Determination of vibrational and rotational temperatures in highly constricted nitrogen plasmas by fitting the second positive system of N2 molecules

Highly constricted plasmas are an active research area because of their ability to generate high activity of plasma beams, which exhibit potential in applications of material processing and film deposition. In this study, optical emission spectroscopy was used to study the highly constricted nitrogen plasma created at low pressure. The vibrational and rotational temperatures of molecules were determined by fitting the second positive system of nitrogen molecule. Under the conditions of the power densities as high as 7 similar to 85 W/cm(3) and the pressures of 2 similar to 200 Pa, the determined rotational temperature was found to be relatively low, increasing from 350 to 700 K and the vibrational temperature keeping at similar to 5000 K. The analysis of dissipated power revealed that similar to 80 % of input power is dissipated for the nitrogen molecule dissociation and the creation/loss of ions at the tube wall, producing an as high as 10(12)similar to 10(13) cm(-3) plasma with the nitrogen dissociation degrees of 2%similar to 15%. With the increase in the discharge pressure, more input power was found to be dissipated in the dissociation of nitrogen molecules instead of creation of ions, resulting in a higher density of radicals. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.