Darmstadt 2008 – scientific programme

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P: Fachverband Plasmaphysik

P II: Poster: Niedertemperaturplasmen, Plasmatechnologie

P II.9: Poster

Tuesday, March 11, 2008, 11:00–13:00, Poster C3

Langmuir probe measurements in an inductively coupled radio frequency plasma — •Yusuf Celik, Beilei Du, Dirk Luggenhölscher, and Uwe Czarnetzki — Institute for Plasma and Atomic Physics, Ruhr University Bochum, 44780 Bochum, Germany

Langmuir probe measurements in an inductively coupled radio frequency plasma in a modified GEC cell in argon and in hydrogen were performed. A double spiral three turn antenna embedded in a quartz cylinder replaces the standard GEC antenna. The electron energy distribution function (EEDF) is inferred via the Druyvesteyn method. Radial profiles of the mean energy and the density of electrons at various pressures and input powers were obtained. The toruslike structure of the poloidal electrical field induced by the antenna is recovered in the energy profiles whereas the density profiles illustrate a Bessel shape.

Furthermore, the variation of the plasma parameter with the exposure time, when a voltage to the probe tip is applied, is shown in order to investigate the perturbation of the plasma by the probe. The plasma potential and the mean energy of electrons increase by increasing the exposure time from 100 microseconds to 100 milliseconds while the density decreases.

Radial scans of the EEDF allow calculating the spatial distribution of the Balmer-α emission in hydrogen using a corona model. The calculations show a very good agreement with results obtained by a novel optical probe for spatially resolved emission spectroscopy.