Spectroscopy Diagnosis Of Argon Dielectric Barrier Discharge Plasmas

Ar dielectric barrier discharge plasma at low pressure was diagnosed by the optical emission (OES) and tunable diode-laser absorption spectroscopy (TDLAS) technology in this article. The variation trend of electron temperature with voltage, pressure, gas flow and N2 concentration was studied by OES technology. At the same time, a simple OES method called branching fraction (BF) was introduced to measure the density of Ar metastable state and compared to TDLAS in latter chapter. Furthermore, the density of Ar metastable state and gas temperature in DBD Ar plasma were measured using the tunable diode-laser absorption spectroscopy technology, and we also investigated their dependences on voltage, pressure, gas flow, electrode distance and N2 concentration. Following conclusions we got:1) Based on Fermi-dirac model (F-M) and Corona model, we calculated the electron temperature and studied its trend with changing discharge conditions. Electron temperature increased with the increasing voltage and N2 concentration, but when the pressure and gas flow were increasing, it decreased. Both the variation trends of the two models were consistent, while the value calculated by F-M model was always bigger than that by Corona model at the same experiment condition.2) The variation trends of densities of Ar metastable state 1s5, 1s3 calculated in OES-BF and TDLAS were similar, the value of 1s5 density both in the two methods was approximate, but the value of 1s3 density in OES was just about half of that in TDLAS technology.3) The density of Ar metastable state 1s5,1s3 and gas temperature were diagnosed by TDLAS. It was found that, when the voltage and gas flow increasing, both temperature and densities of 1s5,1s3 shown the similar trends, which increasing rapidly at first and then slowly. In addition, the variation with gas flow was smaller than that with gas flow. With pressure increasing, temperature and densities of 1s5, 1s3 increased till to a max value and then decreased. To increase the electrode distance properly, the density of 1s5,1s3 decreased while the gas temperature increased. N2 added to Ar presented a great negative effect on density of Ar metastable state. Even 0.5% N2 added to Ar, the densities of 1s5 and 1s3 decreased rapidly about to 50%, but then more N2 added, there was no obvious decrease about density.