Rotational temperature of oxygen molecules in DC glow discharge in O2–Ar mixtures sustained in discharge tube made from Pyrex glass

The active DC glow discharge sustained in pure O2 and O2–Ar mixtures with Ar/O2 concentration ratios up to 50% has been studied in a Pyrex discharge tube for pressures up to 500 Pa and for discharge currents up to 40 mA. The electric field strength and emission spectra parameters of the discharge were studied by means of the double-probe method and optical emission spectroscopy.The electric field strength was found to increase with the pressure and decrease with the discharge current, which is typical for DC glow discharges. Considering O2–Ar mixtures, the values of electric field strength decreased with Ar/O2 ratio.We have focused on the emitted radiation. The rotational temperature Trot of molecular oxygen was determined from the well-resolved atmospheric A-band at 760 nm. The increase of the rotational temperature with increasing deposited power has been observed for all studied Ar/O2 ratios. Moreover, it has been found that values of Trot are independent of the mixture composition.