Thickness of the ion sheath around a cylindrical electrode in a plasma

Journal Article · Mon Apr 01 04:00:00 EST 1991 · IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/27.106841· OSTI ID:5689638

Nachman, M; Thanh, P C ^[1]

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1. Dept. of Electrical Engineering, Ecole Polytechnique, P.O. Box 6079, Station A, Montreal H3C 3A7 (CA)

In this paper the results of an experimental study of the thickness of the ion sheath set up at the interface between a cylindrical electrode and the plasma in which it is immersed are presented. A point-like, movable, electron-collecting cold probe is used for exploring the sheath region. The cylindrical electrode is biased negatively, and a low-frequency low-voltage ac signal is superimposed on this dc bias. The modulation of the electron density within the sheath, induced by this ac signal, manifests itself by a modulation in the current measured by the electron-collecting probe. The ac component of this current has a maximum peak value around the sheath-plasma boundary. The position of the point-like probe (relative to the cylindrical electrode) where the ac current is maximum is determined with a high degree of accuracy by means of a precision optical theodolite. Reliable data for the sheath thickness and its dependence on the absolute value of the applied dc bias could thus be obtained.

• OSTI ID: 5689638
• Journal Information: IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States), Journal Name: IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States) Vol. 19:2; ISSN 0093-3813; ISSN ITPSB
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
CHARGED PARTICLES
CONFIGURATION
CYLINDRICAL CONFIGURATION
DIMENSIONS
ELECTRODES
ELECTRON DENSITY
EQUIPMENT
INTERFACES
IONS
OPTICAL EQUIPMENT
PLASMA
PLASMA DIAGNOSTICS
PLASMA SHEATH
THICKNESS