Two Approaches in Determination of Copper Vapours Content in Thermal Plasma by Optical Diagnostics

This work presents a comparative study of two diagnostic approaches for determining copper vapour admixtures in the thermal plasma of an electric arc discharge. The emission of plasma of arc discharge between copper electrodes was analysed using optical emission spectroscopy (OES) under discharge currents of 3.5 and 30 A. Two sets of plasma parameters were used as inputs for equilibrium composition calculations: (1) radial distributions of excitation temperature and copper atom number density, and (2) radial distributions of excitation temperature and electron density. The excitation temperature was determined using the Boltzmann plot technique, while electron density was obtained from spectral line broadening using Fabry-Pérot interferometer and by applying the Saha equation. The consistency of the calculated plasma compositions using both input sets demonstrates the applicability of indirect diagnostic methods for evaluating the erosion resistance of electrode materials.