Diagnostics of atmospheric-pressure pulsed-dc discharge with metal and liquid anodes by multiple laser-aided methods. (26th May 2016)

• Record Type: Journal Article
• Authors: Urabe, Keiichiro; Shirai, Naoki; Tomita, Kentaro; Akiyama, Tsuyoshi; Murakami, Tomoyuki
• Is Part Of: Plasma sources science & technology. Volume 25:Number 4(2016:Aug.)
• Publication Date: 2016-05-26
• Subjects: atmospheric-pressure plasma -- laser diagnostics -- plasma in contact with liquid -- electron density -- electron temperature -- excited species density; Plasma (Ionized gases) -- Periodicals; 530.44
• DOI: 10.1088/0963-0252/25/4/045004
• Languages: English
• ISSNs: 0963-0252

Abstract

Abstract: The density and temperature of electrons and key heavy particles were measured in an atmospheric-pressure pulsed-dc helium discharge plasma with a nitrogen molecular impurity generated using system with a liquid or metal anode and a metal cathode. To obtain these parameters, we conducted experiments using several laser-aided methods: Thomson scattering spectroscopy to obtain the spatial profiles of electron density and temperature, Raman scattering spectroscopy to obtain the neutral molecular nitrogen rotational temperature, phase-modulated dispersion interferometry to determine the temporal variation of the electron density, and time-resolved laser absorption spectroscopy to analyze the temporal variation of the helium metastable atom density. The electron density and temperature measured by Thomson scattering varied from 2.4 × 10 14 cm −3 and 1.8 eV at the center of the discharge to 0.8 × 10 14 cm −3 and 1.5 eV near the outer edge of the plasma in the case of the metal anode, respectively. The electron density obtained with the liquid anode was approximately 20% smaller than that obtained with the metal anode, while the electron temperature was not significantly affected by the anode material. The molecular nitrogen rotational temperatures were 1200 K with the metal anode and 1650 K with the liquid anode at the outer edge of the plasma column. The density of helium metastable atoms decreased by a factor of two when using the liquid anode.