Langmuir Probe and Optical Emission Spectroscopy Studies of Low-Pressure Gas Mixture of CO₂and N₂

Optical emission spectroscopy was used to study a gas mixture glow discharge of CO 2 and N 2 at a total pressure of 1.2 Torr, a power of 100 W and a flow of 16.5 L/min. The emission bands were measured in the wavelength range of 200 nm to 900 nm. The principal species observed were O 2 + ( A 2 Π u → X 2 Π g ), CO + ( A 2 Π → X 2 Σ), N 2 + ( B 2 Σ u + → X 2 Σ g + ), CO 2 + ( A 2 Π → X 2 Π), N 2 ( C 3 Π u → B 3 Π g ), O 2 ( b 1 Σ g + → X 3 Σ g − ), and CO ( a ' 3 Σ → a 3 Π). The behavior of the band intensities as a function of the N 2 percentage is consistent with recent Monte Carlo simulations. The electron temperature and ion density were determined by a double Langmuir probe. The electron temperature was found in the range of 1.55 eV to 2.93 eV, and the electron concentration in the order of 10 10 cm −3 . The electron temperature and ion density at pure N 2 and pure CO 2 agree with previous measurements.