Excitation and dissociation of CO2 heavily diluted in noble gas atmospheric pressure plasma

Stewig, C. and Schüttler, S. and Urbanietz, T. and Böke, M. and Von Keudell, A.

Volume: 53 Pages:
DOI: 10.1088/1361-6463/ab634f
Published: 2020

The excitation and dissociation of CO2 admixed to argon and helium atmospheric pressure radio frequency plasmas is analyzed. The absorbed plasma power is determined by voltage and current probe measurements and the excitation and dissociation of CO2 and CO by transmission mode Fourier-transform infrared spectroscopy (FTIR). It is shown, that the vibrational temperatures of CO2 and CO are significantly higher in an argon compared to a helium plasma. The rotational temperatures remain in both cases close to room temperature. The conversion efficiency, expressed as a critical plasma power to reach almost complete depletion, is four times higher in the argon case. This is explained by the lower threshold for the generation of energetic particles (electrons or metastables) in argon as the main reactive collision partner, promoting excitation and dissociation of CO2, by the less efficient quenching of vibrational excited states of CO and CO2 by argon compared to helium and by a possible contribution of more energetic electrons in an argon plasma compared to helium. © 2020 IOP Publishing Ltd.

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