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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:57 |
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Conference: Bucharest University Faculty of Physics 2021 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
The use of optical emission spectroscopy in the
study of a filamentary argon plasma jet
Authors:
Catalin CONSTANTIN (1), Ciprian DUMITRACHE (1), Bogdana MITU (1)
Affiliation:
1) INFLPR
E-mail
catalin.constantin@inflpr.ro
Keywords:
RF-plasma jet, Optical Emission Spectroscopy, Plasma Diagnostics
Abstract:
A stable argon plasma jet discharged in ambient air is spectrally characterized herein. The plasma is sustained inside a glass tube with an internal diameter of 4 mm using a radio-frequency generator operating at 100 W and 13.56 MHz. An interesting regime is observed when the discharge is operated with only one external electrode on the tube and in the absence of any grounded electrode in discharge proximity (floating ground). In such a configuration, the plasma jet develops two distinct regions: a filamentary-like (high electron density) core and a surrounding diffuse zone where emission comes mainly from excited molecular nitrogen[1]. As such, in this study we focus our attention on the plasma jet generated at 3000 sccm Ar exiting the tube. The jet has a length of ~40 mm and is the result of the mixing of the argon plasma with the surrounding air.
The study includes spatially resolved measurements of electron number density obtained from Stark broadening analysis performed on the Hα (656 nm) and Hβ (486 nm) lines [2]. In order to separate the hydrogen lines from the background molecular nitrogen emission (primarily N2 (B-A)), a small amount of H2 (1 sccm) was used for post processing the Stark broadening data. It was shown previously that H2 tends to raise the plasma temperature through the generation and dissociation of the ArH radical [3]. To ensure that H2 addition does not alter the properties of our plasma jet, we verified that N2(SPS) spectra at 380nm (v = -2) is identical with and without H2 injection. This is an important point as the N2(SPS) is primarily generated through electron impact reactions with ground state N2. Therefore, the fitted rotational temperature from the N2(SPS) spectrum is indicative of the actual gas temperature[4].
References:
[1] Teodorescu M, Bazavan M, Ionita E R, Dinescu G 2015 Plasma Sources Sci. Technol. 24 025033
[2] Laux C O, Spence T G, Kruger C H and Zare R N 2003 Optical diagnostics of atmospheric pressure air plasmas Plasma Sources Sci. Technol. 12 125–38
[3] Bogaerts A 2002 Hydrogen addition to an argon glow discharge: A numerical simulation J. Anal. At. Spectrom. 17 768–79
[4] Rusterholtz D L, Lacoste D A, Stancu G D, Pai D Z and Laux C O 2013 Ultrafast heating and oxygen dissociation in atmospheric pressure air by nanosecond repetitively pulsed discharges J. Phys. D. Appl. Phys. 46 464010
Acknowledgement:
I wish to extend my special thanks to: Dumitrache Ciprian, Mitu Bogdana and Dinescu Gheorghe.
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