Plasmas Afterglows in N_2-O_2 Discharges

Abstract

The \(\mathrm{N}\) and O-atoms density versus the \(\mathrm{O}_{2}\) percent from 1 to \(4 \%$ into \(\mathrm{N}_{2}\) in \(\mathrm{HF}) flowing afterglow (at 7 Torr \(, 0.5 \mathrm{slpm}, 150 \mathrm{~W}\) ) was strongly decreasing for \(\mathrm{N}\) atoms from 15 to \(210^{14} \mathrm{~cm}^{-3}\) and kept a nearly constant value for \(O\)-atoms density : 7-9 10 \(14 \mathrm{~cm}^{-3}\), a value which is higher than the N-atom density in the range \(2-10 \% \mathrm{O}_{2}\) into \(\mathrm{N}_{2}\).

In RF afterglows, it was studied the effect of O-atoms and \(\mathrm{O}_{2}\) molecules when \(\mathrm{O}_{2}\) was introduced into \(\mathrm{N}_{2}\) before or after the plasma ( 8 Torr, \)1 \mathrm{slpm}, 100 \mathrm{~W}\) ). It is concluded to a quenching of \(\mathrm{N}_{2}\) active species by O-atoms more effective than with \(\mathrm{O}_{2}\) in the early and late afterglows.

At \(\mathrm{N}_{2}\) atmospheric gas pressure of DBD and Corona plasmas with \(\mathrm{O}_{2}\) impurity, it has been measured a density of the \(\mathrm{N}_{2} \mathrm{O}_{\mathrm{s}}^{1}\) excimer equal to about $10^{12} \mathrm{~cm}^{-3}\), largely less than the \(\mathrm{N}\) and \(\mathrm{N}_{2}(\mathrm{~A})\) densities : (5-7) \(10^{14} \mathrm{~cm}^{-3}\).