https://doi.org/10.1051/epjap/2015140491
On the fundamental relation of laser schlieren deflectometry for temperature measurements in filamentary plasmas*
1
Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489, Greifswald, Germany
2
Department of Physical Electronics, Faculty of Science, Masaryk University, Kotláĭská 2, 61137, Brno, Czech Republic
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Received:
12
December
2014
Revised:
18
February
2015
Accepted:
26
February
2015
Published online:
15
July
2015
Abstract
Recently, laser schlieren deflectometry (LSD) had been successfully employed as a temperature measurement method to reveal the heat convection generated by micro filaments of a self-organized non-thermal atmospheric plasma jet. Based on the theory of the temperature measurements using LSD, in this work, three approaches for an application of the method are introduced: (i) a hyperbolic-like model of refractive index is applied which allows an analytical theory for the evaluation of the deflection angle to be developed, (ii) a Gaussian shape model for the filament temperature is implemented which is analyzed numerically and (iii) an experimental calibration of the laser deflection with a gas mixture of helium and argon is performed. Thus, these approaches demonstrate that a universal relation between the relative maximum temperature of the filament core (T1/T0) and a the maximum deflection angle δ1 of the laser beam can be written as T1/T0=(1 − δ1/δ0)−1, where δ0 is a parameter that is defined by the configuration of the experiment and by the assumed model for the shape of the temperature profile.
Contribution to the topical issue “The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)”, edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark
© The Author(s) 2015
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