Emission spectroscopy of a surface wave sustained N-2-H-2 discharge

An experimental investigation on the degree of molecular dissociation in a surface wave-driven discharge (¿/2p=2.45 GHz) operating in N2–H2 mixture at pressure p=(66.5–266 Pa) is performed by means of optical emission spectroscopy. The dissociation degree of nitrogen molecules [N(4S)]/[N2] increases with the amount of hydrogen (up to 50%) in the mixture in correlation with the increase in electron temperature, when the electron density and the pressure are kept nearly constant. The relative number of hydrogen atoms keeps approximately constant with increasing H2 percentage (between 10% and 50%) in the mixture. The degree of molecular dissociation decreases along the plasma column length following the decrease in the electron density.