Darmstadt 2008 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P IV: Poster: Niedertemperaturplasmen II, Astrophysikalische Plasmen, Magnetischer Einschluss, Plasma-Wand-Wechselwirkung
P IV.14: Poster
Donnerstag, 13. März 2008, 16:00–18:30, Poster C2
Plasma structures caused by local rf activation of the passive electrode — •Florian Sigeneger1, Ralf Basner1, Detlef Loffhagen1, and Holger Kersten2 — 1INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald — 2IEAP, Christian-Albrechts-Universität, 24098 Kiel
In the plasma sheath of a passive electrode of a capacitively coupled rf discharge, the rf modulation of the potential is normally much lower than the period averaged voltage. In this case, the width of the sheath and the spatial density profiles of charge carriers are only slightly modified by changing the dc voltage of the passive electrode. However, an additional local supply of rf power at the passive electrode leads to strongly modified sheath structures. This effect has been investigated by means of the reactor PULVA-INP. The central pixel of its adaptive electrode was driven by an additional rf voltage. The pronounced change of the potential was demonstrated by the sensitive response of microparticles in the sheath. Furthermore, a large enhancement of the local power density becomes obvious from the strong enlargement of the light emission in front of the pixel. The investigations are supplemented by fluid modelling of the argon plasma in the reactor. The model comprises particle balance equations of electrons and ions, Poisson's equation and the electron energy balance equation. The results of the model calculations demonstrate the structural change of the potential and the local increase of the electron density and power density in front of the central pixel. The strongly increased excitation rate corresponds to the observed enlargement of the light emission.