Optical emission spectroscopy study of a medium pressure Nitrogen flowing afterglow from a $\sim $1kW microwave excited plasma source

Nitrogen flowing afterglows in the medium pressure range (1-10torr) are of topical interest for applications in semiconductor film growth and biological decontamination. The spatio-temporal decay characteristics of a 2.54GHz microwave excited flowing N$_{2}$ plasma have been investigated, after a T-junction was introduced in the plasma path to optically isolate the plasma source and afterglow. The results from optical emission spectroscopy studies ($\lambda $=200-1000nm), including gas temperature estimates deduced from high resolution spectra, are compared with a simple kinetic model for key atomic and molecular nitrogen species, and are correlated to gas pressure, and gas flow rates.