THE STUDY OF THERMAL-PROCESSES IN AN ELECTRODE SUBMITTED TO AN ELECTRIC-ARC

This article investigates the thermal phenomena that are occurring in an electrode submitted to an electric arc in air at atmospheric pressu re. Our purpose is to get a better understanding of the electrode eros ion phenomena concerning vaporization or liquid droplets ejection. For that we propose an original experimental device allowing the measurem ent of the liquid and vapor quantities created under the arc root. The principle of this device is based on the ejection of the liquid metal through centrifugal movement of the electrodes during the arc. Some r esults are given relatively to Ag, Cu and AgSnO2 Cathodes and anodes. Then we present a numerical modelling of the thermal phenomena induced in the electrode by the heat transferred from the arc root. We propos e a method to solve the difficulties related to this kind of << free b oundary >> problems induced by the fact that the electrode material ma y undergo various phase changes. Finally we show how to use this numer ical computation and the experimental results in order to estimate the power density input at a copper anode.