Ambipolar Diffusion in a Nonuniorm Plasma Containing Different Positive Ion Components

Wunderer, B.

doi:10.1109/tps.1978.4317148

Cited by 8 publications

(6 citation statements)

References 18 publications

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“…Multi-fluid models that neglect the inertia of the ions have been used [1][2][3][4]. This simplification yields a diffusion theory from which to calculate the distributions of the densities and fluxes of the various species within the plasmas.…”

Section: Introductionmentioning

confidence: 99%

Boundary value problems for multi-component plasmas and a generalized Bohm criterion

Valentini

Herrmann

1996

J. Phys. D: Appl. Phys.

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A multi-fluid model for bounded plasmas containing positive species of ions yields a p + 2-point boundary value problem (BVP) if steady state conditions, space charge effects and simple geometries are taken into account. Assuming cold ions, a two-point one follows. The number of boundary points is not increased if negative ions are included. Neglecting the space charge effects, the sheath edge can be defined at a non-removable singular point of the problem. Taking into account the space charge density, a generalized Bohm criterion can be formulated. The resulting complicated expression is reduced to a practicable form.

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Section: Introductionmentioning

confidence: 99%

Boundary value problems for multi-component plasmas and a generalized Bohm criterion

Valentini

Herrmann

1996

J. Phys. D: Appl. Phys.

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“…We now consider the situation with several types of positive ions and no negative ions [ 1 , 64 , 76 – 78 ]. The particle flux equations for electrons and two types of positive ions, labeled 1 and 2, are

and

Here the Γ j and n j are the fluxes and densities of ions 1 and 2 and the D j and μ j are the diffusion coefficients and mobilities for these ions.…”

Section: Effects Of Space Charge On Diffusion Of Electrons and Ionmentioning

confidence: 99%

“…These relationships were used by Phelps [ 77 ] to analyze the observed decay of helium ions and of electrons in the afterglow of a helium discharge. Note that the assumption of congruence, i.e., the equality of the ∇ n / n values for the electrons and both types of ions, is not generally applicable [ 1 , 78 ]. It should apply when nonlinear loss and production processes, such as electron-positive ion and positive ion-negative ion recombination, are negligible and the ions are distributed in the fundamental diffusion mode [ 1 , 77 ].…”

Section: Effects Of Space Charge On Diffusion Of Electrons and Ionmentioning

confidence: 99%

The diffusion of charged particles in collisional plasmas: Free and ambipolar diffusion at low and moderate pressures

Phelps¹

1990

J. RES. NATL. INST. STAN.

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The interpretation of measurements of the properties of weakly ionized plasmas in terms of diffusion of electrons and ions is reviewed both critically and tutorially. A particular effort is made to tie together various aspects of charged particle diffusion phenomena in quiescent, partially ionized plasmas. The concepts of diffusion length and effective diffusion coefficient and the treatment of partially reflecting boundaries are developed in the limit of the space-charge-free motion of the electrons or ions. A simplified derivation of the screening length for space charge electric fields is followed by a review of the conventional derivation of diffusion in the ambipolar limit. A discussion of the scaling parameters of the ratio of the diffusion length to the screening length and the ratio of the diffusion length to the ion mean-free-path leads to a map used to correlate published models covering the complete range of these parameters. The models of measurements of the diffusion of electrons, several types of positive ions, and negative ions are reviewed. The role of diffusion in the decay of charged particle densities and wall currents during the afterglow of a discharge is then considered. The effects of collapse of the space charge field and of diffusion cooling are reviewed. Finally, the application of the diffusion models to a number of different discharges is discussed.

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“…d -= a -Vi. Wunderer (1978), using balance equations for each type of ion, has shown that the physical situations for which the application of the proportionality condition can be a priori justified, are limited. For a stationary thermal plasma, the temperature profile being a monotonously decreasing function of r, we can obtain for the population number densities, according to the CLTE plasma composition and despite the influence of diffusion:…”

Section: Ambipolar Diffusion Currentsmentioning

confidence: 99%

Ambipolar diffusion in a nitrogen thermal plasma

Bacri¹,

Gomes²,

Eymard³

1985

J. Phys. D: Appl. Phys.

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Ambipolar Diffusion in a Nonuniorm Plasma Containing Different Positive Ion Components

Cited by 8 publications

References 18 publications

Boundary value problems for multi-component plasmas and a generalized Bohm criterion

Boundary value problems for multi-component plasmas and a generalized Bohm criterion

The diffusion of charged particles in collisional plasmas: Free and ambipolar diffusion at low and moderate pressures

Ambipolar diffusion in a nitrogen thermal plasma

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