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Progress in Plasma Processing of Materials, 1999

ISBN:
1-56700-126-2 (Print)

IDENTIFICATION OF LOCAL AND GLOBAL OSCILLATIONS IN A PLAS~A JET

J. Hlina
Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Praha 8, Czech Republic

V. Nenicka
Institute of Electrical Engineering, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 02 Praha 8, Czech Republic

Abstract

Oscillations of an argon plasma jet detected optically outside the arc chamber were compared with those found in the records of the arc voltage and analyzed using the fast Fourier transform. The resulting frequency spectra show significant differences in occurence of some oscillations inside and outside the arc chamber depending on the gas flow rate. The global oscillations generated especially at high gas flow rates show also remarkable deviations when the differences of the phase angles related to two points situated at different positions along the flow are evaluated.