HE-N2 RADIOFREQUENCY DISCHARGE - INFLUENCE OF N2 ON DISCHARGE AND AFTERGLOW

A diagnostic study of energy transfer processes in a He-N2 flowing discharge and afterglow has been performed in a radiofrequency-produced plasma cooled in a liquid nitrogen bath. Optical emission spectroscopy in the visible and infrared spectral range as well as Langmuir probe diagnostics were used. The vibrational kinetics of CO injected in such an afterglow has been examined. It shows a slow cooling of the electrons in the afterglow regime. The electron kinetics responsible for CO vibrational excitation is turned off when N2 is added to the He discharge, while that for vibrationally excited N2 molecules is turned on. The results are discussed on the basis of previous theoretical calculations and experiments on the He-N2 system.