UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2009 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
Small Size Dielectric Barrier Discharges at atmospheric pressure and their characterization


Authors:
M. Teodorescu*, E. R. Ionita*, C. Stancu*, M. Bazavan**, G. Dinescu*


Affiliation:
* National Institute for Lasers, Plasma and Radiation Physics, Magurele - Bucharest, Romania

** University of Bucharest, Faculty of Physics PO Box MG 11, 077125 Magurele, Romania


E-mail
maximilian.teodorescu@infim.ro


Keywords:
dielectric barrier, cold plasma, treatment


Abstract:
The development of new types of atmospheric pressure plasma sources is necessary for plasma processing of materials, and other industrial or commercial applications. One of the advantages of Dielectric Barrier Discharges (DBD’s) is that their plasma has a relatively low temperature even at atmospheric pressure, and thus makes them attractive for processing materials which are sensitive to thermal damage, like polymers or biological samples. In this contribution radiofrequency plasma sources based on discharges limited by dielectric barriers with different electrode configurations are presented. The examined designs focus on rectangular discharge geometries, with one or two dielectric barriers, and electrode spacing of 1 to 2 mm. By fast flowing the gas through the discharge gap, a plasma expanding outside the gap, with a two dimensional geometry, is obtained. The dimension of the plasma along the flowing direction is of 3 to 6 mm and is controlled by the decaying phenomena. The length of the plasma in another direction is determined by the device geometry. The operating domains of the plasma sources, i.e. expanding plasma dependences on flow rate, RF power, voltage, were investigated. The plasma characteristics in these sources were also examined by different measurement methods including OES, electrical measurements, and imaging techniques. The Optical Emission Spectroscopy was carried out using a medium to high resolution Spectrometer. For the actual measurements we have selected two distinct spectral regions, one centred on the OH 3064 Å system, and one comprising the Argon lines in the 600 – 1000 nm region. By fitting the experimental spectra corresponding to OH bands with the simulated ones, the rotational temperature along the expansion plane was determined. The obtained values prove the cold character of the plasma. The devices were tested as tools for modification of wetability of polymer surfaces.