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P: Fachverband Plasmaphysik

P 2: Diagnostics

P 2.7: Vortrag

Montag, 8. März 2010, 15:40–15:55, B 305

Electron density measurements of an inductive coupled plasma with a one port microwave interferometer — •Mathias Andrasch, Jörg Ehlbeck, Jens Harhausen, Rüdiger Foest, and Klaus-Dieter Weltmann — Leibniz-Institut für Plasmaforschung und Technologie e.V.

The electron density is one of the fundamental parameters of non equilibrium plasmas. A standard microwave interferometer method is the two port measurement, which requires two accessible windows in the reactor. Most industrial plasma reactors, however, have only one accessible window, thus favoring a one port microwave interferometer method where a microwave mirror is placed at the opposite side of the reactor wall. The interferometer works at 45.5 GHz and separates the forwarded and the reflected wave. With this system the line integrated electron densities in an inductive coupled plasma (13.56 MHz) (Ar, N₂, 0.2-8.0 Pa, 30-1000 W) are determined. Langmuir probe measurements provide the radial profile of the electron density. These profiles are fitted with Bessel functions and serve for the determination of spatially resolved density values from the microwave interferometric measurements. The densities are in good agreement with the Langmuir probe results. Maximum values 1·10¹⁸ m⁻³ are obtained in the center of the vessel at an axial distance of 0.24 m from the antenna window of the ICP source. (Partially Funded by BMBF, FKZ: 13N9320)