Spectroscopic investigation of non-thermal plasma generated in atmospheric pressure ‘Plasma Pencil’

Abstract

Plasma generated at atmospheric pressure has widespread applications in the field of plasma medicine. In this paper, spectroscopic investigations of homemade capacitively coupled, atmospheric pressure RF plasma pencil is reported. Optical emission spectroscopy (OES) technique is employed to characterize the plasma. Variation in rotational/gas temperature [Formula: see text], [Formula: see text] atomic density, dissociation fraction [Formula: see text] and normalized intensities of [Formula: see text], [Formula: see text] and [Formula: see text] radiation is monitored as a function of discharge parameters like RF power and different gases concentration. [Formula: see text] of [Formula: see text] mixture is estimated from [Formula: see text] band head of R branch of first negative system of nitrogen [Formula: see text], [Formula: see text], [Formula: see text] using Boltzmann plot technique. Similarly, [Formula: see text] band head of second positive system (SPS) of nitrogen [Formula: see text], [Formula: see text], [Formula: see text] is also used to estimate [Formula: see text] by fitting synthetic spectra over the experimentally recorded spectrum. It is noted that [Formula: see text] increases with increase in RF power, but it decreases with increase in [Formula: see text] concentration in the mixture. [Formula: see text] atomic density and dissociation fraction [Formula: see text], estimated from [Formula: see text] line at 750 nm and [Formula: see text] line at 844 nm using actinometry technique, show increasing trend with RF power and [Formula: see text] concentration in the mixture up to 0.7% [Formula: see text] in the mixture. The normalized [Formula: see text] radiation intensities; [Formula: see text], [Formula: see text] and [Formula: see text] show the increasing trend with increase in RF power up to 0.3% [Formula: see text] concentration in the mixture.