Liquid phase formation on graphite electrode surface in arc discharge

The graphite electrode surface is studied after impact by an electric arc burning in an argon atmosphere at a pressure of $50$ kPa. The arc occurred as a result of the local destruction of a graphite rod heated by electric current and preliminarily kept for $2 \times 10^3$ s at a temperature of about $3$ kK. After the arc discharge with a current of about $100$ A with a duration within $1$ s, we found drop-like particles, $0.1$–$0.3$ mm in size, on the graphite electrode surface, which is evidence of the local occurrence of liquid carbon phase at a temperature of about $3.3$ kK. With longer arc burning, the melting zone propagated over the entire working surface of the electrodes; the surface became smoothed.