Eur. Phys. J. D 41, 143-150 (2007)
https://doi.org/10.1140/epjd/e2006-00187-x

Excessive Doppler broadening of the H_α line in a hollow cathode glow discharge

Radial distribution, influence of surface coverage and temperature effect

¹ Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade, Serbia
² Military Academy, Pavla Jurišića – Šturma 33, 11105 Belgrade, Serbia

Corresponding author: ^a nikruz@ff.bg.ac.yu

Received: 27 April 2006
Revised: 4 July 2006
Published online: 18 August 2006

Abstract

A comparative study of the radial intensity distribution of the excessively Doppler broadened hydrogen H_α line in a hollow cathode (HC) glow discharge operated in hydrogen and argon-hydrogen gas mixtures with stainless steel (SS) and titanium (Ti) cathode is reported. The main interest of this work is focused on the dependence of radial distribution upon cathode material and cathode surface composition. The analysis of experimental radial distributions and results obtained from H⁺↦ metal surface interaction simulation combined with available data for H ↦ metal target interaction explains the difference between SS and Ti cathodes. These results explain also the important role of metal hydrides at the cathode surface for discharge-HC interaction. The influence of the hollow cathode temperature on the radial distribution of the excessively broadened H_α line and on the emission of Ar I and Ar II lines from discharge in argon-hydrogen gas mixture are also investigated. The increase of the excessive Doppler broadened part of the H_α line profile with HC temperature is always detected. The intensity of Ar I and Ar II lines is also used to examine the influence of small admixtures of hydrogen in argon.