Darmstadt 2008 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P II: Poster: Niedertemperaturplasmen, Plasmatechnologie

P II.19: Poster

Dienstag, 11. März 2008, 11:00–13:00, Poster C3

Dynamics of E to H Mode Transitions in Inductively Coupled Discharges — •Philipp Kempkes, Jan Tenfelde, and Henning Soltwisch — Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany

In order to investigate the dynamics of E to H mode transitions, they are periodically triggered via amplitude modulation of the discharge input power and a range of different diagnostic techniques, such as Langmuir probes, current and voltage probes and induction loop probes, is applied. Measurements are performed at high temporal resolution to match the ten-microsecond timescale the mode transitions typically occur on. We present the evolution of the electron energy distribution function (EEDF) during the E to H and the reverse H to E mode transition together with electrical characteristics and measurements of the rf magnetic field. The EEDF shows an enhanced low-energy part at the onset of both transitions, which is consistent with results, reported earlier [1,2]. The findings are compared to a time-resolved global model, which is supplemented by a semi-analytic calculation of the electromagnetic fields after Turner et. al. [3]. The results indicate that the power coupling efficiency between the power supply and the induction antenna changes considerably during the mode transitions, which might be a reason for the accompanying hysteresis effects, reported frequently.

[1] P. Kempkes et. al, Plasma Sources Sci. Technol. 15 (2006) 378-83

[2] S. V. Singh et. al, Appl. Phys. Lett. 89 (2006) 161501

[3] I. M. El-Fayoumi et. al, J. Phys. D: Appl. Phys. 31 (1998) 3082-94