Power balance at a copper electrode submitted to a non-stationary electric arc in air. Measurement of the amount of liquid metal created and modeling of the heating

Abstract

In this paper, a measurement of the total amount of liquid metal created by an electric arc in air is made for copper anodes and cathodes. This amount is compared with usual erosion for the same experimental conditions for various values of the electrode gap (3–10 mm). It appears that the amount of liquid is ten times greater than the erosion for copper cathodes and may be fifty times greater for copper anodes. A method using experimental results and a numerical simulation of the thermal phenomena occurring in the electrode during the arc heating is then used to assess the characteristics of the power flux brought by the electric arc to the copper electrodes. It was found that about 80% of the energy received by the electrodes was conducted in the solid phase and that about 20% of this energy was used to melt or vaporize the electrode material. The power surface density brought to the electrodes was found in the range 4.6 × 10 8 –1.9 × 10 9 W/m 2 for the cathode and in the range 6.4 × 10 8 –1.1 × 10 10 W/m 2 for the anode.