Measurement of ion temperature in N2/Ar and O2/Ar ECR plasma

Abstract

Ion temperatures in N2/Ar and O2/Ar electron cyclotron resonance (ECR) plasmas have been measured with high-resolution optical emission spectroscopy. It was found that the Ar ion temperature in N2/Ar plasma decreased drastically as the nitrogen gas concentration was increased, while the electron temperature slightly increased. The uniformity of the radial electron density distribution also increased with increasing the nitrogen gas concentration. These results suggest that the radial electric field decreased with increasing the nitrogen gas concentration, and as a result, the transverse ion temperature in N2/Ar plasma decreased. On the other hand, the ion temperature in O2/Ar ECR plasma increased as the oxygen gas concentration was increased and the electron temperature considerably increased. This increase in the electron temperature may be caused by generation of negative ions. As the negative ion generation affects the electron density and hence the electron temperature, the ion temperature in O2/Ar plasma is increased with increasing the oxygen gas concentration.