Effect of plasma on gas flow and air concentration in the effluent of a pulsed cold atmospheric pressure helium plasma jet

E. R.W. Van Doremaele, V. S.S.K. Kondeti, P. J. Bruggeman

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

In this work, we report on the flow effects induced by a nanosecond pulsed helium cold atmospheric pressure plasma jet impinging on a glass substrate. Gas temperature measurements have been performed using optical emission spectroscopy including rotational spectra of OH(A-X) (0,0) and N2(C-B) (0,0) and resonance broadening of a helium emission line at 667.8 nm. The measured increase in gas temperature was less than 15 K. We have measured the air concentration distribution in the jet effluent by means of Rayleigh scattering exploiting the large difference in Rayleigh cross-section of air and helium. The obtained results show that the plasma causes a broadening of the helium channel suggesting an enhanced gas velocity and mixing with the ambient air. The impact of the plasma on the jet effluent is polarity dependent and is larger in the case of positive applied voltage pulses. Using an estimation of the increased gas velocity required to obtain the observed air concentrations, we have shown that both gas heating and electrohydrodynamic (EHD) forces related to the propagation of an ionization front are not causing the observed phenomena. The surface charge which can exist for a much longer time than the duration of the applied voltage pulse is the primary cause of the EHD forces on the bulk charges which lead to significant different air concentration profiles in the jet effluent for plasma on and off.

Original languageEnglish (US)
Article number095006
JournalPlasma Sources Science and Technology
Volume27
Issue number9
DOIs
StatePublished - Sep 14 2018

Bibliographical note

Funding Information:
The research has been supported by the Department of Energy, Office of Fusion Energy Sciences (DE-SC0016053).

Publisher Copyright:
© 2018 IOP Publishing Ltd.

Keywords

  • Rayleigh scattering
  • Schlieren imaging
  • air admixing
  • atmospheric pressure plasma jet
  • ionic wind
  • plasma-flow interactions
  • space charge

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