The Bohm Criterion for Radiofrequency Discharges - a Numerical Verification Based on Poisson Equation

TitleThe Bohm Criterion for Radiofrequency Discharges - a Numerical Verification Based on Poisson Equation
Publication TypeJournal Article
Year of Publication1993
AuthorsP.M Meijer, W.J Goedheer
JournalPhysics of Fluids B-Plasma Physics
Volume5
Number5
Pagination1656-1660
Date PublishedMay
ISBN Number0899-8221
Abstract

Recently it was shown that, by using the analysis of electrostatic waves entering the plasma-sheath edge, the direct-current (dc) Bohm criterion also holds for discharges under radio-frequency (rf) conditions. In this paper, the influence of Bohm's criterion on the sheath characteristics for generator frequencies much higher than the ion plasma frequency has been examined by means of an analysis which is based directly on the numerical solution of the Poisson equation. The present calculations indicate that for high rf voltages the time-dependent potential profile does not always increase monotonically, even if Bohm's criterion is fulfilled. However, as this nonmonotonic behavior does not lead to a more stringent Bohm criterion, the statement that the original dc Bohm criterion also holds in the high-frequency regime is confirmed. The calculations show further that the time-dependent sheath potential is almost completely modulated in the major part of the sheath and that the modulation drops abruptly to zero close to the plasma-sheath edge.

DOI10.1063/1.860798
PID

0d0ca6e27bdde72a9b55f6382bfd5295

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