Greifswald 2009 – scientific programme
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P: Fachverband Plasmaphysik
P 15: Poster: Diagnostik
P 15.12: Poster
Wednesday, April 1, 2009, 17:30–19:30, Foyer des IfP
Formation of microplasmas in small capillaries — •Sarah Panowitz1,2, Jakob Barz2, Michael Müller2, Joachim Franzke3, and Christian Oehr2 — 1IGVT, Uni Stuttgart — 2Fraunhofer IGB, Stuttgart — 3ISAS- Institute for Analytical Sciences, Dortmund
The surface modification of small and narrow volumes, like capillaries, for chemical and medical applications using plasma glow discharges is still a challenge. By plasma generation inside these small volumes, it is possible to coat or to clean their inner surfaces or to functionalize them with different chemical groups. Realizing a glow discharge in these volumes crucially depends on the geometry and the pressure in the experimental setup. We investigated plasma formation in capillaries made of glass or different polymers with diameters between 250 µ m and 5 mm in a pressure range of several mbar.
To characterize the plasma, it was analyzed by optical emission spectroscopy (OES) and temperature measurements. The optical emission properties are correlated with the temperature on the outer side of the quartz capillary. There are different methods to determine electron-temperature, electron density or gas temperature from optical emission. From line intensities it is possible to determine the rotational temperature of N2+, which is assumed to be the same as the neutral gas temperature. By investigating the interaction of pressure, frequency, and power, it was found that for low plasma gas temperatures, the kHz-region is a good choice. Furthermore, it is necessary to work in the minimum of the Paschen-curve.