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Title: A radio-frequency sheath model for complex waveforms

Plasma sheaths driven by radio-frequency voltages occur in contexts ranging from plasma processing to magnetically confined fusion experiments. An analytical understanding of such sheaths is therefore important, both intrinsically and as an element in more elaborate theoretical structures. Radio-frequency sheaths are commonly excited by highly anharmonic waveforms, but no analytical model exists for this general case. We present a mathematically simple sheath model that is in good agreement with earlier models for single frequency excitation, yet can be solved for arbitrary excitation waveforms. As examples, we discuss dual-frequency and pulse-like waveforms. The model employs the ansatz that the time-averaged electron density is a constant fraction of the ion density. In the cases we discuss, the error introduced by this approximation is small, and in general it can be quantified through an internal consistency condition of the model. This simple and accurate model is likely to have wide application.
Authors:
 [1] ;  [2]
  1. School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)
  2. Laboratoire de Physique des Plasmas, Centre National de la Recherche Scientifique, Ecole Polytechnique, Université Pierre et Marie Curie, Paris XI, 91128 Palaiseau (France)
Publication Date:
OSTI Identifier:
22262582
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRON DENSITY; EXCITATION; PLASMA SHEATH; RADIOWAVE RADIATION; WAVE FORMS