Diagnosis of the DC Glow Discharge Plasma Generated Inside a Metallic Tube by Optical Emission Spectroscopy
YIN Li-yong,WEN Xiao-qiong*,WANG De-zhen
State Key Laboratory for Materials Modification by Laser, Ion, Electron Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China
Abstract：Optical emission spectroscopy method was used to diagnose the normal dc glow discharge plasma generated inside a metallic tube. The active species in the plasma were identified. The electron excitation temperature in the plasma was determined by the Boltzmann plot method. The vibrational temperature of N2 molecules in the plasma was determined by analyzing the emission spectrum lines of the N2 second positive system (C3Πu→B3Πg).The dependence of the electron excitation temperature and molecular vibrational temperature on the pressure was investigated. The experiment results show that in the Ar60%+N240% glow discharge plasma at 20 Pa, the active species are the Ar atoms, Ar ions, second positive series of N2 transitions and the first negative series of B2Π2u→X2Σ+g transitons; the electron excitation temperature is (15 270±250) K, and the vibrational temperature of N2 molecules is (3 290±100) K. The electron excitation temperature and molecular vibrational temperature decrease with increasing pressure. These results would give some valuable guide to the study on inner surface modification of metallic tubes.
Key words：Metallic tube;Direct current glow discharge;Optical emission spectroscopy;Electron excitation temperature;Molecular vibrational temperature
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