Laser induced stabilisation of the welding arc

Abstract

This paper deals with the influence of laser radiation on the stability of the welding arc. Experiments were conducted using a low power (500 W) Nd:YAG laser in combination with a gas tungsten welding arc. The laser induced arc stabilising effect was measured under various experimental conditions. It was found that the stabilising effect can be explained in terms of two phenomena: the absorption of laser energy by the arc plasma and the change of the arc plasma composition caused by strong evaporation of workpiece material. Both phenomena lead to a reduction of the effective ionisation potential of the plasma and thus provide a more conductive, stable plasma channel for arc root and column that overcomes disturbance by external forces. The proposed stabilisation mechanism was validated by measuring the absorption of laser energy by the arc plasma using a laser energy meter and the changes of arc plasma composition caused by the laser radiation by means of emission spectroscopy. © 2005 Institute of Materials, Minerals and Mining.