Electron Density and Gas Temperature from Line Broadening in an Argon Surface-Wave-Sustained Discharge at Atmospheric Pressure

Abstract

We have used the collisional broadening of neutral argon lines to determine the electron density and gas temperature of a microwave discharge at atmospheric pressure. The gas temperature can be obtained from the Van der Waals broadening, provided that the Stark broadening is negligible. This can be achieved by using lines from low-lying levels (close to the ground state). On the other hand, lines corresponding to transitions from high-lying levels, which are more sensitive to Stark (quadratic) broadening, can be utilized to determine electron density. The electron density values obtained from the quadratic Stark broadening of argon atoms are in reasonable agreement with those derived from the linear Stark broadening of the H(beta) line. The proposed method ensures perturbation-free access to plasma parameters, which is not the case when adding hydrogen to the discharge, even in a small amount, to observe the Balmer series lines.

Time resolved optical emission spectroscopy in power modulated atmospheric pressure plasma jet

“…The gas temperature is usually estimated from rotational temperature of some molecular species present in the discharge such as OH [24,[29][30][31][32], N 2 + [33,34], CN [35] or C 2 [36] on account of the highly favourable energy exchange between heavy particles and the internal rotationalvibrational states of the molecular species involved [37]. Assuming that admixture molecules are in equilibrium with the gas atoms majority, the rotational temperature (T rot ) derived from the ro-vibrational spectra can be considered equal to the gas temperature (T gas ) [28].…”

Using the van der Waals broadening of the spectral atomic lines to measure the gas temperature of an argon microwave plasma at atmospheric pressure

“…The gas temperature in plasmas is usually measured from the analysis of the rotational spectrum for molecular species present in the discharge, such as the OH species [9,10], N 2 + [11], CN [12] or C 2 [13]. These species stem from the water traces present as impurities in the carrier gas (OH) or when the plasma is in contact with the air impurities (N 2 + , CN and C 2 ).…”

Single channel atmospheric pressure transporting plasma and plasma stream demultiplexing: physical characterization and application toE. colibacteria inactivation

“…The gas temperature is usually obtained by means of the rotational temperature of some molecular species present in the discharge such as OH species [28][29][30] and N 2 + [31,32] on account of the highly favorable energy exchange of heavy particles and the internal rotational-vibrational states of the molecular species involved [33]. Assuming that these molecules are in equilibrium with the gas atoms, the rotational temperature derived from the rovibrational spectra can be considered as equal to the gas temperature.…”