Langmuir probe and optical emission spectroscopy studies of low-pressure gas mixture of O_2 and N_2

摘要

Optical emission spectroscopy was applied for plasma characterization of a gas mixture glow discharge of O_2 and N_2 at a total pressure of 0.5 Torr, power of 10 W and with 40 l/min flow rate of gases. The main diagnostic techniques applied to determine plasma parameters were the optical and probe diagnostics. The emission bands and lines were measured using a spectrometer in the wavelength range of 200 to 1000 nm. The principal transitions observed were O_2(B~3∑_u~- -X~3∑_g~-); O_2(b~1∑_g~+-X~3∑_g~-); O_2~+(A~2∏_u -X~2∏_g); O_2~+(b~4∑_g~- a~4∏_u); O; N_2(C~3∏_u-B~3∏_g); N_2~+ (B~2∑_u~+- X~2∑_g~+) and N_2(B~3∏_g-A~3∑_u~+). The electron temperature and ion density were determined by a double Langmuir probe. The electron temperature was found in the range of 1.13 eV to 1.40 eV, and the electron concentration in the order of 10~(10) cm~(-3).