Abdollah Sarani

The influence of water vapor content on electrical and spectral properties of an atmospheric pressure plasma jet

An atmospheric pressure plasma jet generated in Ar with water vapor is investigated. It is shown that an increase in the water content results in a decrease in the input power and asymmetry of the current waveform on positive and negative half-periods of the applied voltage. Space-resolved spectroscopy with a resolution of 1?mm and an imaging technique are applied for the characterization of the afterglow and investigation of the influence of water content on plasma properties. The rotational temperature of the jet is determined by simulation of the OH radical emission spectrum, transition A?2?+(v = 0) ? X?2?(v = 0). It is revealed that the temperature of the discharge increases from 450?K (Ar) up to 850?K with an increase in the water content up to 7600?ppm. Generation of the discharge in mixtures of argon with water vapor at a concentration of 350?ppm results in a maximal yield of OH radicals that can be useful in plasma jet applications. Preliminary tests of polypropylene surface modification are carried out in order to estimate the influence of water content on the results of treatment.

Characterization of Kilohertz-Ignited Nonthermal He and He/

In this paper, an atmospheric pressure low-temperature plasma pencil generated in helium and helium/ oxygen gas mixtures was characterized in detail for its discharge characteristics, plasma power, reactive plasma species produced, plasma density, and plasma temperatures using electrical and optical emission spectroscopy (OES) diagnostics, and its efficacy for biomedical application. A visible plasma plume length of approximately 27 mm was generated using a 60-kHz ac HV power supply. The OES results showed the most intensive plasma emission lines of OH transition A²Σ⁺(v = 0, 1)→X²Π(Δν = 0) at 308 nm and OH transition A²Σ⁺(v = 0, 1)→X²Π(Δν = 1) at 287 nm, O I transition 3p⁵P→3s⁵S⁰ at 777.41 nm, O I transition 3p³P→3s³S⁰ at 844.6 nm, and N₂(C-B) second positive system with electronic transition C³ Π_u→B³Π_g in the range 300-450 nm. The effects of controlled oxygen content on the plasma pencil and on various helium plasma emissions and electrical properties are studied. A spatial distribution of reactive plasma species produced by the plasma pencil is presented. The electron density of plasma jet was estimated to be in the order of 2.1 × 10¹⁴ cm^-3 using Stark broadening line profile of the hydrogen alpha emission. The temperatures of afterglow plasma pencil were evaluated using OH rotational temperatures, and the results demonstrate temperatures of 316 and 362 K for pure He and He/O₂ gas mixtures (0.1% O₂), respectively. Preliminary results on inactivation of Streptococcus pneumoniae on a solid surface and in liquid suspension were carried out using the plasma pencil for biomedical applications.

{\rm O}_{2}

Plasma jets have been proven to be an excellent source because of their several novel applications. However, little is known about the effect of adding water vapor to the feed gas. We investigated the dietetic barrier discharge plasma jet in pure helium and He/water-vapor mixture. This paper presents the plasma dynamics and its properties obtained by time-resolved imaging and results of emission spectra in both feed gases. Addition of water vapor results in a decrease of the jet plume length and an increase of OH radical intensity in emission spectra. Therefore, DBD plasma jet is an efficient source for OH radical production, where yield of radicals and plume length can be controlled by variation of water-vapor content in feed gas.