Physical interpretation of a pulsed atmospheric pressure plasma jet following parametric study of the UV–to–NIR emission

Physical interpretation of a pulsed atmospheric pressure plasma jet following parametric study of the UV–to–NIR emission

In the present report, an atmospheric pressure plasma jet is sustained in a helium channel by high square wave unipolar voltage. The gas flow rate and the square wave features (amplitude, frequency, and duty cycle) are varied over a wide range, while the plasma ultraviolet to near infrared emission...

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Bibliographic Details
Published in:Physics of plasmas 2020-12, Vol.27 (12)
Main Authors: Gazeli, K., Svarnas, P., Lazarou, C., Anastassiou, C., Georghiou, G. E., Papadopoulos, P. K., Clément, F.
Format: Article
Language:eng
Subjects:
Analytical chemistry
Atmospheric pressure
Chemical Sciences
Electric fields
Emission analysis
Engineering Sciences
Flow velocity
Gas flow
Gas temperature
Helium
Material chemistry
Near infrared radiation
Plasma
Plasma jets
Plasmas
Propagation
Pulse amplitude
Pulse duration
Pulse repetition rate
Square waves
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Summary:In the present report, an atmospheric pressure plasma jet is sustained in a helium channel by high square wave unipolar voltage. The gas flow rate and the square wave features (amplitude, frequency, and duty cycle) are varied over a wide range, while the plasma ultraviolet to near infrared emission is recorded. The plasma emission pattern, the propagation dynamics of the involved ionization fronts, the relative density of critical excited species, and the rotational and vibrational temperatures of neutral and ionic species are measured. An optimum operational window is found corresponding to a helium flow rate of 2 slm, a pulse amplitude of 7.5 kV, a pulse repetition rate of 10 kHz, and a pulse duty cycle of 5%–7%. Under these conditions, a plasma jet length close to 45 mm and a gas temperature close to 325 K are obtained, while a high yield of OH, N2(SPS), N 2 +(FNS), N2(FPS), He*, O*, and NOγ is achieved. The results are found to be in good agreement with the bibliography and motivate a consideration on the involved physical mechanisms. The plasma jet propagation with respect to the reactive species production is discussed based on the local electric field variation over the high voltage pulse width.
ISSN:1070-664X
1089-7674