Fulfillment of the kinetic Bohm criterion in a quasineutral particle-in-cell model

Eduardo Ahedo, Robert Santos, F́lix I. Parra

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19 Scopus citations

Abstract

Quasineutral particle-in-cell models of ions must fulfill the kinetic Bohm criterion, in its inequality form, at the domain boundary in order to match correctly with solutions of the Debye sheaths tied to the walls. The simple, fluid form of the Bohm criterion is shown to be a bad approximation of the exact, kinetic form when the ion velocity distribution function has a significant dispersion and involves different charge numbers. The fulfillment of the Bohm criterion is measured by a weighting algorithm at the boundary, but linear weighting algorithms have difficulties to reproduce the nonlinear behavior around the sheath edge. A surface weighting algorithm with an extended temporal weighting is proposed and shown to behave better than the standard volumetric weighting. Still, this must be supplemented by a forcing algorithm of the kinetic Bohm criterion. This postulates a small potential fall in a supplementary, thin, transition layer. The electron-wall interaction is shown to be of little relevance in the fulfillment of the Bohm criterion.

Original languageEnglish (US)
Article number073507
JournalPhysics of Plasmas
Volume17
Issue number7
DOIs
StatePublished - Jul 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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