Berlin 2001 – scientific programme

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P: Plasmaphysik

P 11: Dusty Plasmas and Low Temperature Discharges (Poster Session)

P 11.6: Poster

Thursday, April 5, 2001, 12:30–15:00, AT2

Langmuir Probe Measurements in Inductively Coupled Argon- and Hydrogen Plasmas — •V. Schulz-von der Gathen, Y. Lokurlu, and H.F. Döbele — Universität Essen, Institut für Laser- und Plasmaphysik, Universitätsstr. 5, 45117 Essen

We present Langmuir probe measurements in an inductively coupled RF-discharge. The transceiver power of between 25 and 300 W at 13.56 MHz is coupled to the plasma through a dielectric window via a plane coil with 80 mm diameter and 4 turns. The free distance from the window to the grounded electrode is 25 mm. Hydrogen with a 1 % admixture of argon and pure argon are used. The base pressure is varied between 5 and 30 Pa. The distortion of the passively compensated probe system by the base RF frequency and its higher orders was checked by a FFT analysis. The probe was installed radially into the discharge vessel.

We investigated the variations of the electron energy probability function EEPF), the electron density and the effective temperature as function of gas pressure and applied power for both gases. There are clear differences in the discharge behaviour for the molecular and atomic medium. Furthermore, we present and discuss radial profiles of the EEPF, electron density and temperature and plasma potential. Dependences on the mean free path are clearly observed.

This work was supported by the DFG in the frame of the SFB 191.