Large-scale Ar and N2-Ar microwave plasma sources

The spatial structure, including a discharge and a remote plasma zone, of a large-scale, slot antenna excited microwave plasma source operating in Ar and N-2-Ar mixtures at 2.45 GHz has been investigated. The discharge source is sustained by the electric field of pure TM surface modes. Optical emission spectroscopy, probe diagnostic techniques and radiophysics methods are applied to measure the emission intensity of radiative states, the electron density and the microwave field intensity, respectively. The spatial distribution of the electron density and the intensity of emission lines belonging to the 2nd positive and 1st negative systems of N-2 follow the electric field pattern in the active-discharge zone of the plasma source. On the contrary, the populations in vibrational and rotational levels of the N-2(C-3 Pi(u)) state are homogeneous irrespective of the azimuthal position.