Diagnosis of the electron temperature in dielectric barrier discharge by optical emission spectroscopy

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Glow dielectric barrier discharge appears as an attractive solution to realize near atmospheric pressure cold plasma process suitable for all the surface treatments including thin film coating and material making. Such development requires a large understanding of the dielectric barrier discharge (DBD) physical and chemical process. The objective of this work is to contribute to that understanding. In this paper, we report the results of the measurement of the spectrum from 690nm to 800nm in DBD in argon. The electron temperature T_e has been estimated using intensity ratio method by optical emission spectroscopy under difference experimental conditions. According to Local Thermodynamic Equilibrium (LTE) theory, the electron temperature T_e can be assumed equal (equals) to the excitation temperature T_exc, namely T_e=T_exc=T. Therefore, the plasma temperature T can be determined by comparing the relative intensities of spectral lines from the same element and ionization stage. The spectral lines 763.72nm (2P₆→1S₅) and 772.63nm (2P₂→1S₃) of Ar atom are chosen to estimate the electron excitated temperature. The experimental results show that the electron excitated temperature is in the range of 0.3-8eV in Ar under different pressures. The results also show that the electron excitated temperature increases with the decreasing of the applied voltage. The results provide a reference for the controlling of DBD and are of great importance to the industrial applications.