AVS 56th International Symposium & Exhibition | |
Plasma Science and Technology | Tuesday Sessions |
Session PS2-TuM |
Session: | Atmospheric Plasma Processing and Microplasmas |
Presenter: | S.G. Belostotskiy, University of Houston |
Authors: | S.G. Belostotskiy, University of Houston T. Ouk, University of Houston V.M. Donnelly, University of Houston D.J. Economou, University of Houston N. Sadeghi, Université Joseph Fourier de Grenoble, France |
Correspondent: | Click to Email |
Optical Emission Spectroscopy was employed to study a high pressure (100s of Torr) DC microdischarge in argon, with traces of N2 and H2 present and acting as optical tracers. Spatially resolved measurements of gas temperature across the 600 μm slot-type discharge were obtained from analysis of the rotational structure of two transitions of the first positive band of N2: B3Πg(v=4) → A3Σu+(v=1) and B3Πg(v=5) → A3Σu+(v=2). Gas temperature profiles peaked at the cathode side of the discharge and slowly decreased towards the anode. Such behavior is consistent with the physics of DC discharges, where most of the power dissipation occurs in the cathode layer. The gas temperature increased with increasing current, reaching a maximum of Tg = 1200 K at I = 30 mA and P = 600 Torr. Electron densities were extracted from the spectral profile of the Hβ line. The profile was fit with a Voigt function, which included Doppler, pressure, instrumental and Stark broadening. The electron density was estimated from the contribution of Stark broadening. The spatial profile of electron density was found to have a maximum in the cathode sheath edge region, followed by a minimum in the bulk plasma, and then a maximum some distance from the anode. This spatial distribution was explained by the non-homogeneous structure of the microdischarge, having a highly contracted positive column. The electron density near the sheath edge increased with both pressure and current reaching ne = 1.7∙1014 cm-3 at I = 30 mA and P = 600 Torr.