Boundary layers in dense plasmas

Thornhill, L.D.; Desai, Prateen V.

doi:10.2514/6.1997-2405

Cited by 2 publications

(3 citation statements)

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“…The case corresponding to the condition 2 − 2ν − λ 1 > 0 leads to an intermediate region between the mean-free-path scale and the sheath scale. It was demonstrated by Thornhill (1996) that, at leading order, the solution on this scale collapses to a point. This result will need to be reexamined when first-order influences are considered.…”

Section: )mentioning

confidence: 97%

“…Also, in order to retain the leading-order balances in (3.18) and (3.19), it must hold that ν 1. It has been shown (Thornhill 1996) that the case corresponding to ν > 1 leads to a solution that is physically meaningless. Therefore only the case for ν = 1 is considered here.…”

Section: Solutions On the Mean-free-path Scalementioning

confidence: 99%

“…However, C 2 , and consequently the velocity at the sheath edge, remain undetermined. It can be shown (Thornhill 1996) that physically realizable (monotonic) solutions for the sheath potential can be obtained from this system only if u ∞ [(1 + δ T ) / (1 + δ m )] 1/2 , which is the two-temperature form of Bohm's criterion. However, on the mean-free-path scale, the existence of a field singularity leads to the condition u i00 (ζ → 0) = u ∞ [(1 + δ T ) / (1 + δ m )] 1/2 .…”

Section: )mentioning

confidence: 99%

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Asymptotically matched sheath and presheath in a dense plasma

Thornhill

Desai

1998

J. Plasma Phys.

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Asymptotically matched solutions for electron and ion density, electron and ion velocity, and electric potential are obtained in the boundary region of a dense low-temperature plasma adjacent to perfectly absorbing walls – walls that absorb, without reflection, incident electrons and ions. Leading-order composite solutions, valid throughout the boundary region, are constructed from solutions in three subdomains distinguished by different physical length scales: the geometric length, the ion mean free path and the Debye length. The composite solutions are used to assess the impact of electron–ion recombination in the ionization nonequilibrium region on sheath and presheath profiles, and on quantities evaluated at the wall. While, at leading order, the velocity profiles throughout the boundary region are not influenced by recombination, the density and potential profiles are significantly altered when recombination is included. These results show that the region of rapid change in these profiles lies closer to the wall when recombination is explicitly included in the model. The influence of recombination on the presheath potential, and consequently the wall potential, is found to scale as the natural logarithm of the recombination length. The broadening of the density profile results in a larger flux of ions accelerating through the sheath and impacting on the wall. The influence of recombination on the ion power flux to the wall is found to scale with the inverse recombination length. This scaling influences the prediction of surface erosion rates in technological applications that utilize these plasmas.

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Section: )mentioning

confidence: 97%

Section: Solutions On the Mean-free-path Scalementioning

confidence: 99%

Section: )mentioning

confidence: 99%

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