the Poisson’s equation in the continuum region. The charged and neutral species distributions are calculated and the growth rate of the amorphous carbon layer at the particle surface, as well as particle charging, are predicted. The predicted growth rate is within the range of experimental data from literature for similar conditions. This shows that the model reflects rather accurately the complicated physicochemical phenomena occurring in real systems.

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“…Particles accumulate a net charge through continuous bombardment by ions and electrons, a stochastic process that results in a Gaussian distribution of charges. [19][20][21] In principle, charging currents require the calculation of ion and electron trajectories originating from infinity and terminating on the particle surface. This calculation is simplified considerably under the assumptions of the orbit-motion limit ͑OML͒.…”

Section: Introductionmentioning

confidence: 99%

Nanowire charging in collisionless plasma

Shahravan

Lucas

Matsoukas

2010

Journal of Applied Physics

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We calculate the collision cross section of a charged finite cylinder (nanowire) with a beam of ions and electrons in collisionless plasma. We find that, while the shape and area of the cross section has complex dependence on the charge and orientation of the nanowire relative to the charged beam, its orientational average has a remarkably simple form: for attractive interactions, it is a linear function of the electrostatic ratio qjqpe2/4πϵ0L0kT, where qje is the charge of the ions/electrons, qpe is the charge on the cylinder, L0 is the half-length of the nanowire, T is the temperature of the charged species, and ϵ0 is the permittivity of free space. This linearity persists into the repulsive regime up until the cross sectional area is reduced to about 5% of its value for neutral collisions. We calculate the corresponding charging currents and show that the charging behavior of the nanowire in Maxwellian plasma is described by an equivalent sphere whose radius depends only on the aspect ratio of the nanowire. For small aspect ratios, the equivalent sphere has the same surface area as the nanowire.

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Fokker-Planck description of particle charging in ionized gases

Cited by 61 publications

References 25 publications

Memory effects in the velocity relaxation process of the dust particle in dusty plasma

Memory effects in the velocity relaxation process of the dust particle in dusty plasma

A reaction model for plasma coating of nanoparticles by amorphous carbon layers

Nanowire charging in collisionless plasma

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