Study of laser mixture in glow discharge at low and middle pressures in silica and pyrex discharge tubes

Abstract

The positive column of the DC glow discharge sustained in CO 2 laser mixture (containing CO 2 , N 2 and He at the ratio of 6:24:70) has been studied in pressure range 130÷1350 Pa and for discharge currents in range 10 ÷ 50 mA in two discharge tubes of the same shape, made from two different materials. Our main goal was the study of spectra by means of optical emission spectroscopy. We have focused on the investigation of intensities of spectral bands of the second positive system of molecular nitrogen corresponding to the transitions C 3 Π→B 3 Π and Angström band of CO molecules (transitions B 1 Σ→A 1 Π) in reference to important role of this molecules in the discharge. It has been found that intensity of nitrogen bands decreases with increasing pressure and with decreasing current. It was possible to estimate vibrational temperature T vib from measured intensities of above -mentioned bands of molecular nitrogen. It was observed that T vib increases with increasing discharge current and slightly decreases with increasing pressure.The other result of our measurement was fact that intensity of Angström band of CO molecules decreases with increasing pressure and increases with increasing current. No significant role of the material of the discharge tubes was found.