The study of micro-arc discharges during cathodic plasma electrolysis of refractory metals using the spectral line shape of Na i lines

Abstract

The micro-arc discharges during cathodic plasma electrolysis of refractory metals (Zr, Ti, Ta) are studied by means of optical emission spectroscopy. The fitting procedure based on three mutually shifted profiles is developed to analyze the complex line shape of Na I 568.64 nm and 615.86 nm doublets. Each profile includes effects of instrumental, Doppler, Stark, van der Waals and resonance broadening. The results show the existence of three discharge zones with electron number density values Ne1 = 7 × 1014 cm-3, Ne2 = (0.51) × 1016 cm-3 and Ne3 = (1.52.8) × 1016 cm-3 while those of sodium ground-state atoms are Ng1 = 1.4 × 1017 cm-3, Ng2 = 3.6 × 1017 cm-3 and Ng3 = (1.73.7) × 1018cm-3.