Volume 66, Number 2, April 2004
|Page(s)||232 - 238|
|Section||Physics of gases, plasmas and electric discharges|
|Published online||01 April 2004|
Spectroscopic measurements of phase-resolved electron energy distribution functions in RF-excited discharges
Ruhr-Universität Bochum, Institut für Plasma- und Atomphysik 44780 Bochum, Germany (Present address.)
2 Universität Duisburg-Essen, Institut für Laser- und Plasmaphysik 45117 Essen, Germany
Corresponding author: Timo.Gans@web.de
Accepted: 6 February 2004
The reliable measurement of the electron energy distribution function (EEDF) of plasmas is one of the most important subjects of plasma diagnostics, because this piece of information is the key to understand basic discharge mechanisms. Specific problems arise in the case of RF-excited plasmas, since the properties of electrons are subject to changes on a nanosecond time scale and show pronounced spatial anisotropy. We report on a novel spectroscopic method for phase- and space-resolved measurements of the electron energy distribution function of energetic () electrons in RF discharges. These electrons dominate excitation and ionization processes and are therefore of particular interest. The technique is based on time-dependent measurements during the RF cycle of excited-state populations of rare gases admixed in small fractions. These measurements yield —in combination with an analytical model— detailed information on the excitation processes. Phase-resolved optical emission spectroscopy allows us to overcome the difficulties connected with the very low densities (107–109) and the transient character of the electrons in the sheath region. The EEDF of electrons accelerated in the sheath region can be described by a shifted Maxwellian with a drift velocity component in direction of the electric field. The method yields the high-energy tail of the EEDF on an absolute scale. The applicability of the method is demonstrated at a capacitively coupled RF discharge in hydrogen.
PACS: 52.70.-m – Plasma diagnostic techniques and instrumentation / 52.70.Kz – Optical (ultraviolet, visible, infrared) measurements / 52.80.Pi – High-frequency and RF discharges
© EDP Sciences, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.