Langmuir Probe and Optical Emission Spectroscopy Studies of Low-Pressure Gas Mixture of CO2 and N2

Optical emission spectroscopy was used to study a gas mixture glow discharge of CO2 and N2 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 O2+ (A2Πu → X2Πg), CO+ (A2Π → X2Σ), N2+ (B2Σu+ → X2Σg+), CO2+ (A2Π → X2Π), N2(C3Πu → B3Πg), O2(b1Σg+ → X3Σg−), and CO (a'3Σ → a3Π). The behavior of the band intensities as a function of the N2 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 1010 cm−3. The electron temperature and ion density at pure N2 and pure CO2 agree with previous measurements.