Tuning Effect on the Electron Energy Distribution Function of an Inert Gas Mixture in Nitrogen Inductively Coupled Plasma Discharges

By using a Langmuir probe, the electron energy distribution function (EEDF) is measured in inductively coupled plasma discharges in N₂/Ar mixtures at 200 W rf powers. In pure N₂ discharges a Maxwellian EEDF is observed. When the mixing ratio of Ar increases, the distribution of high energy electrons evolves with a different trend from that of low energy electrons, resulting in an apparent “two temperature structure”of the EEDF. We discuss this non-Maxwellian EEDF and its effect on the measurement and the interpretation of “electron temperature” by both the probe and line ratio technique.