Determination of electron temperature in ion plating discharges by optical emission spectroscopy

By the use of Optical Emission Spectroscopy (OES), the electron temperature, T_e, is estimated for argon based dc diode and thermionic triode discharge plasmas. In addition, the dependence of T_e on the presence of electron beam evaporated titanium in the plasma is investigated. The difficulties associated with calibration when determining T_e by OES are highlighted; the uncertainties influence calculated T_e values in relative and absolute terms. Nevertheless, our results indicate that (i) T_e may rise when discharge enhancement by thermionic emission is utilised, and (ii) T_e could be increased significantly by metal evaporation. The implications of these findings are discussed.