Jena 2013 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

P: Fachverband Plasmaphysik

P 7: Niedertemperaturplasmen I

P 7.7: Fachvortrag

Dienstag, 26. Februar 2013, 18:15–18:40, HS 3

Mode transitions in low pressure discharges. — •Christian Küllig, Kristian Dittmann, Thomas Wegner, and Jürgen Meichsner — Institute of Physics, University of Greifswald, 17489 Greifswald

This contribution is addressed to mode transitions in inductively (ICRF) and capacitively coupled radio frequency (CCRF) discharges. In the CCRF oxygen discharge it is measured the transition from the α to γ-mode by means of spatio-temporal pattern of the excitation rates by means of PROES. Here an additional pattern appears by transition into the γ-mode, which is due to the secondary electron emission. Moreover, the transition is measured as changes in the line integrated electron and negative ion density as well as in its ratio (electronegativity), by means of microwave interferometry (MWI) and simultaneously laser photodetachment. Here the α to γ mode transition causes a change from a strongly high electronegative to low electronegative mode. Especially, this mode transition have strong influence on the temporal behaviour of the discharge, e.g., the afterglow behaviour. A different kind of mode transition will be presented for the ICRF discharge, the E to H mode transition, which is measured as change in the ion saturation current by means of Langmuir probe diagnostics (LPD) and the line integrated electron density by MWI. Moreover, the LPD reveals different spatially (axial, radial) resolved ion saturation current profiles for each mode. Especially the question of the appearance of a hysteresis is not yet clarified in literature and will also concern this contribution.// Funded by the DFG CRC/Transregio 24, project B5.