A two-coupled-sheath model for the conduction of current through asymmetric parallel plate RF discharges

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Bulletin of the American Physical Society

OSTI ID:127907

Sato, A H; Lieberman, M A ^[1]

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1. Univ. of California, Berkeley, CA (United States)

The effect of electrode area ratio on the current flowing through a parallel plate rf discharge is studied to gain qualitative understanding on how current continuity is maintained in asymmetric systems and how electrode asymmetry affects the harmonic spectrum of the current. A uniform ion density sheath model is used. The total current flowing through the powered electrode sheath is equated to that at the ground electrode sheath, and the external voltage is set equal to the sum of the voltage drops across each sheath. This results in a first order differential equation in one sheath voltage, which is integrated numerically. Some results are: (1) The current waveforms approach skewed sine waves with increasing rf amplitude. (2) Current continuity is accomplished by nonsinusoidal variations in the sheath voltages. (3) Increasing the area ratio induces a broadening of both conduction and displacement current frequency spectra. (4) At modest area ratios, the large, distinct conduction current spike is very weak. In this case, the coupling of two sheaths allows nonsinusoidal variations in the sheath voltages that broaden the conduction current wave form.

• DOE Contract Number: FG03-87ER13727
• OSTI ID: 127907
• Report Number(s): CONF-920376--; CNN: Grant ECS-8517363
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 37; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ELECTRIC CURRENTS
HARMONICS
HIGH-FREQUENCY DISCHARGES
MATHEMATICAL MODELS
PLASMA SHEATH