Plasma parameters in the vicinity of the quartz window of a low pressure surface wave discharge produced in O2

Plasma parameters in the vicinity of the dielectric window of a low density, microwave discharge produced in O2 at 915 MHz are investigated by a spherical probe and optical emission spectroscopy while the microwave field distribution is measured by a spectrum analyzer. The electron energy distribution function is found to be strongly dependent on the position with respect to the slot antenna, exhibiting a group of energetic electrons at locations where the electric field and the optical intensity exhibit maximum values. The density of energetic electrons decreases sharply just a few cm away from the dielectric.