Original Paper

Plasma Chemistry and Plasma Processing

, Volume 30, Issue 5, pp 537-552

Electrical, Thermal and Optical Diagnostics of an Atmospheric Plasma Jet System

  • C. E. NwankireAffiliated withSchool of Mechanical and Materials Engineering, University College Dublin Email author 
  • , V. J. LawAffiliated withNational Centre for Plasma Science and Technology, Dublin City University
  • , A. NindrayogAffiliated withCentre for Plasma Physics, Department of Physics and Astronomy, Queen’s University Belfast
  • , B. TwomeyAffiliated withSchool of Mechanical and Materials Engineering, University College Dublin
  • , K. NiemiAffiliated withCentre for Plasma Physics, Department of Physics and Astronomy, Queen’s University Belfast
  • , V. MilosavljevićAffiliated withNational Centre for Plasma Science and Technology, Dublin City UniversityFaculty of Physics, University of Belgrade
  • , W. G. GrahamAffiliated withCentre for Plasma Physics, Department of Physics and Astronomy, Queen’s University Belfast
  • , D. P. DowlingAffiliated withSchool of Mechanical and Materials Engineering, University College Dublin Email author 

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Abstract

Plasma diagnostics of atmospheric plasmas is a key tool in helping to understand processing performance issues. This paper presents an electrical, optical and thermographic imaging study of the PlasmaStream atmospheric plasma jet system. The system was found to exhibit three operating modes; one constricted/localized plasma and two extended volume plasmas. At low power and helium flows the plasma is localized at the electrodes and has the electrical properties of a corona/filamentary discharge with electrical chaotic temporal structure. With increasing discharge power and helium flow the plasma expands into the volume of the tube, becoming regular and homogeneous in appearance. Emission spectra show evidence of atomic oxygen, nitric oxide and the hydroxyl radical production. Plasma activated gas temperature deduced from the rotational temperature of nitrogen molecules was found to be of order of 400 K: whereas thermographic imaging of the quartz tube yielded surface temperatures between 319 and 347 K.

Keywords

Plasma jet Diagnostics Plasma diagnostics Optical emission Infrared thermography Corona