Article · Plasma Research Express · March 1, 2019

H 2 dissociation in Ar–H 2 arc discharge of moderate pressure

Abstract

Abstract The line intensity ratio technique for estimation of hydrogen-to-argon density ratio and hydrogen molecule dissociation degree in arc discharge in Ar–H 2 mixtures at moderate pressures (2–3 Torr) is analyzed. Intensity ratios of three hydrogen lines of Balmer series (H α (656.3 nm), H β (486.3 nm) and H γ (434.0 nm)) to ArI 750.4 nm (2 p 1 → 1 s 2 ) and ArI 811.5 nm (2 p 9 → 1 s 5 ) lines were examined. Effect of Ar fraction in Ar–H 2 mixtures on the diagnostic technique and molecular hydrogen dissociation degree in the large-volume high-density moderate-pressure Ar–H 2 arc was studied. Using ArI 811 nm line for the intensity ratio diagnostics in the arc discharge is not valid due to great role of the excitation from 1s 5 in production of Ar 2p 9 level. It is shown that to obtain the correct H density value it is necessary to account quenching of H* excited states by Ar atoms and H 2 molecules. Pair of H α and ArI 750 nm lines is the best choice for determining atomic hydrogen density using HI-to-ArI line intensity ratio technique because of the upper excited state of H α ( n = 3) is less subjected to quenching by Ar atoms and H 2 molecules as compared with higher H* levels ( n = 4, 5). It is shown increasing Ar fraction in Ar–H 2 mixtures results in growth of the molecular hydrogen dissociation degree.

Vacuum and Plasma ArcsLow-Pressure Plasma Processing and DiagnosticsAtomic and Molecular Physicshydrogen molecule dissociationatomic hydrogen densityplasma diagnostics

H 2 dissociation in Ar–H 2 arc discharge of moderate pressure

Abstract

More by Svetlana Avtaeva