Determination of the real experimental composition of the Ar-CO₂ mixture from calculation of the atomic excitation temperature

Laboratoire Arc Électrique et Plasmas Thermique (UPES A 6069 CNRS), Bâtiment Physique 6, 24 avenue des Landais, 63177 Aubière Cedex, France

Corresponding author: spectro@laept.univ-bpclermont.fr

Received: 17 December 1997
Revised: 30 March 1998
Accepted: 20 April 1998
Published online: 15 July 1998

Abstract

The temperature profiles in wall-stabilized atmospheric pressure arcs in argon and Ar-CO₂ mixture have been obtained at currents of 5 A to 40 A using spectroscopy techniques. The temperature profiles were measured using the absolute intensity of spectral lines. The monatomic excitation temperatures are determined experimentally from three chosen spectral lines of argon (415.86, 427.22, 696.54 nm), spectral lines of carbon (538.03, 477.175 nm) and spectral lines of triple oxygen (777.19, 777.42, 777.54 nm) in wall-stabilized arc. The results show the plasma had not the same composition locally as the gas injected in to the middle of the arc column. The results obtained are in good agreement with previously published data for pure argon and show the gradient formation of an arc core and the increase in axis temperature as the gas mixture is varied from pure argon to Ar-CO₂ mixture. Another result of these investigations is to show the importance of high purity gas when using monatomic gases, the addition of even a few per cent of CO₂ to argon having a drastic effect both upon extinction of the arc according to current values and upon the temperature profiles.