Theoretical insight into ArO2 surface-wave microwave discharges

Kinga Kutasi (1) , Vasco Guerra (2) , Paulo Sá (2, 3)

1 Research Institute for Solid State Physics and Optics [Budapest]
2 Instituto de Plasmas e Fuso Nuclear
3 Departamento de Engenharia Fsica, Faculdade de Engenharia da

A zero-dimensional kinetic model has been developed to investigate the coupled electron and heavy-particle kinetics in Ar-O 2 surface-wave microwave discharges generated in long cylindrical tubes, such as those launched with a surfatron or a surfaguide. The model has been validated by comparing the calculated electron temperature and species densities with experimental data available in the literature for different discharge conditions. Systematic studies have been carried out for a surfacewave discharge generated with 2.45 GHz field frequency in a 1 cm diameter quartz tube in Ar-O 2 mixture at 0.5-3 Torr pressures, which are typical conditions found in different applications. The calculations have been performed for the critical electron density n e =3.74×10 11 cm −3. It has been found that the sustaining electric field decreases with Ar percentage in the mixture, while the electron kinetic temperature exhibits a minimum at about 80%Ar. The charged and neutral species densities have been calculated for different mixture compositions, from pure O 2 to pure Ar, and their creation and destruction processes have been identified. The O 2 dissociation degree increases with Ar addition into O 2 and dissociation degrees as high as 60% can be achieved. Furthermore, it has been demonstrated that the dissociation degree increases with the discharge tube radius, while decreases with the atomic surface recombination of O-atoms. The density of O − negative ions is very high in the plasma, the electronegativity of the discharge can be higher than 1, depending on the discharge conditions.

Mots clés: Physical Sciences

Kinga Kutasi, Vasco Guerra, Paulo Sá. Theoretical insight into ArO2 surface-wave microwave discharges. Journal of Physics D: Applied Physics, 2010, 43 (17), pp.175201. ⟨10.1088/0022-3727/43/17/175201⟩. ⟨hal-00569587⟩