Generation of cold atmospheric plasma jet by a coaxial double dielectric barrier reactor

Abstract

In this study, the generation of cold atmospheric plasma jet was investigated in a coaxial double dielectric barrier configuration conjugated with a microsecond voltage pulse generator. The advanced reactor comprised two coaxial dielectric tubes of different diameters with two ringshaped electrodes covering outside the larger tube. The electrodes were immersed in a liquid dielectric (i.e. transformer oil) in order to isolate them from the ambient air, which completely prevented the direct sparks formation between them within the investigated range of the applied voltage. The He discharge gas was fed to the inner tube while either air, N 2 , or O 2 as a shielding gas was introduced into the gap between the two dielectrics. The result revealed that with these shielding gases, the unwanted abnormal discharge in the inter-dielectric gap was extinguished and the plasma discharge occurred only in the He gas in the inner tube. Consequently, the electrical power delivered to the He discharges maintained at a level of around 1 W with a considerable variation in the applied voltage. Meanwhile, the discharge power of the unshielded jet was almost tripled as the applied voltage was increased from 7 to 10 kV. Interestingly, the cold plasma jet generated by the alternative reactor design in this study, which had the electron density up to 2.5 × 10 13 cm −3 , consumed relatively less He gas with less restriction on the high voltage range applied. The design also enhanced the possibility to control the plasma chemistry and jet temperature by changing the shielding gas. Therefore, the reactor is capable of producing a cold atmospheric plasma jet for the emerging plasma application such as plasma medicine and bio-applications.

Transmission and multiple reflection mechanisms of guided streamers propagating through grounded annular electrode and interacting with grounded surface electrode

“…Such APPJ present double dielectric barriers as sketched in the (a) configuration where two outer rings surround a dielectric capillary, in the (b) configuration where a pin electrode is embedded in a dielectric material or in the (c) configuration where the polarized electrode and the counter-electrode are wounded around a tube following a double helix structure. Such dielectric-embedded electrodes are particularly relevant for processing liquids or corrosive gases [11]. The second category corresponds to the APPJ's with single-dielectric barrier so that plasma is in contact with only one electrode.…”

Transparent Polyaniline Thin Film Synthesized Using a Low-Voltage-Driven Atmospheric Pressure Plasma Reactor

“…In general, APPJs have a simple structure consisting of a gas-feeding tube and electrodes. To prevent the unwanted transition of glow to arc discharge, a dielectric barrier that can easily control the current during discharge is commonly used, thus resulting in AC discharge [ 19 , 20 , 21 , 22 , 23 ]. When generating a DC discharge, it is common to expose the powered electrode to the discharge space, include a proper ballast resistor in the circuit to control the current, and ground the counter electrode [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ].…”

The influences of shielding gas and quartz tube on discharge properties and reactive species productions of nanosecond pulsed gas–liquid discharge

“…R15 [42] excitations R1-R4, see table 1), and He * are produced by electron impacted excitations (R5) [15,17,39]. While the excited state N 2 + (B) with 18.7 eV excitation energy, can be produced by the Penning ionization process between metastable He * (19.8 ∼ 23.7 eV) and molecule N 2 (R6) [40,41].…”

“…Recently, one method has proposed that using shielding gas flow to limit air diffusion into the discharge region, and help to stabilize and control plasma propagation as well as reactive species production [12][13][14][15]. For example, Yatom et al combined experimental and computational investigations to conclude that shielding Ar gas in the discharge configuration decrease the air diffusion into the discharge region, which can significantly increase electron density and the ionization of water in wet gas discharge [13].…”