Comment on 'Sheath model for dual-frequency capacitive discharges'. (8th July 2015)

• Record Type: Journal Article
• Authors: Chen, Wen-Cong; Pu, Yi-Kang
• Is Part Of: Journal of physics. Volume 48:Number 26(2015)
• Page Start: 697
• Publication Date: 2015-07-08
• Subjects: Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/26/268001
• Languages: English
• ISSNs: 0022-3727

Abstract

<abstract> <title>Abstract</title> <p>Boyle <italic>et al</italic> (2004 <italic>J. Phys. D: Appl. Phys.</italic><bold>37</bold> 1451) introduced a sheath model for dual-frequency capacitive discharges. The electron sheath edge position <italic>s</italic> and the dc potential Φ_dc in the sheath are obtained with the assumption <italic>α/β</italic> &gt;&gt; 1 (where <italic>α/β</italic> is the ratio of the low-frequency electric field to the high-frequency electric field). However, <italic>α/β</italic> ≤ 4 is usually found in processing applications. Under this condition, we show that the Boyle <italic>et al</italic> model gives multiple values for the dc potential Φ_dc(<italic>x</italic>) at any given position <italic>x</italic> in the sheath. For this reason, we introduce a model without the assumption <italic>α</italic>/<italic>β</italic> &gt;&gt; 1. By comparing the results from the two models, it is found that, as the ratio <italic>α</italic>/<italic>β</italic> approaches 1, the sheath thickness <italic>s</italic>_m and the sheath dc voltage <italic>V</italic>_dc obtained with the Boyle <italic>et al</italic> model are significantly underestimated.</p> </abstract>