Comparative determination of the electron temperature in Ar- and N2-plasmas with electrostatic probes, optical emission spectroscopy OES and energy dispersive mass spectrometry EDMS

Abstract

The electron temperature T e as the often most essential parameter for applications of low pressures plasma has been derived from comparative in situ measurements with a single and a double electrostatic probe, and with optical emission spectroscopy OES and energy dispersive mass spectrometry EDMS as remote techniques. Electrodeless rf discharges maintained by electron cyclotron wave resonance ECWR in pure Ar and N 2 in the pressure regime from 10 −2 to 1 Pa have been used as sample plasmas. The evaluation of the OES- and EDMS-signals is described in detail. The pressure dependence of the T e -results derived therefrom is found to compare well with the data from the probe measurements, and with calculations from a charge carrier balance equation. By matching the OES data to the absolute T e -values from the probe measurements, numerical expressions have been obtained by which T e can be quantitatively calculated from the intensity ratios between selected emission lines from the Ar- and the N 2 -plasma. Furthermore, the EDMS-results are also shown to deliver quantitative information about T e .