The characterization of cathodic plasma electrolysis of tungsten by means of optical emission spectroscopy techniques

Abstract

Cathodic plasma electrolysis (CPE) of tungsten is investigated by means of optical emission spectroscopy in order to measure the electron temperature Te and the electron number density Ne from CPE micro-arc discharges. The relative intensity of W I lines recorded from seven spectral ranges are used in conjunction with the Boltzmann plot (BP) technique to measure Te ≈ 10000 K. For Ne diagnostics, the complex line shape of the Hα and the Hβ lines are analyzed in the frame of the spectral line broadening theory. The results showed two Ne values, (7 ± 3) × 1014 cm-3 and (7 ± 3) × 1015 cm-3, corresponding to different regions of CPE micro-arc discharges. The self-absorption effect on both studied H I lines was revealed and discussed as well. The SEM and XRD analysis showed a weak formation of rough oxide coating (WO3, W3O8) featured by the number of grains, channels, and holes.